Design Assumptions for Tables 9.23.10.1.-A to 9.23.10.1.-D:
1.
Roof dead load is 0.5 kPa (asphalt shingle roof) as per rafter and lintel tables in the Building Code.
2.
Specified roof snow load is the factored load incorporating rain load as per the rafter, header and lintel spans in the Building Code.
3.
Wind loads are based on wind loads in the 2006 Building Code and the 2005 edition of the NBC as adopted in the Engineering Guide for Wood Frame Construction published by the Canadian Wood Council a.
Basic wind pressure is the 1 in 50 year pressure found in Table 1.2 of MMAH Supplementary Standard SB-1 b.
Ce = 0.7 as per Sentence [b-4.1.7.1.#^5hplca|4.1.7.1.(5)] in the Building Code c.
Cp Cg = –2.1 for ultimate limit state for wind acting alone d.
Cp Cg = –1.75 for the serviceability limit state e.
Cp Cg = 1.5 for wind acting in combination with gravity loads f. Cpi varied from –0.45 to 0.3 as per User’s Guide - NBC 2005, Structural Commentaries (Part 4 of Division B).
Where external wind was a pressure (wind acting in combination with axial loads) the internal wind suction coefficient of –0.45 was used. Where external wind was suction (wind acting alone) the internal wind pressure coefficient of 0.3 was used. g. Cgi = 2.0 as per Sentence [b-4.1.7.1.#^6hplca|4.1.7.1.(6)] in the 2006 Building Code. h. The importance factors used to calculate wind loads were 1.0 at the ultimate limit state and 0.75 at the serviceability limit state as per Table 4.1.7.1. in the 2006 Building Code.
4.
Ultimate Limit State loads cases were in accordance with Table 4.1.3.2. in the 2006 Building Code. a.
1.
4 axial dead load b.
1.
25 axial dead load + 1.5 axial snow load c.
1.
25 axial dead load + 1.5 axial snow load + 0.4 lateral wind load d.
1.
25 axial dead load + 0.5 axial snow load + 1.4 lateral wind load e.
1.
4 lateral wind load
5.
Serviceability Limits States, based on the Engineering Guide for Wood Frame Construction, were calculated using specified lateral wind loads, and included: a.
Deflection limit of stud length/180 for walls with siding, and b.
Deflection limit of stud length/360 for walls with brick cladding.
6.
Stud resistance was calculated as per CSA O86 and adopted for the Engineering Guide for Wood Frame Construction a.
The system factors used were Case 2 load-sharing for bending moment resistance and Case 1 for compression resistance parallel to grain. b.
A load duration factor of 1.25 was used where lateral wind acted alone or in combination with axial loads.
7.
Fastening requirements are based on the short-term nail resistance values given in CSA O86-01.