Subject: Re: Roof reports and MinimumDead Load Question
Date: Wed, 21 Apr 1999 02:35:51 EDT
In a message dated 4/18/99 7:45:57 PM Mountain Daylight Time,
<< 1. To the best of anyones knowledge, is there a minimum roof dead load
out in the UBC or BOCA codes for assume in residential design? >>
UBC 1997 Chapter 16 section 1602 defines dead load as the weight of
all materials and fixed equipment incorporated into the building or other
structure. To my knowledge there in no minimum called out.
<<2. Is there a minimum dead load to assume for the design of plated roof
trusses (Gang-nail type trusses) when used for residential design (like 10
psf top chord and 10 psf bottom chord).
<<3. What weight is assumed for Cedar Shake (Split shake and not shingle)? Is
this weight assumed to be dry weight or the weight of the shake when wet?
ASCE Minimum design loads for Building and Other Structures ASCE 7-88 gives a
table of mimimum design loads (C1) lists wood shingles @ 3 psf.
Check the truses for grade marking on top and bottom cords and web members.
These grade changes allow the manufacture to reduce cost and increase
strength. The code allows 3 layers of shingles before they have to be
stripped. Be carefull about this recently I was on a job site where there
were 6 layers of asphalt shingles on covered while tying in and addition.
The lower layers of shingles were covered by a metal drip edge.
I hope this helps
Jay L. Crawford, P.E.