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Re: Completly shearing a building (also

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Tom Liberty wrote:

>>UBC Section 2506.4 requires minimum two layers of Grade D paper for wood
sheathing  when stucco is applied. This would be indicative of the lack of
weather protection of the wood sheathing.<<

True, but is Grade D paper adequate weather proofing?  UBC Standard 14-1 
(1997 UBC Standards) indicates that the water penetration resistance of Grade 
D kraft paper is only required to be 1/6 hour (10 minutes).  Grade A paper 
has 24 hours, Grade B paper has 16 hours, Grade C paper has 8 hours as the 
minimum times before water penetrates the paper.

A number of years ago, a code change proposal was submitted by some 
California building official to change the requirement to Grade B paper.  The 
staff analysis, IIRC, was that the vapor permeability of Grade B was not 
comparable to Grade D, and the proposed change was rejected.

Masonry also isn't a "weather resistant" material.  Interior unfinished 
masonry is common in this area, particularly when slump block is used.  I 
have seen water quickly penetrate masonry walls when water from a hose is 
permitted to flow (not squirted under pressure) on the wall.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona