Re: post and beam sb house

["John Dittli" <dittli@earthlink.net>]

----- Original Message -----
From: "David J Heritage"

>Is the 100lbs/sq ft just to accommodate snow loads?

Yes

>. Are the 4 foot max spans just along the wall? What kind of clear spans do
>you have on the interior of the house?

The 4 foot 6x12 spans are along the load/roof bearing walls only. I think
the engineer may have been over zealous. We have a 6 ft opening where he
made me stack a 6x8 under the 6x12! Fortunately I had access to 2nd hand
beams!

I assume the clear span you speak of is inside from wall to wall? If so, we
have flat bottom cord, 6:12 top cord, trusses on 2' centers that span 32
feet with no interior support. These trusses cantilever 2 feet on either
side; total truss length is 36 ft. The nice thing about cantilever trusses
is that you can have any size overhang you want without covering up your
windows.


>What kind of insulation did you use for the >ceiling/roof? What R- value do
>you have in the ceiling?

We used salvaged fiberglass batts (I'm not sure I recommend that, very
messy, but felt good to keep it out of the landfill).  We put one layer of
R19 (w/o vapor barrier) against the roof and two R19 batts in the ceiling.
My theory with this was that the roof insulation would keep the attic space
(vented) cooler in summer. We have a 2nd floor that is "nested" in the first
floor roof so rather then insulate against a 120+ degree attic I figured I
would attempt to keep the attic closer to the ambient outside air (90
degrees max.)


> Its interesting that your engineer equated a built up 6x8 to a solid 6x6.
> An old structural design book I have says "A built-up beam thus
> constructed has a strength equal to the sum of the strengths of the
> individual pieces."

I found this puzzling also. But looking at his calcs I see he specifically
states;  "3 2x8 may be substituted for 6x6". Of course 3  1 1/2" boards only
equal 4 1/2" rather than the 5 1/2" of a 6x. However, one would think the 2-
1/2" plywood firring strips would add considerable strength. Sounds like a
good question for the engineeroids on the list.

I hope this helps.

John Dittli

------------------------------------------------------------------------
To unsubscribe from the strawbale list, send email to majordomo@crest.org
with the one of the following messages:
unsubscribe strawbale
or
unsubscribe strawbale-digest
if you are on the digest version of the list.
Please send any other list administration questions to
owner-strawbale@crest.org