headers in gable end walls? what do you engineers think?
marson
load). the specs call for no headers in non-load bearing exterior
walls (gable walls). i'm not entirely trusting this architect--he's no
structural whiz. my question--is a wall supporting the rake overhang
really non structural? it's a two story house on a walkout basement.
it has 24" overhangs, framed with lookouts which bear on a drop chord
gable truss which sits on the so called non-bearing wall. what do you
guys think about no headers in such a wall? the headers are left out
to reduce thermal bridging.
Chas Hurst
"marson" <brian...@gmail.com> wrote in message
news:1163898418.3...@h54g2000cwb.googlegroups.com...
Sounds good to me. The gable end isn't holding up much, if any, of the roof.
The trusses are supporting the overhang.
Some inspectors in my area want to see a header over every opening in the
wall.
tj
First, I live in South Florida and snow load is not a issue but rather
designs are based on high wind designs. As a result, most building
dept. down here reject framing plans that call for gable end trusses.
Secondly, the end wall on gable structure are structional load
carrying walls! Just look at your truss engineering for the drop gable
end truss. The truss engineering will show the PLF for the bottom
chord for continues bottom chord bearing. Granted, the gravity loads
will be much lower than the in-field trusses since the in-field trusses
will have two points of bearing while the gable end will have continues
bearing on the top plate of the gable wall.
Consider ballom framing the gable end wall and eliminate the gable
trusses.
marson
so explain the advantage of balloon framing a gable wall in my case?
we don't have wind loads to speak of. and even if you have to add t
bracing, you're way ahead on labor with a truss.
Bob Morrison
You need some sort of structural member (header) to transfer wind loads
horizontally to the sides of the opening. This is especially true if the
opening is very large (let us say over 3 feet).
Here in the Pacific NW it is common to install headers in gable end walls,
but they are often 4x members in a 2x6 wall. 2" of rigid insulation is
glued to the inside face and GWB is applied over with longer screws.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com
marson
I was planning to use two two by fours oriented "flatwise" in lieu of a
insulated tji header. And if lateral loads are the issue, then I'm
thinking I don't need to worry about the walkout walls where the floor
plywood above is tied to the foundation.
HerHusband
>> snow load). the specs call for no headers in non-load bearing
>> exterior walls (gable walls). i'm not entirely trusting this
>> architect--he's no structural whiz. my question--is a wall
>> supporting the rake overhang really non structural? it's a two story
>> house on a walkout basement. it has 24" overhangs, framed with
>> lookouts which bear on a drop chord gable truss which sits on the so
>> called non-bearing wall. what do you guys think about no headers in
>> such a wall? the headers are left out to reduce thermal bridging.
> You need some sort of structural member (header) to transfer wind
> loads horizontally to the sides of the opening. This is especially
> true if the opening is very large (let us say over 3 feet).
> Here in the Pacific NW it is common to install headers in gable end
> walls, but they are often 4x members in a 2x6 wall. 2" of rigid
> insulation is glued to the inside face and GWB is applied over with
> longer screws.
I live in the Pacific NW too, and I used two 2x10 headers over every door
and window opening (2x6 walls), even on the gable ends. One aligned with
the exterior, one aligned with the interior, and then filled the 2-1/2"
space in between with insulation. I added a strip of 1/2" plywood along the
bottom edge to provide a continuous surface for installing the window and
trim. This offered better insulation than a solid or built-up beam,
eliminated the need for cripple studs over the openings, and provided
plenty of support for each opening. It also gave me plenty of nailing area
for the exterior sheathing and interior wall coverings. Several of the
headers were cut-offs from longer floor joists, so there was also very
little additional cost.
Question for you Bob... If insulation were a big concern, could you rip
2x6's down to 4-1/2" then build a box beam with a layer of 1/2" plywood on
each side, filling the center with rigid insulation? Especially for a gable
end, it seems like it would offer plenty of support for the average window
opening.
Anthony
DT
>I live in the Pacific NW too, and I used two 2x10 headers over every door
>and window opening (2x6 walls), even on the gable ends. One aligned with
>the exterior, one aligned with the interior, and then filled the 2-1/2"
>space in between with insulation.
That's the way I like to build headers also. In 2x4 construction I use a piece
of 1/2" Tuff-R between the wood to pick up an extra R 3 on each header.
--
Dennis
Bob Morrison
> I was planning to use two two by fours oriented "flatwise" in lieu of a
> insulated tji header. And if lateral loads are the issue, then I'm
> thinking I don't need to worry about the walkout walls where the floor
> plywood above is tied to the foundation.
>
(2) 2x4 flatwise perform OK for horizontal loads as a structural member.
I sometimes specify 4x6 flat for small openings to get better vertical
performance as well.
You could also form an "L" with (2) 2x and get reasonable performance over
small (3-foot) openings.
Bob Morrison
> Question for you Bob... If insulation were a big concern, could you rip
> 2x6's down to 4-1/2" then build a box beam with a layer of 1/2" plywood on
> each side, filling the center with rigid insulation? Especially for a gable
> end, it seems like it would offer plenty of support for the average window
> opening.
>
Seems like a lot of work. That's why I typically go for 4x headers with
2" rigid glued on the inside face. This offers plenty of support for GWB
if you use long screws. This will require longer finish nails if you are
trimming out the opening in wood, but most of these houses use GWB for the
top and sides of the opening and only have wood on the sills, where of
course you have a 2x6.
BTW, I agree with you idea of using a taller header in order to eliminated
short blocks between the header and the double top plate. The wall frames
faster that way.
marson
reduce thermal bridging. Wood is about R 1 per inch, so less wood
and more insulation is the goal.
Dick Russell
You originally said that you are framing a "superinsulated house" in
northern Minnesota, yet I get the impression your wall frame is just
2x6 studs with some reduction in thermal bridging in plates, headers,
etc. I am curious as to what your whole wall looks like and what
insulation you will be putting in the cavity, plus what total wall R
value you are shooting for. If you have 2x6s 16" oc, that's a lot of
thermal bridging.
marson
For the most part, it is a 9" double 2x4 wall with dense pack
cellulose. The outer wall is the load bearing wall. We are shooting
for R-36. This was not my idea, and I would have steered the client
toward a 2x6 wall, spray foam, and 1" foam on the outside to address
thermal bridging, but I got the project too late in the process to give
my two cents worth. Eliminating headers in the gable end walls was a
spec I was given on the plans. The architect specializes in energy
efficient houses. (in reality, I realize that "thermal bridging" isn't
exactly the issue with headers in this case--we want to eliminate
unnecessary wood where possible.) I posted the question because the I
don't necessarily trust the architects structural judgement--after all,
noone will call HIM if the sheetrock cracks!
HerHusband
>> rip 2x6's down to 4-1/2" then build a box beam with a layer of 1/2"
>> plywood on each side, filling the center with rigid insulation?
>> Especially for a gable end, it seems like it would offer plenty of
>> support for the average window opening.
> Seems like a lot of work.
Agreed, but if you were trying to pack as much insulation as possible in a
2x6 wall header, it seemed like a possible option. Of course, you'd still
have the thermal bridging of the studs themselves, but that's a different
case... :)
> That's why I typically go for 4x headers with 2"
> rigid glued on the inside face.
Is there some reason you don't use separate 2x material on each face and
put the insulation in between? You don't need longer screws for the
drywall, and it offers better support for things like curtain rods.
I suppose it offers slightly less resistance to horizontal wind loads, but
I would think the double 2x6 top plate would take care of that?
Anthony
marson
HerHusband wrote:
> >> Question for you Bob... If insulation were a big concern, could you
> >> rip 2x6's down to 4-1/2" then build a box beam with a layer of 1/2"
> >> plywood on each side, filling the center with rigid insulation?
> >> Especially for a gable end, it seems like it would offer plenty of
> >> support for the average window opening.
>
> > Seems like a lot of work.
>
> Agreed, but if you were trying to pack as much insulation as possible in a
> 2x6 wall header, it seemed like a possible option. Of course, you'd still
> have the thermal bridging of the studs themselves, but that's a different
> case... :)
>
> > That's why I typically go for 4x headers with 2"
> > rigid glued on the inside face.
>
> Is there some reason you don't use separate 2x material on each face and
> put the insulation in between? You don't need longer screws for the
> drywall, and it offers better support for things like curtain rods.
> I suppose it offers slightly less resistance to horizontal wind loads, but
> I would think the double 2x6 top plate would take care of that?
>
> Anthony
well, where we do need a header, we use pre insulated tji headers
(http://www.swi-joist.com/p_04.htm). might not be available in your
area. but 4x material is not stocked in yards where I live.
Brady
How many plates can you have total in a wall. How many inches of compression
can you have?
--
for full context, visit https://www.homeownershub.com/construction/headers-in-gable-end-walls-what-do-you-engineers-think-4027-.htm