Housing standards: a comparison of the old and new requirements

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Canadian Builder, 12, 3, pp. 50-52, 1962-04-01

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Housing standards: a comparison of the old and new requirements

Hansen, A. T.

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no. 137

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HOTSINC STANDARDS

-A CO1VIP-ARISON

OF THT OLD

AND NEW REQI]IREMENTS

NATTONAL

RESEARCH

COUNCIL

CANADA

DIVISION OF BUILDING RESEARCH

by

A. T. Hansen

ANALYE:.#

Reprinted From

Canadian Builder, Vol. rz, No. 3 March 1962, p. 5o-52

Technical

Division of

Paper No.

of the

Building R

3

trj|tlllilll

MAY 55 1eE2

NATIiNJ|L RESEI\RCH COt'ldcll.

iltl

OTTAIUTA

NRC Associate Committee on the Na-tional Building Qode. This supplement,

Early in (1962), Supplement N'o. 5 to the Building Code, "Housing - Canada, 1962", the auspices ol the was published

which includes 9: Housittg, of the National B Code was over three years tn and is the result ol the work of committees whose individuals of varied tl'te nation. Supple-interests from

the Housing The new Housing Standards have adopted by CMHC lor use in houses under the National

Housing Standards are issued in two slightly different forms: a red-covered do-cument intended lor use primariLy by mu-nicipalities who have adopted the National

Building Code; and a blue-covered one that will be used by CMHC. Both books are identical in content except the blue-covered book contains an additional seven pages at the front outlining additional requirements and administrative clauses for houses built under the National Hous-ing Act.

The f ollowing inlormation has been prepared to acquaint those using the new Standards with some of the more signif-icant changes in relation to former re-quirements. The lollowing comments by no medns cover all the changes, but are intended to spotlight the more important differences.

In the following comparisons the page number referred to in the New Housing Standards appears after the subject head-ing for convenience in findhead-ing the require-ment.

T h e a u l h o r o f t h i s a r f i c l e . A . T . HANSEN, B.Sc., Eraduated from the University of New Brunswicl in 1952 w i t h a d e g r e e i n c i v i l e n g i n e e r i n g a n d i n 1 9 5 4 o b t a i n e d a d e E r e e i n m e c h -i n c a l e n g -i n e e r -i n g . H e -io-ined the D-iv-i- Divi-s i o n o f B u i l d i n E R e Divi-s e a r c h in 1 9 5 4 . A Divi-s a research officer wiih lhe Housing S e c t i o n , h e h a s b e e n c l o s e l y a s s o c i a f e d with the Division's work on Can,ada's H o u s i n E S t a n d a r d s .

requirements

Minimum room heights have been re-duced generally. Minimum oeiling height over at least'75Vo of the floor areas in living rooms, dining rooms, kitchens, or such spaces in combination, is now 7-ft. 6-in., while in bedrooms a 7-ft. 6-in. min-imum height of ceiling must be provided over 5O7o of the required floor area. Clolhes Closels (p.291

Although the minimum floor areas of clothes closets is unchanged at 6-sq. ft., the minimum depth of closet has been reduced to l-ft. 2-in. provided the width of opening is at least 4-ft. For lesser openings the minimum depth remains at 1-ft. 10-in.

Noturol Yenlilolion (p.35. 36)

Requirements for openable window areas have been changed from 5%o of the floor area of the room served to 3-sq. ft. per room, except in bathrooms (l-sq. ft.) and in living rooms and living-dining rooms where no natural ventilation is re-quired (the same as in the previous Stand-ards).

Ventilation of crawl spaces used as warm air plenums is no longer required, but the ventilation of other types of crawl spaces has been increased so that 2-sq. ft. of vent area is required per 1,000-ft. of

Housing Standards-A comparison of the

old and new requirements

Conrparison

of

A new table of minimum room sizes has been provided and presented in such a way that the minimum areas for com-bination rooms can be quickly computed by adding the minimum spaces permitted for the particular functions.

In general, room areas have been slight-ly reduced in relation to the 1958 require-ments but the room areas are based on dimensions between finished wall surfaces and are not taken to the faces of the studs as was formerly the case.

Bedroom areas may be reduced when built-in bedroom cabinets are provided; minimum requirements for such cabinets are provided. There is a slight difference between CMHC minimum bedroom sizes and those listed in the Standards and this should be checked by those building under the National Housing Act. In general, minimum room dimensions are identical to those in the former Housing Standards with the exception that the minimum di-mension for bedrooms, other than the main bedroom, have been reduced to 5-ft. lGin. and the hallways to Z-ft. 10-in. The minimum dimensions for CMHC pur-poses, however, are still 6-ft. 10-in. and 3-ft. respectively. The minimum dining area dimension has been reduced from 7-ft. 8-in. to 7-ft. 6-in.

crawl space floor area as compared to l-sq. ft. per 1,000-sq. ft. in the 1958 edition of the Standards.

Mechonicql Yenlilofion (p. 351

Mechanical ventilation may be substi-tuted for natural ventilation in all rooms provided the system has the capacity to produce at least one air change per hour. With such a system, all windows could be fixed.

Window Areos (p. 34, 351

A new requirement has been added for windows shielded by roof overhangs ex-ceeding 6-ft., e.g. carport roofs. Such win-dows, if constituting part of the required natural lighting, must have an area equal to 20Vo of the floor area of the room served if any part of the window is more than S-ft. from the corner of the house. The requirement for most habitable rooms remains at lOVo. Laundry areas or recrea-tion rooms in basements must now have a window area not less than 4Vo of the floor area served.

Fire Slopping (p. 371

An additional requirement is that fire stopping must also be installed between floor joists at their ends and over sup-ports in concealed spaces (such as in the second floor in two-storey houses). Fire Seporofions Belween Goroges o n d H o u s e s ( p . 3 7 , 3 8 )

Fire resistance between houses and at-tached or built-in garages has been re-duced from l-hr. to /z-hr. where the room adjacent to the garage is not a bed-room. The fire resistance for doors be-tween attached garages and houses has been reduced from l-hr. to 20-min. Fire Resistonce Rolings (p.45 to 521

A total of 8 pages is devoted to a list-ing of the fire resistance of various types of wall and floor constructions. These tables also indicate constructions having a 45-decibel sound transmission loss. The listing is much more comprehensive than the list in the 1958 Housing Standards and should be of considerable assistance to builders.

Side Ycrd Gleoronces (p.39)

The requirements for side yard clear-ances have been completely revised. The 1958 Standards required a minimum 4-ft. distance from the lot line for one-storey houses and 6-ft. clearance for two-storey houses. The new requirements are more varied and must be studied in detail to gain a complete understanding of them. Very briefly, the new requirements mean this: Houses may be built on the lot line provided the wall has a l-hr. fire resist-ance over the entire face. Walls less than 4-ft. from the lot line must have a 3/+-hr. fire resistance over the entire wall. Any part of a building, including the eaves, within 2-ft. of the lot line must have in-combustible cladding. Walls 4-ft. or more frorn the lot line rnay contain openings but a comprehensive table is provided Iimiting the maximum area of such

open-ings depending on the area of the wall, the ratio of length to height of walls and the distance to the lot line. For those building under the National Housing Act, there are additional requirements for ade-quate clearances between buildings, for access for maintenance. In the case of bungalows this is 4-ft. and for houses of 2 or more storeys, 6-ft.

Foundolion Wotls (p. 601 ; A new table listing the minimum thick-nesses of foundation walls for various heights of backfill is included. This table is intended for use with average soil con-ditions and is applicable to foundation walls not more than 8-ft. high. The table differentiates between walls laterally sup-pcrted at the top by the floor system (the most common arrangernent) and those not supported. Six-in. solid concrete walh are now permitted if the height of backfill above the basement floor is not more than 5-ft. for walls laterally supported, and,ZVz-ft. if the walls are unsupported. Six-in. thick unit masonry walls are also permitted, provided the height of fill above the basement floor does not exceed 2-ft. for both laterally supported and un-supported walls. This will be of particular significance with crawl space construction. Eight-in. unit masonry walls are now per-mitted if the height of backfill does nor exceed 4-ft. for walls supported at the top, or 2-ft. 6-in. if tle walls are unsup-ported. Acceptable lateral suppo.rt includes the conventional type of construction with the floor joists supported on a plate an-chored to the top of the wall. To be laterally supported, walls must not con-tain openings greater than 4-ft. in lengtb. and at least 75Vo of the wall length must be solid. Another important change in the new Standards is that intermediate founda-tion wall support using wing walls, but-tresses, etc., is no longer required, regard-less of the wall length.

Sill Plates (p. 78, 80, 811

As an alternative to capping the top course of hollow block foundations, a sill plate the full width of the block may be used, or if the exterior siding overlaps the exterior foundation wall at least /z-in., a standard 2 by 4 sill may be used without additional capping. As an alternative to bedding the sill in mortar, the sill may be placed directly on the foundation if the top of the wall is level, provided the junction between sill and foundation is caulked. Anchor bolts may now be 1y'2-in. diameter spaced not more than 8-ft. o.c. Basemenf ond Cellor Columns

( p . 6 1 . 6 2 )

Pedestals are no longer required beneath columns, but wood columns must be sep-arated from the concrete slab by a damp-proofing material.

Interior Pcrtiiions for Bosemenls. Cellors cnd Growl Spoces lp. 521

Interior masonry load-bearing partitions may now be 4-in. thick provided the walls are not more than 5-ft. 6-in. high (which would apply in most crawl spaces), or 6-in. for walls up to 9-ft. high.

Wood stud load-bearing basement parti-tions may now consist of 2 by 4 studs spaced 24-in. apart in bungalows or 16-in. apart in two-storey houses where only limited attic storage is involved and pro-vided the roof load is not supported by the partition. Such partitions need not be supported on a raised base as previously required but must be separated from the slab by a damp-proofing material. Moisture Proleclion for Bosenenl S l o b s ( p . 5 4 1

As an alternative to the standard re-quirement for 5-in. of granular fill beneath basement floors, builders may now use 4 mil polyethylene beneath the slab. In some cases this may prove to be a more economical alternative.

I n s u l o l i o n ( p . 5 9 1

The minimum degree of thermal insula-tion is now specified in relainsula-tion to climate on a degree-day basis. Previously, the minimum requirements were the same for all of Canada. While the minimum ther-mal resistance of 6.67 units is stiLl required, it now applies to only those areas having 8,000 mean annual degree days or less such as the southern and eastern portion of Nova Scotia, the southero portion of Ontario including Toronto, and the west-ern and southwest-ern parts of British Colum-bia. Where the number of mean annual degree days is over 8,000 but not more than 11,000, 8.33 units of resistance is re-quired. This would apply to P. E. I., N. B., northwestern N.S., southern Quebec, the Southern portion of Ontario lying north of Toronto, the southern parts of the Prairie Provinces and most of northern B. C. Where the degre,e days exceed 11,-000, 10 units of thermal resistance are re-quired. A typical wood-frame wall with 2-in. of mineral wool insulation will pro-vide over 10 units of thermal resistance. Windows (p. 73)

Windows must now be built to restrict the air infiltration around them to 0.75-cu ft. of air per minute per foot of crack (as determined when tested according to clause 5. 3. I in CGSB specification 63-GP-3).

D o o r s ( p . 5 l

Only one exterior exit is now required. If a second entrance is provided, it can presumably be through an attached garage or through a sliding door since the second door is not a required exit.

Mosonry Wolls Above €rode [ p . 7 8 . 7 i 1

Exterior masonry walls above grade may now be only 6-in. thick for walls not more than 9-ft. in height to the eave, and 15-ft. in height to the peak at the gable ends. Eight-in. masonry walls may be 35-ft. in height. This applies to block as well as brick. Interior load-bearing walls may now be 6-in. thick for walls up to 9-ft. in height, or 8-in. thick for walls up to 35-ft. in height. Interior non-load-bearing walls may be 3-in. thick if they are supported either horizontally or ver-tically at intervals not exceeding 9-ft.

Bosemenl Beons (p. 213, 214, 217, New span tables have now been pro-vided for both steel I bearns and wood beams for both one- and two-storey houses. In the wood beam table, spans are provided for various species as well as several grades of lumber. In general, the allowable spans are greater than shown in the more limited table in the 1958 Housing Standards.

Spon Tobles for Joisls qnd Roflers ( p . I 7 4 f o 2 0 9 1

A completely revised set of span tables for joists and rafters has been provided and represents one of the most important changes in the new Housing Standards. There are now 36 pages of span tables as compared to only 3 pages in the former Housing Standards. There are several rea-sons for the increase in the number of tables, the chief one being that they have now been worked out for various grades of lumber whereas the 1958 Standards were based on only a single grade. This will be of particular advantage in select-ing the most economical lurnber to span a given distance. Another reason for the increase in the number of spans is that the tables are worked out for various load and deflection requirements which are much more extensive than was for-merly the case.

Design floor loads, for example, may be less in bedrooms than for other parts of the house (30-psf. live load in bed-rooms, 40-psf. live load in other areas) and tables have been worked out accord-ingly.

Ceiling joist spans have been prepared for cases where limi ed attic storage is involved (the usual case) and for attic storage where the attic is accessible by a stairway.

In the case of roof framing, spans have been prepared for 30-, 40-, and 50-psf. snow loads whereas the requirements in the 1958 Standards were based on only one loading.

In addition to the design load aspects, the new tables have also been broadened to take into account different de lection requirements depending upon whether plastered or unplastered construction is involvEd. The end result of all these con-siderations is that, in general, allowable spans are increased. It is advisable, there-fore, to become familiar with these tables since by their judicious use a more eco-nomical selection of lumber grades and joist spacings will be possible.

Woll Fronring (p. 84 fo 861

Tables have been added to illustrate permissible stud sizes and spacings for both interior and exterior load-bearing and non-load-bearing walls and partitions. When interim walls support only lirnited attic storage or are non-load-bearing, 2-in. by 3-2-in. studs are permitted 24-2-in. o.c. except for walls having a swing-type door, which are limited to 16-in. stud spacings. Non-load-bearing walls made of 2 by 4 studs on the flat and spaced 16-in. o.c. are permitted regardless of wall length if they do not contain a swing-type door. Tables are also included to provide requirements 4

for lintels over openings in intenior parti-tions as well as outside walls. The latter are identical to the requirements in the 1958 Standards but the former are corn-pletely new.

Roof Frcrning (p.87 to 90)

A new table of nailing requirements has been introduced which represents an important change from the 1958 Stand-ards. Instead of requiring only 3 nails to connect joists to rafters .and joists to joists over partitions, the new table lists the number of nails required which varies with the size of house, slope of the roof and spacing of rafters. In most cases the number of nails .required is greater than in the previous Standards; however, the number of nails may be reduced to the old requirernents if the ridge is supported by 2 by 4 studs to the bearing partition

every 4-ft. (with 2 by 6 ridge board). Similar roof ridge support is mandatory for lower sloped roofs or if the ends of the cei'ling joists do not constitute an ef-fective tie for the ends of the rafters.

If collar ties are used as rafter support to reduce the free span of the rafter, they must be at least 2-in. by 4-in. material. Ties l-in. by 5-in. are no longer per-mitted for this purpose; for lower roof slopes, collar ties of any size will not be considered as effective intermediate sup-port.

Woll Sheothing (p. 92, 931

Wall sheathing is no longer required unless it is necessary for the attachment of cladding or if the cladding requires solid backing such as with stucco or hori-zontal hardboard siding. Wall bracing is also no longer required. When shea,thing such as plywood, gypsum board or fibre-board is used, however, the nailing may be spaced up to 6-in. o. c. along the edge supports and 12-in. o. c. along interme-diate supports. In the case of fibreboard and gypsum board, this represents a sub-stantial reduction in nailing. It should be pointed out that when sheathing is not used, at least two layers of sheathing paper applied vertically must be installed beneath the siding.

Posl ond Beom Conslruction (p. 94 to 96)

A new section has been added to the Standards to cover this type of construc-tion. It is anticipated that future editions of the Standards will contain span tables for decking and beams as well ,as post size and spacings. These were not avail-able in time for the current Housing Standards.

Roofing (p. 98)

A new table has been provided to show the permissible roof slopes for various types of roofing materials. There are a number of detailed changes in the section on roofing and this section should be studied closely to determine the extent of the changes. Some of the more important changes are: Wood shingles are now

per-mitted down to 3/12 roof slope, and both shakes and asbestos cement shingles are now permitted on 4/12 slopes.

P o i n t i n g (p . l l 9 )

The requirements for painting and fin-ishing of both interiors and exteriors have been greatly simplified. The requirements are expressed in more general terms than previously and 'are therefore, ,rnore flex-ible. This simplification does not mean, however, that the formei requirements have been downgraded.

Morlor Mixes (p. 132)

A new table of mortar mixes is now included which provides for various mix proportions depending upon the proposed use of the mortar.

H e o l i n g ( p . 1 3 7 fo 1 4 0 , l5 6 l

This section has boen completely vised 'and here again careful study is re-quired to becorne familiar with the rnany details that differ from the 1958 Housing Standards.

Clearances for heating ducts have been revised considerably and have been sim-plified with sketches. Clearances for ducts are now dependent on the furnace plenum clearances outlined in CSA specifications 8139-1957 and B149-1959 for oil and gas burning equipment, respectively.

To give an example of what the new clearances mean, the standard warm air oil or gas furnace with 250'F. high limit controls must now have a 2-in. clearance from combustible construction in the case of oil or 3-in. in the case of gas (unless approved for lesser clearances) above the furnace plenum and may decrease to I'z-in., 1.8-in. from the furnace plenum. The clearanoe may be reduced to zero where the warm air has made two 90' turns after leaving the furnace heat ex-changing surface. This in effect means that the ctrearance may be reduced to zero in the branch ducts running at right angles from a horizontal supply duct since one right angle turn is rnade when a supply duct leaves the furnace plenu,m, and an-other right angle turn is made at the branch duct. This will also have the effect of no longer requiring /+-in. asbestos around register boxes for this type of furnace.

Return air ducts within 2-ft. of the furnace must be metal and at points where there is a danger that sparks falling through a register might cause a fire (such as at the bottom of the ducts) a metal lining must be provided.

Kilchen Exhousl Fons (p. l57l

Kitchen exhaust fans must be accessible for cleaning through their entire length or miust be equipped with a filter.

This poper is o conlribulion of lhe Division of Building Reseorch,Nolionol Reseorch Council, Conodo, ond is published with the qpprovol of lhe