Insulating two walls of a bedroom-- spray foam too expensive!
#21
  Re: RE: Insulating two walls of a bedroom-- spray foam too expensive! by daddo (You're not going to ...)
(09-21-2018, 05:44 PM)daddo Wrote: You're not going to notice any if much difference between r13 and r20 in the walls. You will, however notice a difference stopping the infiltration. Fix the air leaks and the batting would do fine.  Well sealed walls are are most important than the r factor. The attic and windows are a different story.  Of course the foam will seal the walls, but I personally wouldn't want gassing foam in my walls and not being able to run/replaced a wire or pipe.. .....
The tighter cellulose gets, the more it stops infiltration and the r factor goes up- it does settle. Just my observations.

You might look for another reason you notice no or little difference.


^^^  The most heat loss is thru windows and doors, then the ceiling, then the walls, and the floors the least.  Infiltration, of course, is even worse but a separate issue and one that spray foam insulation deals with w/o extra effort.  That said, I would use fiberglass or rockwool in the walls and then install a vapor barrier over it, under the drywall (if you live in a cold climate; I think it's the other way around if you live somewhere warm).  

John
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#22
  Re: RE: Insulating two walls of a bedroom-- spray foam too expensive! by daddo (You're not going to ...)
(09-21-2018, 05:44 PM)daddo Wrote: You're not going to notice any if much difference between r13 and r20 in the walls. You will, however notice a difference stopping the infiltration. Fix the air leaks and the batting would do fine.  Well sealed walls are are most important than the r factor. The attic and windows are a different story.  Of course the foam will seal the walls, but I personally wouldn't want gassing foam in my walls and not being able to run/replaced a wire or pipe.. .....
The tighter cellulose gets, the more it stops infiltration and the r factor goes up- it does settle. Just my observations.

You might look for another reason you notice no or little difference.
I completely agree. If there is any air flow through the insulation then the R-value goes right out the window, so to speak. Also on the ceiling you need to stop air infiltration, but do not stop moisture vapor; let that go out your ridge vent. Also, no double vapor barriers (i.e. kraft faced and poly). That is where the greatest difference in temperature will occur and you will get condensation and mold.
Sign at N.E. Vocational School Cabinetmaking Shop 1976, "Free knowledge given daily... Bring your own container"
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#23
  Re: Insulating two walls of a bedroom-- spray foam too expensive! by Cdshakes (So I'm about to rip ...)
How is attic insulation and are your windows double-paned?

We had cellulose blown into the walls.  Helps a bit, but the two above made the bigger difference.

Matt
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#24
  Re: Insulating two walls of a bedroom-- spray foam too expensive! by Cdshakes (So I'm about to rip ...)
Since it's a cape-cod, about half of it is exposed to the unconditioned attic space above (2nd floor has short walls on the side).
I put down pieces of r19 in between each joist, and then laid some foam board perpendicular to the joists to try and keep the part of the ceiling insulated.  Under the part of the 2nd floor that has the conditioned space above it is empty.

Colin
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#25
  Re: Insulating two walls of a bedroom-- spray foam too expensive! by Cdshakes (So I'm about to rip ...)
Iffin it were up to me... I'd staple up R-13 and be done with it. Make certain the ceiling is R-30+. Not much heat is lost through the walls as heat rises. Not only that, spray foam is a pita if you (or anyone) ever need do anything else with the walls.
 
"My mortgage self-identifies as a student loan."
... Kizar Sozay


Neil Summers Home Inspections
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#26
  Re: Insulating two walls of a bedroom-- spray foam too expensive! by Cdshakes (So I'm about to rip ...)
I would get a DIY kit and skim coat the walls for the air seal and then put up bat insulation - get the benefit of a sealed room and the cost effectiveness of batt insulation. OR if budget allows in order to make it a big enough job, have a contractor come in and spray the walls and also go into the attic and skim coat the ceiling from the top. We did this when we had them spray our basement (daylight windows on 2/3 of the walls), they also filled in all the rim-joist and it made a HUGE difference in only a 5yr old house.
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#27
  Re: RE: Insulating two walls of a bedroom-- spray foam too expensive! by vernonator (I would get a DIY ki...)
(09-25-2018, 10:55 AM)vernonator Wrote: I would get a DIY kit and skim coat the walls for the air seal and then put up bat insulation - get the benefit of a sealed room and the cost effectiveness of batt insulation. OR if budget allows in order to make it a big enough job, have a contractor come in and spray the walls and also go into the attic and skim coat the ceiling from the top. We did this when we had them spray our basement (daylight windows on 2/3 of the walls), they also filled in all the rim-joist and it made a HUGE difference in only a 5yr old house.

when you say skim coat, do you mean a thin coat of spray foam?
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#28
  Re: RE: Insulating two walls of a bedroom-- spray foam too expensive! by daddo (You're not going to ...)
(09-21-2018, 05:44 PM)daddo Wrote: You're not going to notice any if much difference between r13 and r20 in the walls. You will, however notice a difference stopping the infiltration. Fix the air leaks and the batting would do fine.  Well sealed walls are are most important than the r factor. The attic and windows are a different story.  Of course the foam will seal the walls, but I personally wouldn't want gassing foam in my walls and not being able to run/replaced a wire or pipe.. .....
The tighter cellulose gets, the more it stops infiltration and the r factor goes up- it does settle. Just my observations.

You might look for another reason you notice no or little difference.

I figure I will use great stuff around the window rough openings.  Do you think putting a bead in each stud cavity would be helpful, or what way do you think would be best to seal it up so that r13 batting is sufficient?

Colin
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#29
  Re: Insulating two walls of a bedroom-- spray foam too expensive! by Cdshakes (So I'm about to rip ...)
Rip out drywall.
Add 2 x2's to the studs and put in 6" of insulation?
I long for the days when Coke was a soft drink, and Black and Decker was a quality tool.
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#30
  Re: RE: Insulating two walls of a bedroom-- spray foam too expensive! by Cdshakes ([quote='daddo' pid='...)
(09-25-2018, 02:50 PM)Cdshakes Wrote: I figure I will use great stuff around the window rough openings.  

Colin

I wouldn't do that. In essence, you are gluing in the windows. That will make a miserable chore if they ever need replacing... and they will. If the foam expands, you could distort the window frame, reneering it useless. I know people do this but it really doesn't buy you any measurable advantage and can cause a great disadvantage. No need to over-think this. The products used in the industry are used for a reason. They work. They're easy and they can be removed if needed. If the windows are framed properly, there's just a small gap between the window and the framing. Either stuff some insulation in any voids or tuck in some foam backer rod. That's what it's for.
Before you use any foam products, make sure they have proper fire ratings.
 
"My mortgage self-identifies as a student loan."
... Kizar Sozay


Neil Summers Home Inspections
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