Hi Robert,
You might remember I spoke with you about using the modified Larsen Truss
for this house, but we went stick frame since the house is sided with
hardi plank instead of 4/4 shiplap. We ended up framing an exterior 2x4
wall 16 OC and an interior 2x2 (2x4 rips) 16 OC tied into the exterior
wall with two 1/2 ply gussets/spacers. This saved on materials. We used
2x12 top and bottom plates which we found allowed us to frame entire
sections of wall all at once and quite efficiently. We traded speed for
what we felt was a minor thermal break compromise by using 2x12. We
sheathed with 1/2 CDX pine covered with raindrop house wrap with taped
seams. Hardi plank siding (pre-painted) went on top of the sheathing.
Inside we used 5/8 sheet rock with caulked seams, then taped and painted
with AFM safecoat. The walls were filled with dense packed cellulose at 3
pcf prior to sheet rock installation using a heavier lanscape type fabric
stapled tight just to the inside of the studs to minimize bulging. That is
the basic cross section.
Tim Yandow

> A continuous air barrier is more crucial, though in a high-humidty
> environment like a shower a vapor barrier is wise as well. The 6 mil poly
> can serve both functions as long as there are no unsealed penetrations and
> the poly is sealed at edges and seams.
>  
> Laticrete 9235 is a water barrier but not a vapor barrier (3 perms). You
> might use it on the shower base (if that is tile), but I would use a vapor
> barrier on the walls and make sure there is a quiet, efficient exhaust fan
> operated by a short-term timer.
>  
> What kind of double wall system are you using? Can you share a
> cross-section?
>  
> - Robert
>
> --- On Thu, 12/18/08, Tim Yandow <[log in to unmask]> wrote:
>
>>I am interested to know if anyone has an opinion about or experience with
> the following situation:
> I am currently constructing a 2000 sq ft double wall, dense pack cellulose
> house. Due to a number of factors, an upstairs shower stall, 4' X 4'
> ended
> up in an outside corner of the house (north west corner). I know this is
> not a great spot for it, but there it is. The tiler would like me to place
> a vapor barrier over the framing before the hardy backer and tile go on.
> There is 12 inches of cellulose in the walls with a thermal break (2- 2x4
> walls) behind the shower. This I presume is to keep moisture from the
> shower away from the insulation. I am wondering if this is a good idea
> given the porous nature of tile and hardy backer. Any input? Thanks.
> Tim Yandow
>
>
>
> I am not sure what makes the most sense here
>