# Spray foam over studs on attic wall



## akjose (Jan 1, 2013)

See picture. I have vaulted ceilings with two high verticals walls that extend to the ceiling on either side of the vaulting. Both are attic walls. I have only seen 1 side as only one side has an access panel. As far as i can recall it has R-38 insulation on those high walls, but cant be attached all that well. The reason I was thinking about it is because we have heating cooling problems (undersized unit).

I got to thinking today that those walls may not be insulated very well. I couldn't remember and it is a pain to get up there so until I can get up there this weekend to take a peek, I was browsing through some photos of when it was being built. Anyway, i came across the attached picture which shows the 9' wall then the triangle wall above it connecting to the truss above (doesn't actually connect although I do have a truss lift crack issue in the peak...another topic). 

So the topic of the post...If I were to spray foam those walls from the attic side, could I just spray over the studs since they are laid on their face? I could do 5 inches have 3.5 over the studs...or would it not work as the foam wouldn't be able to grab onto anything except foam? I could also do 2" and reapply the insulation after foaming (flash and batt).

I will take more pics this weekend when i get up there.


----------



## Windows on Wash (Aug 30, 2011)

Take more pictures when you get up there. 

Spraying over the studs, depending on the application is a great tool to combat thermal bridging.


----------



## Gary in WA (Mar 11, 2009)

I almost hate to bring up anything else wrong to you- given your track record dealing with HVAC system/local idiots.... interesting read. 

The crack in drywall at the peak and possibly along that pictured angle wall on right side- where the framers cut a corner and ripped all the studs from full width to 1/2 width 2x4 making them easy to flex in the middle- and installed them rather than 2x4 on edge so the insulation batt would fit without air pockets for air flow there to de-rate the R-value, no wonder it's cold on that wall. Plus fibrous (faced FG) is open to the attic side without foam board or even housewrap to stop wind washing... studs may bow all over with the SPF unless you nail/screw a horizontal backer 2x about 9' long, mid-height of corner studs. If that ceiling backer 2x is nailed to any truss/shame on them, trusses have to lift- effectively tying wall/truss (ceiling) asking for a gap in drywall at that joint; https://buildingscience.com/documents/insights/bsi-023-wood-is-good-but-strange

Left upper wall studs are turned on the flat... wrong, for the insulators; Pages 43-49/73; https://buildingscience.com/sites/default/files/2010-03-10_When_R-Value_Doesn%20t_Measure_Up.pdf

Gary
PS. Cut an access hole on other side if local Code requires it... *eg; *http://www.iccsafe.org/wp-content/uploads/bcac/IRC-R807.pdf


----------



## akjose (Jan 1, 2013)

I think it must be the picture angle that makes it looks like they are ripped. I am pretty sure they are full width just put on face. Noted on the attic access on other end of house, it is accessible from this side but you have to crawl through 24' of trusses. 

Another more economical option that just hit me is to lay rigid foam 1.5" between framing members then spray foam over the entire thing sealing it all up. 

Here is finished interior:










Sent from my iPhone using Tapatalk


----------



## Gary in WA (Mar 11, 2009)

Or my old tired eyes... lol. FB between the flat studs and then SPF would work best, IMHO, even with the drywall (normally) moving a little under the wood studs that move with the attic humidity- you would be safe. Reword that- the wood moves, not the drywall.

I wish the framer/super./general contractor would get smarter and stop framing walls with studs flat rather than on edge, like normal. The insulator sure doesn't like to Micky M the batts up there because of the extra 2" of stud width and batts cut at 15" wide to hang by compression fit at the sides-- lost that now. Your batt may be folded in toward the attic (esp. if faced) because wider, I doubt extra was cut off sides to fit and now with only 1.5" deep studs rather than 9.5" deep studs to get closer to rated R-value; http://www2.owenscorning.com/litera...ul Compressed R-Value Chart Tech Bulletin.pdf

Except you also have backside open to attic, not a six sided box for rated value so lose to wind in couple of top inches.... if attic is ventilated. AND R-30 is only at 1/2 pound (LOW) density- you lose again; http://www.diychatroom.com/f98/biggest-loser-fiberglass-insulation-90438/ I would guess you are at about R-8-14 now. Rant on FG done, moving on....

That drywall joint crack is the ceiling attached to upward moving truss, wall staying put as the link shows.

May need an ignition barrier on foam, check locally; http://www.icc-es.org/News/Articles/AY126ThermalBarriersSPF2011-51811.pdf

Gary


----------



## Gary in WA (Mar 11, 2009)

I am not a HVAC expert.... in your quest to get more heat to the basement, would changing the flex ducting to solid metal pipe give you better air-flow, hence more BTU's available without that added resistance because of the varying compression in basement picture \; http://www.mmmfg.com/pdfs/060601_CC-KW_DuctTechPaper.pdf OR, maybe it wouldn't help much.

Gary


----------



## akjose (Jan 1, 2013)

Gary in WA said:


> I am not a HVAC expert.... in your quest to get more heat to the basement, would changing the flex ducting to solid metal pipe give you better air-flow, hence more BTU's available without that added resistance because of the varying compression in basement picture \; http://www.mmmfg.com/pdfs/060601_CC-KW_DuctTechPaper.pdf OR, maybe it wouldn't help much.
> 
> Gary


I'm actually trying to get more heat and cool to the main floor. It is quite imbarrasing when you have people over for your daughters birthday and you can't maintain a 72 degree set point. It becomes 78 or 79. I would really like to zone the branch ducts off so i can shut the basement dampers off mostly once finished to force heat to main floor. 

Just came down from the attic. On the wall is only r-19 (faced) ran horizontally the length of the wall. On the left recessed area the stud wall is correct but with 2x4 and again with r19( it does at least extend up past slanted part in this area and overlaps with the r-30 ceiling batt). 

The ceiling is r-30 which I knew with several inches of blown in overtop. Of course, everywhere I step it is now only r30 or less. 

The nailer does not seem to be attached to the truss. It is a 1x6 nailer. Not sure how else that wall would be secured other than both ends. Did not see any nails through nailer to or from the truss. 

I wish I would have caught this during the build. I feel like all I have done since I have moved in is play redo. 

What is a good flexible paintable caulk or silicon to use on that crack from the back side.?

The crack is letting a lot of heat out and I am sure heat back in during summer months. The right side of peak is starting to crack too and pulling tape with it but it hasn't cracked the tape yet. 

I could definitely lay some rigid foam in between and spray over to get the achieved r value.


----------



## akjose (Jan 1, 2013)

More pics


----------



## akjose (Jan 1, 2013)

i dont think there was ever any tape over that opening. Seems the truss was used a nailer on that side, the 1x6 nailer was for the other side. 

The one pic showing the light through the crack, the peak is behind the stud on the left. I think i could get the corner of the drywall released from the truss but would later have the nail pop when the truss settled in the summer.

last pic here, the corner with all the blown in is right where the crack is. Lots of heat coming out. 

Also, I think i would need an ignition barrier depending on what was used for foam product. Still rolling ideas around so let me know what you think.

So far I am thinking (instead of spray foaming):
1.5" XPS foam board in cavities to bring up to level of studs (corners of all cavities caulked or sprayed)
2" XPS foam board horizontally over the stud/xps layer (DWOW products can be used without ignition barrier applied, i think)
I could then put the R-19 batts back over and that would be an ~R-36.5 and at least much more thermally solid and almost doubling or tripling what is actually there now. Could also use Roxul since it is more solid or even another layer of 2" XPS (but that only yields 27.5 not counting the R-19).


----------



## Gary in WA (Mar 11, 2009)

"What is a good flexible paintable caulk or silicon to use on that crack from the back side.?"------------ problem is the gap will change with the humidity. Add some backer rod and sealant; pp 35; https://books.google.com/books?id=XHAyTXye2oMC&pg=PA25&lpg=PA25&dq=capillary+break&source=bl&ots=C_mlI39VL5&sig=JRg-1wVMwEVRrQFiQdX0JxBNa68&hl=en&ei=VMPHS5_pGIyosgPL0eSXCw&sa=X&oi=book_result&ct=result&resnum=8&ved=0CB0Q6AEwBzgK#v=onepage&q=capillary%20break&f=false

I like your last idea because *mineral fiber is the ignition barrier* you need *over *the FB if attic is not used for storage, check local AHJ. Roxul is way better at stopping/slowing air movement, use that on its side after other. http://www.icc-es.org/News/Articles/AY126ThermalBarriersSPF2011-51811.pdf

Solid wood (Doug. Fir) has an R-value of 1.25 per inch, not much and add the gaps from the insulation installer....., this home builder is still in business- because the insulator is so inexpensive. Summertime the truss will come back down... to close the gap, don't use a thick backer. After you're done, rent a FLIR camera to check it--- and other areas as well. You could also just tape over the crack from attic side which will fold (add a strip as wide as the crack in the middle- so other doesn't stick) and open with RH changes, paint the backer rod white to match... eh. 

Gary
PS. check basement for subfloor air sealed- required per code or it feeds the attic... just a thought.


----------



## akjose (Jan 1, 2013)

I was trying to find my flir at work but couldn't. I'm going to buy the iPhone attachment before I fix this issue to show the difference it makes. 

The gap does close in summer. 100% Looks like nothing ever happened. As soon as we kick our heat on for the season it starts opening up. 

Not sure what you mean about the attic. There is electrical that drops from the attic to the main floor walls for outlets. Only thing entering the wall assembly from below is a water line for fridge. 


Sent from my iPhone using Tapatalk


----------



## Gary in WA (Mar 11, 2009)

I was thinking along the terms that the insulator didn't do a good job, but he did the best he could with the studs turned wrong way. That you should check all the wiring/plumbing holes in the basement because most of the time those lead to the attic- "stack effect"; http://www.wag-aic.org/1999/WAG_99_baker.pdf

Post the results when you get them for us! Thanks!

Gary


----------



## akjose (Jan 1, 2013)

I think i may add an attic door behind this picture. Does anyone know of any premade insulated doors. It could either swing to the side or swing up with struts. 



akjose said:


>


----------



## Gary in WA (Mar 11, 2009)

Bad idea if firemen ever need access to stop attic fire and can't find it. Usually in hallway ceiling, move a smoke detector or the light and trim one out there. HO Insurance may not pay a claim if hidden rather than meeting building/fire safety code. Oops, forgot you have the other access... forget I was here...

Gary


----------



## akjose (Jan 1, 2013)

I ended up taking the door off the closet the current scuttle is located in. Made it much easier to get access. My better half wont let me sink any money into it right now so I am trying to find an IR gun without buying one for the time being. Then I can show her the pretty colors. 

I did fix the crack with some backer rod and caulk. Matched it up pretty good and I will have to take a picture. 

Off topic for insulation: I have one wall return that is low. I am thinking it would be worth it to make it a double return in that wall cavity. shut off low in cooling season and shut off high when in heating season. I could also do this in all the rooms as they are all low wall returns (not toe-kicks but about 9 inches up.


----------



## akjose (Jan 1, 2013)

Picked up this sweet deal a week ago. It was on sale for $305 but marked down to $99 special buy. Only had one in stock. 










Sent from my iPhone using Tapatalk


----------

