Subject: Roof reports and MinimumDead Load Question
Date: Sun, 18 Apr 1999 21:41:22 EDT
Apr 18, 1999 6:30 PM
>From the Offices
of Dennis S. Wish, PE
1. To the best of anyones knowledge, is there a minimum roof dead load called
out in the UBC or BOCA codes for assume in residential design?
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?
I have to recommend if a client can change from a Shake roof (with plywood
sheathing) to a lightweight tile. Disregarding the effect of the additional
weight on lateral resistance (typically wind will control in one direction,
seismic in the other) I have inspected the roof trusses which appear to be
very well built and capable (by inspection) of at least a 10 psf top chord
load and a 10 psf ceiling load.
Although this is one of the easier professional opinions for me to make, a
recent post had me questioning if there is a minimum required dead load to
use as there appears to be if a Compo roof is used (3 layers).
Dennis S. Wish, PE
Structural Engineering Consultant