# Insulation between furring strips



## Scuba_Dave (Jan 16, 2009)

If you want proper insulation install at least 2" rigid for R10


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## RMCarner (Mar 23, 2009)

Scuba_Dave said:


> If you want proper insulation install at least 2" rigid for R10


I was hoping not to push the space out that far... This is a small efficiency apartment. 2" rigid would imply that I really almost need to frame out the wall...

Dick


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## Ron6519 (Mar 28, 2007)

Remove the remaining plaster and put batts in the stud cavities. Putting furring strips over a brown coat makes no sense, especially if you also want to insulate the space.
Ron


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## RMCarner (Mar 23, 2009)

Ron6519 said:


> Remove the remaining plaster and put batts in the stud cavities. Putting furring strips over a brown coat makes no sense, especially if you also want to insulate the space.
> Ron


Wish there were stud cavities..:no: What I'm looking at goes back to maybe the 1880's. I could be wrong, but I believe this outside wall is comprised of two layers of brick, lath, and three layers of plaster. It appears that someone attempted to reapply a thin coat in the 1920's or so, but I'm not absolutely sure about that. There isn't a stud in this entire building facing the outside.

This is a rental unit. I need to find a solution that isn't necessarily the best but gets me in and out in a reasonable amount of time and price wise. I decided to go with 5/4 furring strips and 1" Tuff-R that I got at the Box Store. For what it's worth, the R value of this stuff is between 5-6. Better than nothing which is what is there now. Plus, I deal with the cosmetic issues by covering the wall with drywall. Comments?

Dick


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## RMCarner (Mar 23, 2009)

RMCarner said:


> Wish there were stud cavities..:no: What I'm looking at goes back to maybe the 1880's. I could be wrong, but I believe this outside wall is comprised of two layers of brick, lath, and three layers of plaster. It appears that someone attempted to reapply a thin coat in the 1920's or so, but I'm not absolutely sure about that. There isn't a stud in this entire building facing the outside.


Correction: I know now that there is no lath. Rather what I have are 3 coats - a render layer, a floating layer, and a setting layer. Deterioration is evident all the way down and into the render layer. Fossil fuel was so cheap back then, I guess you could get away without any insulation to speak of. 

Dick


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## Gary in WA (Mar 11, 2009)

R-5 outside sheathing on an empty wall if in Lancaster, PA: http://www.ornl.gov/sci/roofs+walls/insulation/ins_16.html 

The inspector may buy it. If you could leave an air space------- (2) System R-value is the sum of the product R-value plus additional R-value calculated when the aluminum foil surface is installed next to a non-ventilated 3/4" air space (R-value = 2.8). http://www.dow.com/PublishedLiterat...foam/pdfs/noreg/179-07932.pdf&fromPage=GetDoc

Be safe, Gary


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## RMCarner (Mar 23, 2009)

GBR in WA said:


> R-5 outside sheathing on an empty wall if in Lancaster, PA: http://www.ornl.gov/sci/roofs+walls/insulation/ins_16.html


Very useful source. Thanks.



> The inspector may buy it. If you could leave an air space-------


Not following you here. :huh: The plan (not absolutely set in concrete yet..) was to attached the furring strips to the existing plaster then cut the Tuff-R to fit - shiny side toward the outside. Then cover with sheetrock. In the link you provided above I found the following statement:_ "_It is sometimes feasible to install rigid insulation on the outdoor side of masonry sidewalls such as concrete block or poured concrete._However, if that is not an option, you can use rigid insulation boards or batts to insulate the interior of masonry walls. To install boards, wood furring strips should be fastened to the wall first. These strips provide a nailing base for attaching interior finishes over the insulation. Fire safety codes require that a gypsum board finish, at least 1/2 inch thick, be placed over plastic foam insulation. The gypsum board must be attached to the wood furring strips or underlying masonry using nails or screws." _




> (2) System R-value is the sum of the product R-value plus additional R-value calculated when the aluminum foil surface is installed next to a non-ventilated 3/4





> " air space (R-value = 2.8). http://www.dow.com/PublishedLiterat...foam/pdfs/noreg/179-07932.pdf&fromPage=GetDoc


If I get your drift, what you seem to be saying is that I am going to take a hit on the effective R-value if I do not somehow include an airspace. How do I do that without at the same time losing touch with my original goal, which was to minimize space lose? Lancaster has more old buildings per capita than any other city in the US. I know of several contractors that use this technique if they are constrained by a budgetary process. I dunno, I'm all ears for other ideas, but I am also constrained that way as well. Thanks.

Dick


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## Gary in WA (Mar 11, 2009)

What I meant was, check with your local building department for the required R-value. If they will accept what you have planned, as the foil is vapor impermeable (0.003): http://www.ornl.gov/sci/roofs+walls/staff/papers/143.pdf http://fire.nist.gov/bfrlpubs/build96/PDF/b96086.pdf


Be safe, Gary


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## RMCarner (Mar 23, 2009)

GBR in WA said:


> What I meant was, check with your local building department for the required R-value. If they will accept what you have planned, as the foil is vapor impermeable (0.003): http://www.ornl.gov/sci/roofs+walls/staff/papers/143.pdf http://fire.nist.gov/bfrlpubs/build96/PDF/b96086.pdf


Okay, Gary Thanks.
Dick


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