One-Family Houses With and Without Basements, on Sites Without Bedrock

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NATIONAL RESEARCH COUNCIL OF CANADA Technical Translation TT-648

Title : One-family houses with and' without basements, on sites without bedrock.

( s d h u s med og uten kjeller

pP

jordtomt).

Author: Sven Erik Lundby.

Reference: Norges Byggf ors'm~ingsins titut t

,

Rapport Nr. 11, 1954.

3 3 ~ .

Translator: H.A,G, Nathan, Translations Section, N. R.C,

Library.

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Foreword

It is with great pleasure that the Division of

Building Research sponsors the translation of this re-

port as a contribution to Canadian housing studies,

The Norwegian Building Research Institute is well known

and highly regarded by the Division of Building Research

and personal contacts have been established through

a

number of visits by menibers of both staffs, Tliere is a

remarkable similarity in the building problems facing

both countries and therefore much to be gained by ex-

changes of information in which translations such as this

play a vital part,

Ottawa

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ONE-FAMILY HOUSES WITH

-4ND

WITHOUT BASEIIENTS, ON SITES

WITHOUT BEDROCK

Preface

For sorne time the Norwegian Building Research Institute

has shown a growing interest in houses without basements.

The

Norwegian Housing Directorate is also interested to know how the

different methods of construction compare with each other from the

economic point of view, Therefore, these two bodies decided to co-

operate in obtaining some idea of the costs involved,

Jointly with the Housing Directorate the Norwegian

Building Research Institute drew up the p r o g r m e for an investi-

gation and suggested the types of houses, foundation methods, etc.,

to be studied, The architects of the Housing Directorate designed

the houses suitable for the investigation and prepared complete

drawings and descriptions. Subsequently, estimates of the material

required and cost calculations were made by the Housing Directorate

and the expenses were borne jointly by the two agencies.

The work was carried out under the direction of

Mr, ~drgensen,

the chief clerk of the Housing Directorate, The

drawings were made by

M r ,

Christiansen, architect, while the exten-

slve calculation work was carried out by Mr, Vasdal (cost account-

ant) and Messrs. Lyn@;raff and Karlsen (secretaries).

The cost of

plumbing and electric wiring was calculated by

Nlr.

flstbd (engineer)

and

the firm of Klaus Lefdal

&

Co,

A/S,

while the paint work was

estimated by Mr. Thorstensen (painter).

The drav~ings

for and descriptions of

l;he

electric heating

system for the floors of the house types with soil-supported con-

crete slabs, without peripheral footings, were made by civil engin-.

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Therefore, inuch of the material for the conrparison was procured from sources other than the Norwegian Building Research Institute-although the material was eventually dealt with by this institute.

By taking charge of the extensive work of drawing and calculating the Housing Directorate was able to carry out the investigation, and the Norwegian Building Research Institute is in- debted to it for this cooperation,

Bacbround of the Inves tiaation

The Norwegian Building Research Institute nas not merely interested in obtaining an insight into the costs of various types of houses without basements built under Norwegian conditions,

Along ?vith such a general survey, it was thought necessary to carry out a more detailed economic comparison between special

forms for the foundations, Indeed the technical problems encoat- ered in some of the present foundation methods are so considerable that the Norwegian Building Research Institute cannot allot a

great deal of expenditure without first making some sort of estimate of the costs involved.

It appeared that only a few such cost analyses were available. Quite a number of economic comparisons are being made by various contractoras while worlcing on special projects, but such

analyses are not being publisl~ed. The litersture on more systematic comparisons is meagre.

A

group of representatives from the

Nor-gr'egian building industry who visited the

U.

S.A. in

1951,

made individual rough comparisons between houses with and without basements during the preliminary work for their report(2). The cost of building was analyzed for a house without basement with soil-

supported and artificially heated floor, At the same time the house had foundation walls extending down to the unfrozen ground. It was found that in this case the floor space of a basmentless house could not be increased by more than

15

or 2C$ over that of a house with a basement without increasing the cost of construction,

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Along with a discussion "basements versus no basements", the periodical "Hem i Sverigett made cost calculations on a

relatively large scale(4),, One-family houses with l$-storey and one-storey and with rooms in the basement were compared with

similar dwellings in which the rooms in the basement had been re- placed by utility rooms built on the first floor of the house,

The houses in question had been built on sites without bedrock* The investigation showed that as far as the cost of these basementless houses was concerned they could scarcely compete with the

conventional types with basements, This question is also dealt with in a report by the Housing and Home Finance Agency in the

U.

S. A.

( 3 ) .

However, the available material was not extensive enough to give a sufficiently detailed picture of the conditions from the Norwegian point of view.

Method Employed for the Investi~ation

The investigation was based on six different types of house design, As far as possible these designs should be similar in floor area and floor-area distribution between the individual rooms.

At the same time with these six basic designs six different foundation methods were eniployed on level, horizontal sites without bedrock.

Both the various designs and the foundation methods are discussed in greater detail, The costs of the 30 types of houses shown in Fig, 1 were studied for all possible combinations, In the different combinations shown construction costs may be compared from house to house first with respect to design and then with

respect to foundation method- In order to render the material as valuable as possible to the building trade, the costs of the

different types of work for each individual design have been speci- f ied,

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scription. estimates results, f o~mation

These conditions are evident from the drawings and de- The costs are bound by time and location,

If

other are useC z.s the basis, this will of course affect the The material must be appraised from the very detailed submitted,,

in-

The prices may be compared from house to house, There- fore, they should give a fairly correct picture of the economic relationship between the individual designs, On the other hand, the zbsolute size of a house cannot be used as an accurate me:lsure of what such construction work will cost,

It is obvious that it pays to avoid unnecessary blasting of rock in order to build basements, Foundztions on bedrock were not taken into account in this comparison, but the figures are such

that those interested in b~sements built on bedrock may dram certain conclusions, The Norwegian Building Research Institute plans to shed some light on these conditions as well,

The comparison is based on six designs, three for one- storey houses and three for 13-storey ones, Each of these groups includes a house without basement, one with partial basement for foot storage space only and one with all the utility rooms in the basement, including laundry, dead-storage space and fuel storage,

The main design groups are as follows:

A,

One-storey house without basement (Fig,

4).

B, One-storey house with only a food-storage room in the basement (~ig.

5).

C, One-storey house with all the utility roorns in the basement (I?ig.

6).

D,

1;-storey house without basement (Fig, 7 ) .

E, l$--storey house wit11 only a food-storage room in the basement ( ~ i g , 8).

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F,

13-storey house v i t h a l l t h e u t i l i t y rooms i n t h e basement ( ~ i g . 9 ) .

G r e a t e s t p o s s i b l e s i m i l a r i t y of the v a r i o u s d e s i g n s i n f l o o r a r e a and f a c i l i t i e s was t h e main requirernent. The f a c t t h a t a one-storey house having t h e same l i v i n g space, room d i s t r i b u t i o n and f l o o r a r e a a s a 1;-storey house may b e taken c a r e of more

e a s i l y , and perhaps more conveniently, 'oy t h e housewife was d i s - regarded h e r e , l e a v i n g t h e d e c i s i o n w i t h r e s p e c t t o t h i s t o t h e r e a d e r himself, Wherever t h e housss have t h e sane f l o o r a r e a t h e f a c t t h a t some d e s i g n t y p e s have s t a i r s and some do n o t must of

course a l s o b e taken i n t o account.

A s f a r a s t h e u t i l i t y rooms a r e concerned t h e food- s t o r a g e rooms i n t y p e s B and E have been designed s l i g h t l y more roomy than t h o s e of t h e o t h e r types s o l e l y f o r p r a c t i c a l reasons" The c o s t of b u i l d i n g basements c o n s i s t i n g merely of food-storage rooms would b e reduced b u t l i t t l e by c u t t i n g t h e i r f l o o r a r e a dovm

t o t h a t of o r d i n a r y food-storage roorns. I n o t h e r r e s p e c t s t h e

u t i l i t y rooms t a k e up p r a c t i c a l l y t h e same f l o o r a r e a r e g a r d l e s s of v h e t h e r they a r e l o c a t e d i n t h e a d d i t i o n o r i n t h e basernerlt,

h he

n e t measurements of t h e u t i l i t y rooms i n t h e baseslent a r e l a r g e r by approximately

0.6

sq.m. t h a n those i n t h e a d d i t i o n , b u t t o corn- p e n s a t e f o r t h i s , some space i s taken up by t h e basement s t a i r s . )

I t was important t h s t t h e v a r i L m t s should form a p l a i n building-block s e r i e s showing as c1e:;irly a s p o s s i b l e the elements making up t h e i n d i v i d u a l vt~zriants. This g r e a t l y f a c i l i t a t e d t h e

c a l c u l a t i o n work.

The l i v i n g space i s d i s t r i b u t e d over two a r e a s , The n u c l e u ~ i n a l l t h e d i f f e r e n t d e s i g n types c o n t a i n s t h e l i v i n g room ( 25.7 sq.m, )

,

k i t c h e n (10.9 sq.n:, )

,

bathroom, hallway and v e s t i b u l e . S i n c e t h e house c o n s i s t s of one o r 1$ s t o r e y s , t h e r e s t of t h e

l i v i n g space, i, e,

,

two bedrooms of

11.7

and

9.6

sq.m.

,

respectively, e l t h e r a d j o i n s t h e nucleus o r has been superimposed on i t ,

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The b;,sementless house types A and

D

have been designed w i t h an a d d i t i o n f o r t h e u t i l i t y roons n i t h a g r o s s f l o o r a r e s of

23.2 sq.m, This corresponds t o 29% o r t h e l i v l ~ - ~ g space :mu p r e s e n t s the l l r n i t of .;{hat i s r e a d i l y s a c r i f i c e d t o t h e u t i l i t y r o o m i n b a s e r n e i ~ t l e s s l ~ o u s e s ,

The u t i l i t y room3 a r e l a i d out i n t h e f o l l o ~ u i n s way, I n 7sa;;er:ientless housss A an6 D t h e food-storace room 11as been p l a c e d

ln. 3.n a d d i t i o n t o the _{g r o u ~ i < ~}_{f l o o r ,} I11 house thq~es -:jith p a r t i a l Sasenent, e.g. B and E, t h e foocri-storaze rooln has been ylnceS~ i n

t h e bssernent n i t h st3irs froin t h e hallway lez-ding t o i t and, a s ~.ie-r_i;ioned above, has s s l l ~ h t l g l a r g e r f l o o r area, F i n a l l y , I n

tjr_:es C and F a l l tLle u t i l i t y roorns a r e i n t h e basement ( c f , Fig..

2).

I n p r a c t i c e t h e laundry i s s t i l l most f r e q u e n t l y i n s t a l l e d i n t h e same p a ~ > t of t h e house a s t h e l i v i n g space owing t o t h e r e - q u i ~ e d i n s u l a t i o n . Tlie u t i l i t y rooms vhich m e 02 l i z h t construc- t i o n liiag t h e n b e plvced i n ,in a d d i t i o n t o tile !louse. Such a d i s t r i - b u t i o n i s cior3 economic il,

With rospec't t 3 the windo:;s the v ' i r l e t g of ~ Y ; J ~ S used i n s house i s g r e a t e r than usu:.l. Then t h e r e i s t h e e x i t t o t h e

garden, a shading w a l l f o r the s e a t s , e t c . However, u p o i n t has 3een nnde oi' d e s i g n i n s and ecjuippilllf a l l t h e houses : v i t l i t h e

gtc;reatcst p o s s i b l e ciii:i13rl tjr. Wherever i t lV/as necessary t o use d i i ' f e r e n t d e s i g n s and m a t e r i a l s they were s t a n d a r d -:/ithln t h e o r d l r ~ a r y , reasonable p r i c e c l 2 s s n e v e r t h e l e s s ,

I n t h e house t y p e s e n t i r e l y without baseraent ( t i ~ e s A

anu

D)

the u s e f u l n e s s oP food-storage roorns w i l l d i f f e r soniewhat ee2ending on whether thecr have vjooden f l o o r i n g a s i n founciation ~ret:lorls 1 t o

4

o r a r e soil-s'ii13i10rtsd a s i n methods

5

and

6,

There-

E

l o r e , i n t h e former tyye t h e food-storage rooriis have been lowered so t h a t t h e f l o o r s w i l l l l e 100 cm. below those of t h e 13tt5r, r e - sultin;. o r course i n a corres;anding i n c r e a s e i n c o s t ,

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The method of g a b l i n g t h e one s t o r e y houses d i f f e r s from t h a t of g a b l i n g t h e 1 3 - s t o r e y houses The r i d g e i s lengthwise i n t h e former and t r a n s v e r s e i n t h e l a t t e r .

The houses have been drawn on a 60-cm. p l a n , shol:ring t h e d e s i g n s a s c l e a r l y a s p o s s i b l e , a s can b e seen i n Fig.

4.

E'oundz t i o n 1,ic

tm

iiS Fig. 1 sho~:s, t h e c a l c u l a t i o n s 7ivere c a r r i e d o u t f o r

t h e following s i x f o u n d a t i o n metliods: 1; Columns (Fig, l l ) , 2- Discontinuous load-bearing w a l l s ( ~ i g . 1 2 )

3*

Shallow load-bearing ( ~ i g .

13),

4=

Corn-plete load-bearing w a l l s ( F i g ,

14)

5*

Soil-supported c o n c r e t e f l o o r s l a b ( F i g . 1 5 ) -

6.

Soil-supported c o n c r e t e f l o o r s l a b with f o o t i n g s ( F i g 1 6 ) *

The columns used i n I-pethod 1 a r e of c o n c r e t e and have a t h i c k n e s s of 25 cm, They extend t o t h e zround anci a r e enlarged a t t h e bottom. S t e e l p l a t e s a r e placed on t h e c o l u m s , The d i s c o n t i n u o u s load-bearing w a l l s (method 2) a r e b u i l t down t o

t h e unfrozen ground,

The corriplete load-bearing 7 ? ? a l l s (method

4 )

a r e 20 cm. c o n c r e t e w a l l s extending down t o t h e unfrozen ground,? The w a l l s around t h e basement a r e i n s u l a t e d from t h e i n s i d e by means of 7 crn. wood-fibre cement s l a b s (Fig. 1 7 ) The i n t e r i o r load-bearing w a l l h a s a t h i c k n e s s of

15

cm,

The shallow load-bearing w a l l s (method

3)

d i f f e r from t h e complete load-bearing w a l l s i n t h a t they extend only t o t h e s o l i d s o i l , I n o r d e r t o prevent f r e e z i n g , h e a t i n g c a b l e s a r e embedded i n the foundation,

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In the houses with soil-supported concrete floor slzbs (method

5)

the floor is heated electrically. Previous calculations have shown that this ty-pe of construction is too expensive when

the footing extends down to the unfrozen ground (method

6).

Con- crete slabs should have only reinforced edges or a creatly reduced depth of foundation. However, the design with peripheral footing has been included here for the sake of clarity,

As mentioned above, in ciesigll types with soil-supported floor the latter is heated either by electricity, hot air or hot water, or by radiators or stoves in the conventional manner. For

the present investigation electric heating for the floor T ~ ~ a s chosen because no furnace flue is required for this foundation method

But this does not mean that electric heating in the floor is

economically superior to other heating methods for the basementless house. This question does not lie within the scope of the present investigation.

It has been assumed that the chosen ty-pe of foundation v!ith concrete slabs down to the unfrozen ground, without footing,

is frost-resistant because of the heat supplied to the floor,

Drawings and Description

Detailed dra*bvings of' the different design types were made by the Norwegian Housing Directorate on a scale of

1:50.

At the

same tlme an accurate description of the different designs ?ras prepared of which only the following points are presented here Foundation Work

It has been assumed that the sites for all the design- ty-pe houses are level and horizontal llvithout bedrock, This item is included in the necessary rough levelling, In cases requiring no excavation, i, e,

,

baser:ler,tless houses, and houses that have complete load-bearing nalls and thus are not soil-supported, the top soil is rell:oved, leaving a space of

60

crlz below tlie floor

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j o i s t s . No s o i l fieed b e removed f o r houses t o b e b u i l t e i t h e r on columns o r on discontinuous load-bearing walls. For houses with basements the s o i l i s excavated t o a depth o f

30

cm. below t h e

f i n i s h e d f l o o r and t o n d i s t a n c e o f

50

cm. from t h e s i d e s of t h e e x t e r n a l f o u n d a t i o n 11:all. Trenches a r e excavated f o r a l l the con- d u i t s v i t h i n the b u i l d i r q and o u t s i d e t o a d i s t n n c e of r i v e metres from t h e house. A l l t h e manholes r e q u i r e d have been allowed f o r , h u t t h e p a t h up t o t h e house has not been included,

Only t h e uinount of s o i l r e q u i r e d t o e n l a r z e t h e h o l e s a t t h e bottom of t h e columns i s removed i n t h e manner d e s c r i b e d by Brochmaml and Mellbye ( l ) i n t h e i r r e p o r t on t h e one-f'ail~ilg house f o r t h e C h r i s t i a n i a Splgerverk p r o j e c t . P r o v i s i o n has been made f o r pouring t h e coluims h e r e a s well.

The h o l e s x e r e f i n i s h e d here x i t h a crovbar and t h e l o o s e s o i l was picked up with a p o s t h o l e spade used l i k e sugar

tongs. I n Norway, such sp2des a r e used 1,yhen t e l e g r a p h p o l e s a r e e r e c t e d , The fou;rl3atioli a t t h e bottom of t h e h o l e mas enlarged u s u a l l y i v i t h o u t e;:cnvatf n.g t h e h o l e zny f u r t h e r , The bo t tori1 p a r t of t h e column was p r o t e c t e d by p l a c i n g s t r o n g a s p h a l t e d r o o f i n g ho21.d d i r ~ e c t l y i n t o t h e h o l e >ni! f o r t h e upper. part a 1-me long

s t o v e p i p e ivas used a s t h e s l i u t t e r i r u , ,4bove g r o w d a. s i r r i l a r p i p e 1s joined l e n g t h v ~ i s e by two s t r e t e l l i n g screws.

The gener: 1 ~cea..n?:.~%r~ents of t h e foundations a r e eviclent from the summary of t h e f'cu1d~~l;ion methods, The use of ready-mixed c o n c r e t e has been included i n t h e e s t i m r ~ t e s . The aq:ork i s c a r r i e d out as s p e c i f i e d by 1J;rlt~egian Standard 428. Except f o r t h e

C O ~ U I ~ ~ S , $*I x

4"

~ C I S ~ S and A" s h u t t e r board is used f o r t h e con- c r e t e forms, I t i s a s s w e d t h a t t h e s t a y s w i l l be used a g z i n i n t.he framework. The f o u n d a t i o n vu.llalls a r e provided w i t h o b s e r v a t i o n h o l e s ,

When t h e concrete-slab f o u n d a t i o n s a r e 5 - c i l t t h e ~ r 0 ~ d i s f i l l e d up f i r s t with coarse g r a v e l and t h e n v?ith a l a y e r of

(13)

f i n e sand, A vspour b a r y i e p or" asyhalt s h e e t and c o n c r e t e s l c b

n i t h grouted g a l v a n i z e d p i p e s f o r t h e e l e c t r i c :vires i s then p l a c e d over t h i s . While c o n c r e t i n g , t h e s l a b s a r e trirrmed and f a c e d t ~ l i t h 40 x 40 cm. a s p h a l t t i l e s ,

I n t h e basement room, o r food-storage room i n t h e addition, t h e c o n c r e t e f l o o r i s f i n i s h e d with a l a y e r of f i n e r a z g r e g a t e i n a mi:iture r a t i o . of

1:4:

6

on a 20 cm. l a y e r of broken stone,

S i n c e an a d d i t i o n t o a house i s b u i l t above ground, t h e laundry always has a

5

cix, c o n c r e t e f l o o r f i n i s h e d n i t h a s t e e l smoothing t r o v ~ e l . The f l o o r of t h e dead-storage space has a top la.yer of f i n e r aggregate i n t h e houses w i t h s o i l - s u p p o r t e d c o n c r e t e f l o o r s . The bathrooms have c o n c r e t e f l o o r s i n a l l t h e houses. If

t h e f o u n d a t i o n s a r e b u i l t e i t h e r on colur~ms o r on load-bearinz v ~ a l l s a

5

cr-1. l a y e r of r e i n f o r c e d concrete i s poured on two p r o p e r l y over- lapping l a y e r s of a s p h a l t e d cardboard. The f l o o r s a r e f inislled n i t h a s t e e l smoothing trowel,

The e s t i m a t e d h e i g h t of' t h e shallow load-bearing w a l l s ( p i g . 13), which extend only down t o t h e s o l i d ground, i s 80 cm.

A l l the w a l l s surrounding the baseraent room a r e r o w h l y p l a s t e r e d , washed and g i v e n too o u t s i d e c o a t s of a s p h a l t emulsion.

The f o u n d a t i o n s f o r t h e s t a i r s a r e poured on broken s t o n e s d o \ ~ l i t o t h e unfrozen ground, t o t h e depth of t h e f o u n d a t i o n w a l l s i f

rrlethod

3

i s a p p l i e d (vhen t h e s o i l i s heated by a h e a t i n g c a b l e ) , If t h e f o u n d a t i o n c o n s i s t s of s o i l - s u p p o r t e d c o n c r e t e f l o o r s l a b s , t h e o u t s i d e s t e p s a r e poured a s detached b l o c k s on the ground.

A d r a i n a g e system comprising two rows of 23" d r a i n p i p e s l a i d i n t h e u s u a l way on t h e o u t s i d e along t h e w a l l s around t h e basement roorfi has been included i n t h e estimates.

(14)

The t r e n c h e s a r e f i l l e d up a g a i n and t h e d r a i n a g e d i t c h i s f i l l e d with s t o n e up t o 50 cml, belol-r t h e ground. The ground around t h e b u i l d i n g s i s ~ m d e t o s l o p e dotvnlvards from t h e w a l l s and a s u r f a c e d i t c h rnay p o s s i b l y be dw. I t has been assumed t h a t tile top s o i l v r i l l be p u t back on an a r e a intended f o r seeding.

Carpentry

Basement p a r t i t i o n w a l l s a r e of ivood and x

3''

with 5/8tt rough p a n e l l i n g on one s i d e .

A l l t h e b u i l d i n g s a r e modern frame houses. The t i e s a r e 2" x

4"

and t h e summers

4It

x

4".

The s t u d s a r e 2 t t x

4t1

and 60 cm.

a p a r t . The cornex- p o s t s a r e

4''

x

411.

I n c a s e of l a r g e window openings s t i f f e n i n g of t h e frarneworlr has been rdlowed f o r . The

s i l l under t h e mindoe i s 2" x

4"

and t h e angle b r a c e 1" x

5".

The frame w a l l s a r e b u i l t with 1$" x 3" timber framing.

The e x t e r n a l w a l l s a r e covered w i t h a l a y e r of d i f f u s i o n - proof f i b r e b o a r d and have

$"

p a n e l l i n g on t h e i n s i d e and v e r t i c a l

7J8" p a n e l l i n g with a l a y e r of impregnated f i b r e b o a r d on t h e out- s i d e , The e x t e r n a l w a l l s a r e i n s u l a t e d w i t h 1 0 cm. e l a s t i c rock- wool matting, I n the c a s e of an a d d i t i o n b u i l t t o t h e house, t h e

laundry and t h e food-storage room a r e i n s u l a t e d l i k e t h e l i v i n ~ rooms, vlhereas f u e l s t o r a g e and dead-storage space a r e not i n s u l - al;ed. The p a r t i t i o n s of the v e s t i b u l e , hallway and s t a i r c a s e a r e covered ;vl t h

gtt

match-boarding with f ibreboard between t h e f r m e - work and t h e boards, For laundry, t o i l e t and bathroom (provided they a r e i n t h e house and n o t i n t h e a d d i t i o n o r basement) and f o r t h e k i t c h e n ,

9"

rough p a n e l s and

3.5

m. hard f i b r e b u i l d i n g

boards a r e used. Beam-carrying i n t e r i o r w a l l s and framed

p a r t i t i o n s a r e coveFed with

$"

p a n e l s w i t h f i b r e b o a r d on e i t h e r

s i d e of t h e framework.

The f l o o r j o i s t s 26" x

7t',

a r e l a i d

60

cm, a p a r t . F l o o r l n g f e l t i s used f o r i n s u l a t i q t h e f l o o r s . For t h e j o i s t s on top of t h e basement room one l a y e r of

5

cm. f e l t i s used, whereas two

(15)

l a y e r s of 3.5 cm. f e l t a r e used i n czses where the house i s b u i l t on complete load-bearing w a l l s and two l a y e r s o f 5 cm. f e l t i n houses on columns o r on discontinuous load-bearing walls. I n t h e l a s t two house types

9"

galvanized wire mesh i s placed between t h e f l o o r j o i s t s of the basement room i n order t o p r o t e c t t h e house

a g a i n s t mice,

The j o i s t s between the f i r s t and second s t o r e y a r e in- s u l a t e d with a l a y e r of

3.5

cm. f e l t and the t o p beam with a l a y e r of 7.5 cm. e l a s t i c matting, I n t h e bathroom, t o i l e t and laundry on t h e ground f l o o r t h e r e i s f e l t i n the 1" f l o o r board between the f l o o r j o i s t s with two glued l a y e r s of asphalted cardboard extending

15

cm. up the .cvalls, The f l o o r s here a r e i n s u l a t e d with i n s u l a t i n g matting,

On the c e i l i n g s of the d i f f e r e n t s t o r e y s

2''

p a n e l s a r e used and

3"

rough panels on those of the bathroom, t o i l e t and

kitchen. The w a l l s a r e f i t t e d here with hard f i b r e p l a t e s ; otherwise match-boarding i s used. The c e i l i n g of the laundry i n t h e basement c o n s i s t s of p l a s t e r s l a b s on

3''

p a n e l s with impregnated

cardboard i n s e r t e d betwreen the p l a s t e r s l a b s and the panels,

The f l o o r boards a r e 1" x

3"

s l a s h sawn and of t h e b e s t q u a l i t y , The f l o o r i n t h e l o f t c o n s i s t s o f

2''

rough panels of second q u a l i t y ,

The r a f t e r s i n the roof covering a r e 2" x 7" and a r e 90 cm, apart, The top beams a r e 2" x 5" and the roof b a t t e n s a r e

7/8t1 rough panels. Barge boards and water b a r a r e 1". The v e n t i l - a t i n g pipes through the l o f t a r e i n s u l a t e d and cased in,

Food-storage room and basement have f o u r shelves and p o t a t o bins, There i s a rough door i n the laundry, e t c ,

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Roofing f e l t i s used a s the covering m a t e r i a l , i . e . , a l a y e r of b o t h Duplex board and a s p h a l t e d board, even on t h e s t e e p r o o f s of t h e 1 6 - s t o r e y house.

Woodwork

The o r d i n a r y ~ , v i n d o ~ - ~ s and casement windows on t h e d i f f e r - e n t f l o o r s open outward while t h e minter windows open inward, a s s p e c i f i e d i n t h e Ilorwegian Standards. The basement windovis have t h e s a s h e s opening inward, They have two panes and o u t s i d e screens, The double windows a r e i n one frame,

The main e n t r a n c e door i s of f i r , A l l t h e doors i n s i d e t h e houses a r e f l u s h doors, Small c l o s e t doors a r e rabbeted,

The s t a i r s have s t e p s 2" t h i c k , 2" i n n e r s t r i n g s , 1&" w a l l s t r i n g s and

sVt

top s t e p s ,

The k i t c h e n c a r p e n t r y can be s e e n i n t h e drawings and i s of s t a n d a r d q u a l i t y . For t h e c o u n t e r s

15"

b i r c h plpvood i s used. Rlasonry and P l a s t e r Work

Tlie c l ~ i i ~ m e y i s e r e c t e d on t h e poured foundation, t h e

b a s e

o f

t h e main f l u e being 30 cm. from t h e f l o o r . Where p o s s i b l e , the c l e a n i n g doors a r e p l a c e d i n t h e basement o r k i t c h e n , The

dimensions of t h e main f l u e a r e 1 b r i c k x 1 b r i c k , Above t h e roof t h e chimney i s b u i l t with 1 - b r i c k f l u e jambs and t h e chimney i s covered w i t h a cowl. The f i r e w a l l s a r e b u i l t according t o t h e r u l e s f o r f i r e p l a c e s l a i d down by the Norwegian F i r e Insurance Fund,

The f o u n d a t i o n ~ m l l i s p l a s t e r e d with cement mortar t o about 10 cm. below t h e ground and above t h e roof t h e chimney i s p l a s t e r e d w i t h cement mortar

1:3.

Wood-fibre cement s l a b s a r e p l a s t e r e d and basement c o n c r e t e w a l l s ~vhiteiv:lshed, Chimneys and f i r e w a l l s i n t h e d i f f e r e n t s t o r e y s a r e plumbed with f i n e p l a s t e r and t h e n broomed,

(17)

Tinsmi t h i r q

Zinc p l a t e s no. 1 2 have been alloned f o r .:!here required. The g u t t e r s a r e

4$"

and the r a i n pipes

3$".

The f l a s h i n g of the chimney i s r a i s e d 20 cm. and s e t i n the mortar j o i n t s of the

chimney, The r i d g e of the roof behind t h e chimney i s a l s o covered with f l a s h i n g . F i t t i n g s f o r the window s i l l s and door s i l l s have been included i n the estimates, Flashing i s placed on low-lying

roof boards where they a d j o i n a wall. Pent r o o f s and the l i k e a r e hooped, The v e n t i l a t i n g pipe i s run above the roof and covered with a cowl.

A 2.5 cu,m, s e p t i c tank and a

5"

concrete p i p e t o the main sewer have been allowed f o r , The p i p e s a r e estimated t o b e of the same l e n g t h a s the d i t c h e s , A

4"

s o i l pipe from the b u i l d i n g waste pipe (which i s of t h e same m a t e r i a l a s t h e s o i l p i p e ) t o t h e s e p t i c tank has been allovied f o r . The water p i p e s i n t h e house a r e of copper and have b r a s s f i t t i n g s , The p i p e s leading t o the f i r e cock a r e 1" and those leading t o an i n d i v i d u a l tapping p o i n t a r e

4"

while p i p e s a r e leadir41; t o 2-

5

tapping p o i n t s , For the

basementless houses both the water piping and the sewage p i p e s a r e insulat.ed with 20 rnm. cork moulds and asphalted, The sewage p i p e s , i n p a r t i c u l a r , a r e i n s u l a t e d and asphalted a s above and where t h e depth of the d i t c h i s l e s s than 1.60 in., o r i f the pipes a r e l a i d i n ground t h a t i s s u b j e c t t o f r e e z i n g , they a r e wrapped with

i n s u l a t i n g paper,

The following f i t t i n g s have been included: a double con- c r e t e laundry tub with two p i p e connections, a hand b a s i n , a

standard t o i l e t , a bricked-in i r o n b a t h tub, an e l e c t r i c a l l y heated 1 0 0 - l i t r e hot water tank, a swing f a u c e t serving both t h e hand

b a s i n and the b a t h tub, and a 2 0 - l i t r e e l e c t r i c water h e a t e r , A 40 cm, x 40 cm, s t a i n l e s s s t e e l s i n k with a p i l l a r f a u c e t i n the

counter has a l s o been allowed f o r a s w e l l a s a second s i n k ( f o r f i l l i n g and emptying p a i l s , e t c , ) , The l a t t e r i s of i r o n and

(18)

enamelled i n s i d e and i s provided w i t h a tap. F i r e - f i g h t i n g equipment comprising a 1" f i r e cock, 1" s t e e l p i p e and 10

m,

of 1"

hemp hose i n a s t e e l f i r e c a b i n e t h a s been included i n t h e e s t i - mates,

E l e c t r i c a l I n s t a l l a t i o n Work

I t i s assumed t h a t t h e e l e c t r i c power company i n s t a l l s s e r v i c e l i n e s , such a s underground c a b l e s , t o t h e l e a d - i n f u s e s i n each house. The f u s e box i s p l a c e d i n t h e hallway. Conduit w i r e s , t y p e s NRG and NRU a r e used f o r exposed w i r i n g . The switches and o u t l e t s a r e o u t s i d e t h e w a l l s ,

I n o r d e r t o c a l c u l a t e t h e i n s t a l l a t i o n c o s t s e x a c t speci- f i c a t i o n s of t h e system livere required, A l l t h e f i x t u r e s , b u t no l i g h t b u l b s , have been included, The laundry i s f i t t e d w i t h a washing machine of t h e s m a l l e s t type without h e a t i n g element, The w i r i n g f o r t h e k i t c h e n range i s i n s t a l l e d , b u t t h e range i t s e l f i s n o t provided.

The d r y i n g c a b i n e t i s f i t t e d w i t h r i b b e d pipes. Except f o r houses f o r s o i l - s u p p o r t e d , e l e c t r i c a l l y heated f l o o r s (found- 2 t i o n ::;etlzods

5

and G ) , t h e bsthroorns a r e provided : ~ r i l ; l ? stoves. The b e l l c i r c u i t i s connected t o t h e branch c i r c u i t .

For houses on shallow load-bearing w 3 l l s ( f o u n d a t i o n method

3)

two e l e c t r i c h e a t i n g elements a r e i n s t a l l e d i n t h e d r a i n pipes. Culvnnized p i y e s a r e l a i d between t h e connection box and

t h e d r a i n p i p e s , The main rooms i n which t h e f l o o r s a r e n o t e l e c t . r i c a l l y heated have e l e c t r i c space h e a t e r s ,

P a i n t i n a and Papering

Arm a c c u r a t e and d e t a i l e d d e s c r i p t i o n i s Ordinary f i n i s h has been chosen througllout, For e c e i l i n g coverings a r e s t a i n e d w i t h a mordant, whil k i t c h e n and bathroom a r e f i r s t primed and then t h e

supp 1 i xample e t h o s j o i n t ed. t h e e of s b e t t h e ween

(19)

t h e w a l l s and t h e c e i l i n g coverings a r e p u t t i e d twice, and s o a r e t h e f l a w s i n t h e coverings. The c e i l i n g coverings a r e then given two c o a t s of p a i n t , t h e l a s t c o a t c o n t a i n i n g approximately one- t h i r d varnish. The w a l l s of tlie hallway, v e s t i b u l e and s t a i r c a s e a r e s t a i n e d with a mordant, wllile t h e k i t c h e n and bathroom w a l l s a r e t r e a t e d i n t h e same way a s t h e c e i l i n g s . The f i r e w a l l s a r e s i z e d . The l i v i n g room and bedroom w a l l s a r e covered w i t h wall- board and papered w i t h w a l l paper c o s t i n g up t o kr. 5.50 p e r r o l l . The e x t e r n a l woodwork i s primed with o i l and given one c o a t of p a i n t .

Glazing

The g l a s s s e t i s of t h e u s u a l type and design.

S t o v e s and Valves

Valves, g r a t e s , e t c . , have been a c c u r a t e l y s p e c i f i e d . Each l i v i n g room i s s u p p l i e d with a wood stove.

Cost C a l c u l a t i o n s

The wages and t h e p r i c e s of m a t e r i a l s a r e based on those p r e v a i l i n g i n Oslo i n January 1954. The c o s t s a r e based on p r i c e s p a i d by t h e c o n t r a c t o r s with a l l t h e a d d i t i o n a l charges p e r m i t t e d by law. T r a v e l l i n g expenses and c o s t f o r moving s t o r e sheds and

shacks f o r t h e l a b o u r e r s , and otherwise q u i t e o r d i n a r y expenses such a s i n t e r e s t s on s e c u r i t i e s , temporary l i g h t i n g , water and any o t h e r unexpected c o s t s o r p r o f e s s i o n a l f e e s have n o t been included. However,

i t

i s assumed t h a t such expenses a r e t h e same f o r t h e d i f f e r e n t t y p e s of house designs.

The c o s t s f o r t h e d i f f e r e n t t y p e s of work have been

s p e c i f i e d and assembled i n a table. I n a d d i t i o n t o t h i s , t h e groups f o r t h e c o s t of f o u n d a t i o n work, c a r p e n t r y and e l e c t r i c a l work were subdivided i n t o subgroups. This s u b d i v i s i o n i s made such a s t o provide t h e b a s i s r e q u i r e d f o r a c l o s e s t u d y of t h e i n d i v i d u a l p r i c e s involved.

(20)

(21)

For the houses built on column foundations (~~ietholl 1) the cost of steel bearns has been included in the item "foundation mall and insulation", although, strictly speaking, beams should be listed under carpentry.

The principal costs for the

30

design types are shown on a cost sheet ('Table

I),

and supplementary information is given below*

At the bottom of the cost sheet the larger floor area of the utility rooms in design ty-pes B and

E

has been taken into

account as well as the operating expense of the heating cable for houses vii th shallow load-bearing walls (foundation method

3).

The fact that house designs B and

E

have food-storage rooms of approximately 6.2 sq.m. (including the stairs) while the other design ty-pes have f ood-storage rooms of approximately

3.6

sq.m, was roughly estimated to involve an extra of kr.

150.-.

Therefore, this item should be deducted from the building costs for design types B and

E,

before these are compared with other types, regardless of the foundation method,

For the heating cable required in houses built with shallow load-bearing walls (foundation method

3)

the current con- sumption is estimated at 20 w e per 1

m.

of foundation, This

additional expense has been broken down for the different design types as folloiris:

Design type A3 B3

D3

E3

Peak consumption (in

w.

)

950

900

850

750

Annual consumption in kr,

114. -

108.

-

102.

-

90. -

(estimated)

Annual consumption finan- 2,950.

-

2s700.

-

2,550.

-

2$ 25oe

-

ced at

4%

(which is the

75-year annuity of

3.75%

(22)

Before t h e r e s u l t s f o r the d i f f e r e n t houses a r e compared i t would be reasonable t o take t h i s rough c o r r e c t i o n i n t o account.

Since no a c t u a l data a r e a v a i l a b l e a s y e t , higher or

lower c u r r e n t consumption f o r design types with foundations accord- i n g t o methods 5 and 6 ( e l e c t r i c a l l y heated f l o o r s l a b ) was not taken i n t o account.

The D i f f e r e n t Design T.mes Compared with One Another

The p r i c e s of the d i f f e r e n t houses a r e compared below, The p r i c e s given i n Table I a r e used a s the b a s i s of t h i s com- p a r i s o n of the b u i l d i n g c o s t s f o r t h e d i f f e r e n t types (including

t h e c o r r e c t i o n s explained above).

I n order t o have a c l e a r b a s i s of comparison, the p r i c e s below have been arranged i n the same order a s the design types i n Fig, 1.

Table I1

Costs i n kroner, arranged according t o design type and foundation method

Design type Foundation method A B C D E F 1. Columns 43,763 44,207 42,015

449404

44,822

42,142

2, Discontinuous 46,420 46,270 42,652 46,542 46',440 42,279 load-bearing w a l l s 3. Shallow load- 46,851 47*301 47,164 47,564 bearing w a l l s

4-

Complete load- 47#790 47,625 43*437 47,976 47,861 42,832 bearing w a l l s 5. Concrete f l o o r 48,519 49,367 47,532 48,446 s l a b 6, Concrete f l o o r 51,870 52,528 50,392 51, 109 s l a b with p e r i - p h e r a l f o o t i n g

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I f , f o r c l a r i t y , t h e t a b l e i s rearranged so t h a t 1 de- n o t e s t h e cheapest design type and 2 the second cheapest, and so on, then the t a b l e has the f o l l o ~ v i n g appearance:

Table I11

Costs i n kroner ( 1 = cheapest design type 30 = most expensive design type)

Foundation method Design type

1. Columns 2. Discontinuous load-bearing 12 11

4

14

13

3

w a l l s

3.

Shallow load-bearing w a l l s 15 17 16 19

4.

Complete load-bearing w a l l s 21 20

6

23 22 5 5. Concrete f l o o r s l a b 25 26 18 24 6, Concrete f l o o r s l a b with 29 30 27 28 p e r i p h e r a l f o o t i n g

I t i s evident from Table I V t h a t the p r i c e s have been d i v i d e d i n t o t h r e e groups, Group 1, comprising the t e n cheapest

design types, c o n s i s t s of houses on column foundations and houses with a l l the u t i l i t y rooms i n the basement, The l a s t group with

the f o u r most expensive design types includes houses with s o i l - supported concrete f l o o r s l a b with p e r i p h e r a l f o o t i n g (foundation method 6).

The second group thus c o n s i s t s of 16 design types, The p r i c e s from house t o house d i f f e r so l i t t l e here t h a t the s l i g h t e s t change i n the s p e c i f i c a t i o n could a l t e r the sequence, Within t h i s group the p r i c e s have been arranged i n such a way t h a t a small

(24)

Table

IV

Design types arranged according to price

-- - - -

(25)

The results of the cost calculations stress the import- ance of the house type and foundation method. This is something

everybody with experience in the building trade knows in advance. It is nevertheless interesting to note that these t n e s of one- family houses, which are designed so as to be as similar as possible in facilities and floor area, may differ by as much as kr. 10,000.- in building costs. The most expensive design type

costs 25 per cent more than the cheapest. The difference in price is due to the design chosen and foundation method used. Therefore, this is discussed in greater detail.

Comparison of the Design Types

The bases for the calculations

-

and the calculations themselves have been presented in such a way that those interested may analyze the prices, and it is to be hoped the information may prove useful to thern. It must be emphasized that the calculations apply only to the special conditions rr,entioned, e,g. that the

houses are built on sites without bedrock and that they are heated by a combination of wood stoves and electric heating equipment, Nevertheless the calculations provide individual d a t ~ which may have some general v~lidity.

Before compfl-ring the results the main conclusions should be pointed out:

1. The six design types with all the utility rooms in the basement are the cheapest.

2. The difference in price for the houses with partial basement consisting only of a food-storage room and

those entirely without basement is slight.

3.

The 1-storey houses shorv the greatest price fluctuations, Their price is lowest when the least expensive foundation methods are used and highest for the most expensive ones,

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Design T.ypes with all the Utility Rooms in the Basement

Hitherto it was customry to place all the utility rooms in the basement and, therefore, it would be interesting to compare such a design type with houses where all the utility rooms, or at least most of them, have been moved to the ground floor.

An

American investigation of one-family houses with or without basement supplies information on the relevant price levels

ln the U,S,A.

(3),

The houses in question had been built on soil- supported concrete floor slabs, which were unheated, Under conditions which resembled those OF the present investigation to some extent the prices were calculated for different design solutions, In this special case the one-storey design type could be built without basement and with the utility rooms within the house in a

separate wing having a floor area of up to 28% of the total living space of the house, This type of house was no more expensive than one with a basement, In another case the utility rooms and the living area in the basementless house had been drawn into a simple rectangular design, The utility rooms here occupied

31%

of the living space without making this house rnore expensive than one with a basement.

In the house t m e s on which the present investigation is based the addition containing the utility rooms constitutes 29%

of the living space for the design types 11 _anci

_D.

_{This are:r for}

the utility rooms corresponds to the partial bilsel~ient of the 1$- storey house design type F.

Frequently the floor area of the utility rooms in basementless houses is excessively small, and in many houses

essential utility rooms are simply dispensed with, Strictly speaking, therefore, the prices of such houses should be compared with those of conventional houses with basements, On the other hand, a utility-room addition containing 29% of the living space is rather

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The cost calculations show that the six houses with all the utility rooms in the basement are the cheapest of the house ty-pes investigated.

The prices of houses of the same type of foundation may be compared as far as the unexcavated parts are concerned. The

greatest difference in favour of basementless houses occurs when these are supported on complete load-bearing walls, while the least difference occurs for column foundations, The difference between design ty-pes

D4

and

F4

is as much as kr.

5,144,-

while it is only kr, 1,748,

-

for A1 and C1,

The possibility of fitting the utility rooms in basementless houses into a smaller area and of saving some space by dis- pensing with the stairs has not been taken into account. Therefore, no categorical statement should be made against basementless houses on sites without bedrock, but it may be considered an established fact that it is difficult for the basementless house to compete economically with house types in which the utility rooms have been placed in the basement, For to do so a cornpact and well planned design is required and such houses must be built rationally and in an inexpensive way. If built on sites with bedrock, of course, the basementless house has the advantage over other ty-pes.

Houses without Basements or Houses with Partial Basement for Food Storage Onlg

While the houses with the utility rooms in the basement decidedly were the cheapest under the conditions on which these calculations were made, the difference in price for the basementless houses,

A

and

D,

and the houses with partial basement, B and

E , is not great,

However, when particularly cheap foundation methods are used the house entirely without basement seems to be more advantageous economically than a house with a partial basement.

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The comparison shows that f oundti tion methods 1 (colwms) and

3

(shallow load-bearing walls) are particularly cheap. lihen these methods are used the basernentless houses cost from 400 to

500

kroner less than the houses with partial basements. For the other foundation methods the results vary, but the difference is unimportant in any case.

As mentioned above, it had been assumed for the calculations that the food-storage room is lowered in basementless houses with wood floorings (foundation methods 1- 4, cf. Fig. 10). This more complicated type of food-storage room costs considerably r:lore

than where the wood floorix can be insulated throughout.

The increment in the price of the different types is: A1 and Dl: kr.

686.-

A2 and D2: kr,

684.-

A3 and D3: kr. 223.-

A4

and D 4 kr, 684,-

The lower price for A3 and D3 is due to the sun11 depth of foundation for these houses.

Cornparison of the one-storey houses on column foundations ( ~ l and ~ 1 ) sho~us that house A1 (entirely without bosement) is the cheapest. If this house is built without lowering the food-storage roorn, i.e,, with wood floori-w throughout, il;s price will be lower b y kr. 1,130.- than that of house B1, where the food-storage room is in the basement, This gives an idea of how much could be in- vested in a refrigerator when A1 is built with wood flooring in

the food-storage room, unless this house is more expensive than B1. One-Stores and 1:-storey Houses

Based on the average prices of the different design types the 1;-storey houses are less expensive than the corresponding one- storey houses, but the difference is slight and the trend is not ty-2ical.

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However, f o r t h e f o u n d a t i o n methods t h a t a r e c h e a p e s t t o apply t h e one-storey house t m e s a r e t h e cheapest. This i s c l e a r i n t h e c a s e of foundation method 1 ( c o l ~ ~ m s ) b u t a l s o a p p l i e s t o method

3

( s h a l l o w load-bearing w a l l s ) . Between F1 and C 1 (houses with basements) the d i f f e r e n c e i s only kr, 127,-. This i s due t o the f a c t t h a t o n l y one sraall p o r t i o n of t h e ground p l s n i s n o t excavated. Between t h e o t h e r d e s i g n ty-pes t h e d i f f e r e n c e i s about kr. 600.

-

f o r houses on column f o u n d a t i o n s , b u t only o n e - h a l f t h i s arnount f o r houses w i t h d i s c o n t i n u o u s load-bearing walls.

For many of t h e design types t h e one-storey houses a r e cheaper t h a n t h e corresponding d e s i g n ty-pes of t h e 1 s - s t o r e y houses. For exalrlple, t h i s a p p l i e s t o a l l the liouses h a v i r ~ wood f l o o r i n g

( f o u n d : ~ t i o n methods 1-

4 )

and no u t i l i t y rooms i n t h e basement.

The d i f f e r e n c e i n p r i c e m:<y be small, b u t t h e r e i s n e v e r t h e l e s s good reason f o r n o t i n g i t , The 1 s - s t o r e y houses a r e g e n e r a l l y thought

t o b e cheaper than t h e one-storey houses w i t h the same l i v i n g space. This b e l i e f i s based on experience conventional houses with basements,

It i s probable t h a t a n exceedingly cheap o r exceedingly expensive f o u n d a t i o n method g r e a t l y a f f e c t s t h e p r i c e of the one- s t o r e y houses. For t h e most expensive f o u n d a t i o n methods, i . e , , uhere t h e houses have s o i l - s c p p o r t e d lizated c o n c r e t e f l o o r s l a b s ,

t h e one-storey houses a r e more expensive t h a n t h e corresponding d e s i g n ty-pes oi' t h e l & - s t o r e y houses,

The c o s t c a l c u l a t i o n s f o r t h e r o o f s included t h e r o o f i n g f e l t i n a l l cases. I n t h e d e s i g n types OF t h e 16-storey houses t h e roof over t h e main p a r t of t h e house s l o p e s

45

degrees. T h i s i s almost too s t e e p a s l o p e for* f e l t roof-covering. If t h e roof i s t o b e covered with cement r o o f i n g - t i l e s i n s t e a d , t h e p r i c e s of a l l t h e

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Comparison of t h e Foundation hlethods Comparison sho~rfs t h a t t h e r e a r e g r e a t d i f f e r e n c e s i n t h e c o s t s of t h e d i f f e r e n t f o u n d a t i o n methods i n v e s t i g a t e d , The average c o s t s ( i n k r o n e r ) of t h e d i f f e r e n t f o u n d a t i o n methods a r e a s f o l l o w s : F o r d e s i g n ty-pes A , B, D and E C and F 1, Colur;uls

4 - 4 9

299.0 42,079.

-

2. Discont,inuous l o a d - b e a r i n g w a l l s 46, 418e

-

42,466.

-

3.

Shallow l o a d - b e a r i n g : ~ ; a l l s 47,220.

-

4.

Complete load-bearing 1 ~ 1 a l l s 47,813.

-

43,

125.

-

5.

Concrete f l o o r s l a b 40,466.

-

6, Concrete f l o o r s l a b ~ i t h p e r i -

51,475.

-

p h e r a l f o o t i n g

T a b l e s I1 and I11 show t h a t i n d i v i d u a l d e s i g n t y p e s on ''cheap" f o u n d a t i o n s may b e more expensive t h a n o t h e r d e s i g n ty-pes oil ttesy,ensive" f otmdations. F o r example, d e s i g n t y p e

C 4

i s cheaper t h a n A l . But i f t h e f o u n d a t i o n metilods a r e compared from d e s i g n type t o d e s i g n t y p e , t h e houses employing f o u n d a t i o n method 1

(columns) w i l l b e cheaper t h m t h o s e errrploying rnethod

4

(complete l o a d - b e a r i n g w a l l s ) i n a l l c a s e s ,

T h e r e f o r e , i f ' i n what f ' o l l o n s a f o u n d a t i o n method i s shown a s c h e a p e r o r more e x p e n s i v e t h a n a n o t h e r one, i t i s t a k e n f o r

g r a n t e d t h a t t h e conrparison i s f o r one and t h e same d e s i g n type and under t h e c o n d i t i o n s l a i d down.

The f o l l o w i n g f a c t s t h e n emerge:

1. Foundation method 1 (columns) i s t h e c h e a p e s t of t h e methods i n v e s t i g a t e d .

2. Foundation method 2 ( d i s c o n t i n u o u s l o a d - b e a r i n g w a l l s ) i s t h e second c h e a p e s t ,

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3.

For f'ounclation n e t h o d s

3,

4

and

5

t h e p r i c e s a r e l e s s c l e a r l y d i f f e r e n t i a t e d . The o r d e r a s determined b y t h e average p r i c e s i s n o t i n v a r i a b l e . On t h e b a s i s of t h e average p r i c e s , how- e v e r , foundat-ion method

3

( s h a l l o w l o a d - b e a r i n g vvalls) i s t h e t h i r d c h e a p e s t , f ollolr~ed b y method

4

(complete load-bearing ~ ~ a l l s ) and method

5

( s o i l - s u p p o r t e d , e l e c t r i c a l l y h e a t e d c o n c r e t e f l o o r s l a b )

I n t h a t order.

4.

Foundation method

6

( s o i l - s u p p o r t e d , e l e c t r i c a l l y h e a t e d c o n c r e t e f l o o r s l a b w i t h p e r i p h e r a l f o o t i n g down t o t h e un- f r o z e n ground) i s t h e rliost e x p e n s i v e method of t h o s e i n v e s t i g a t e d .

The d i f f e r e n c e i n p r i c e s of t h e houses on column found- a t i o n s and t h o s e on d i s c o n t i n u o u s l o a d - b e a r i n g w a l l s a r e marked. I n t h e c a s e o f t h e b a s e m e n t l e s s houses t h i s d i f f e r e n c e i s a s much as lcr. 2,657.- f o r t h e o n e - s t o r e y house ( A ) and k r , 2,138,- f o r t h e l & - s t o r e y house ( D ) , For t h e houses w i t h a l l t h e u t i l i t y r200ias i n t h e basement t h e f o u n d a t i o n methods a r e e c o n o ~ r i ~ c a l l y n o t a s import- a n t a s f a r a s t h e unexcavated p a r t i s concerned. The d i f f e r e n c e h e r e 1s o n l y kr.

537,-

f o r t h e one-storey house

( c )

and lcr.

137.-

f o r t h e 1 3 - s t o r e y house ( F ) .

There i s a l s o a d i s t i n c t thougl? rrot a s g r e a t a p r i c e dlff e r e n c e between f o u n d a t i o n s on d i s c o r ~ t i n u o u s l o a d - b e a r i n g w a l l s (method 2 ) and f o u n d a t i o n methods coming a f t e r ( 2 ) i n p r i c e .

The d i f f e r e n c e i n t h e a v e r a z e p r i c e s f o r t h e houses ~ i t h f o u n d a t i o n methods

3

t o

5

i s a p p r o x i m a t e l y kr. 1,250.- f o r d e s i g n t y p e s A, B , D and E. The p r i c e s of t h e house t y p e s on s h a l l o v ~ l o a d - b e a r i n g w a l l s ( f o u n d a t i o n method

3)

depend g r e a t l y on t h e p r i c e of t h e e l e c t r i c c u r r e n t znd t h e c u r r e n t consw~aption of tlre h e a t i n g c a b l e s a t t h e f o u n d a t i o n s . The c o s t of o p e r a t i n g t h e h e a t i n g c a b l e c a n o n l y b e e s t i m a t e d roughly. The comparison shows t h a t t h i s found- a t i o n method i s s l i g h t l y cheaper throughout t h a n i n c a s e s where

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(method 4 ) . The d i f f e r e n c e i s ' g r e a t e s t i n t h e case of the

basementless house ty-pes, b u t even f o r t h e one-storey house type

A i t i s l e s s than kr. 1,000.-.

The comparison shows t h a t i n c a s e s involving s m a l l ground p l a n s , i.e., 1;-storey houses, an e l e c t r i c a l l y heated c o n c r e t e

f l o o r s l a b m y be more advantageous a s a f o u n d a t i o n lr~ethod t h a n complete load-bearing w a l l s , b u t t h i s does n o t apply t o l a r g e ground p l a n s , i. e.

,

one-s t o r e y houses.

This i s probably c o n t r a r y t o what i s g e n e r a l l y b e l i e v e d , The s o i l - s u g p o r t e d , heated c o n c r e t e f l o o r s l a b was f r e q u e n t l y thought t o c o n s t i t u t e a cheap f o u n d a t i o n f o r a one-storey house,

The c o s t a n a l y s i s shows t h a t b o t h foundatiolzs

-

coimplete load-bearing w a l l s and soil-supported, heated c o n c r e t e s l a b

-

a r e corrrparatively expensive methods, The one-storey, basementless house on complete load-bearing n a l l s ( t y p e A ) c o s t s approximately kr. 4,000.- more than t h a t on a column f o u n d a t i o n (ty-pe Al).

The f a c t t h a t t h e d i f f e r e n c e i s l e s s when o r d i n a r y d e s i g n t y p e s w i t h t h e u t l l i t y roorns i n t h e basement a r e compared a p p l i e s h e r e a s well. The d i f f e r e n c e between

C 4

ancl C 1 ( t h e one- s t o r e y house ty-pes) i s kr. 1,422.- while i t i s only kr. 690.- be- t ~ r e e n F4 and F1 (the 1;-storey houses).

Therefore, c o n s i d e r a b l e thought should be g i v e n t o the choice of t h e foundation method, e s p e c i a l l y i f not a l l t h e u t i l i t y rooma a r e t o b e placed i n t h e basement.

Close Analysis of t h e Foundation Methods

I n o r d e r t o ap2ly t h e r e s u l t s t o p r a c t i c e t h e foundation methods must be analyzed on t h e b a s i s of t h e above statements,

The two cheapest methods, namely, column f o u n d a t i o n s and d i s c o n t i n u o u s load-bearing w a l l s have been used on occasions when

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it vms a :[latter of reducing the building costs, Nevertheless the majority of one-family houses continued to be built with fully

excavated basements or corrplete load-bearing ;.ialls down to the

un-

frozen ground,

Columns and discontinuous load-bearing walls are techni- cally simple constructions which favour a rational design It is a disadvantage, however, that the flooring is exposed to cooling from belov?. This makes heavy insulation essential as a l l as the dol-award extension of the outside sheeting layer on the external walls, At the same time the conduits must be insu'lxtedl carefully, Therefore, these foundatioii methods are less suitable for exposed sites with a great deal 02 snow in winter. Furt.herinore, a galvanized wire mesh between the floor joists of the bctsement is required in order to protect the house against mice.

Cornparison shows that bnsementless houses and column f'oundations go well together.

It seems unrealistic to build on sh:illow load-bearing

walls, which must be protected against rrost by electric~illy heating the soil on which they are resting, The cost of constructiol? is slightly reduced, but the annual costs are scarcely less than for coniplete load-bearing walls. The fuel consumption is another factor against this foundation method.

The conventional comlcte load-bearing walls frequently constitute a logical foundation method- Where a larger part of the ground plan of a one-family house has a basement not much is saved by using a different foundation method for the unexcavated part. With adequate ventilation and height of the excavation this type of foundation is all right. Complete load-bearing walls protect the flooring against cooling and are suitable for exposed sites.

However- for design types whose utility room area in the basement is small the choice of the foundation method for the

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mtxcav.s.tccl p-i-1; does ;lot ai'fect the p r i c e t o an e x t e n t which would j u s t i f y seeking a cheaper f o u n d s t i o n method.

The c o n s t r u c t i o n s which n e r e cost-analyzed f o r houses with s o i l - s u p p o r t e d c o n c r e t e f l o o r s l a b a r e only t s o of m r m y

p o s s i b i l i t i e s , Such houses rnay b e d e s i ~ n e d f o r hot-:vater o r hot- a i r h e a t i n g i n t h e c o n c r e t e s l a b op i n t h e i'loo-1 o r ~ ? ~ i t i l o u t a s p e c l a 1 h e a t i n g system i n t h e f l o o r i t s e l f . Both Cesiglis l n v e s t i - gated have a s o i l - s u p p o r t e d , e l e c t r i c a l l y heated c o n c r e t e f l o o r s l a % , There d e f i n i t e l y i s sorile p r i c e d i f f e r e n c e betT;ieen tiiese

tmes sild t h e o t h e r v a r i a t i o n s , b u t t h e foundation neth hods chosen h e r e should n e v e r t h e l e s s g i v e a u e f u l p i c t u r e of t h e economic c o n d i t i o n s .

I t would appear from t h e c o s t a n a l y s i s t h z t t h e two f o u n d a t i o n methods which have p e r i p h e r a l f o o t i n g s down t o t h e un- f r o z e n ground and I-rave heated, s o i l - s u p p o r t e d c o n c r e t e s l a b s a r e

too expensive under our c o n d i t i o n s , r e g a r d l e s s of the h e a t i n g system f o r the s l a b s .

However, t h e c a l c u l a t i o n s show t h a t tlie i n v e s t i g : ~ t e d f'oul~dntion method w i t h s o i l - ~ ~ p p o ~ t e i i : ~ n d heated c o n c r e t e f ' l o o ~

sl:?,73 and ~ i t h g r e a t l y reduced depth of foundz~tion m:?y w e l l compete

i n p r i c e with t h e conventions1 foundation methods. T,?evertheless, t.he heated, soil-suppor.tizd c o n c r e t e f l o o r slab must be considered a c o r i p a r i t e l y expensive c o n s t r a c t i o n ,

The house w i t h s o i l - s u p p o r t e d f l o o r rnust be designed i n a simple and r a t i o n a l way i n o r d e r t o beco~ile economically more advantageous t h a n a house w i t h a conventional i'ouilci:~l;ion, The r e s u l t s obtzined from t h e i n v e s t i g a t i o n seem t o b e a r out t h e con- t e n t i o n t h a t t h e h e a t i n g system should b e s i m p l i f i e d and should n o t be grouted i n t o t h e f l o o r , A cheaper f l o o r covering on t h e poured c o n c r e t e s l a b , o r a change-over t o another f l o o r design, r:;ight have some e f f e c t on t h e p r i c e s . Generally speaking, i t

should b e p o s s i b l e t o evolve methods of c o n s t r u c t i o n which a r e more t,or;rpe-t,itive than t h e two rnetllods i n v e s t i g a t e d .