Need thin insulation for masonary wall.
Hi,
I have a 1950 house with double masonary exterior walls. I am installing wainscott wood panelling in my living room and have removed the bottom 3′ of rock board and plaster around the whole room. There are vertical 3/4″ strapping strips 16″ on center on the masonary walls. There is no insulation on these walls with the exception of layer of a tar paper type barrier between the strapping and the masonary.
Before I put the wood wainscott on, I would like to add some insulation between the strapping. As I mentioned, I only have 3/4″ inches to work with, so my options are limited. I originally considered the foil coated bubble wrap insulation, but after reading the reviews here, I now not so sure of that…it’s also damn expensive.
Can anyone please offer any suggestions?
Thanks very much in advance.
Bill
(See attached photo)
Replies
Good insulating R value in 3/4" (and add to that not too expensive).
There is a material called unobtanium, but it can be hard to find. ;-)
Anyway, here is a comparison chart of your choices:
http://hes.lbl.gov/hes/makingithappen/no_regrets/insulationcomparison.html
Owens Corning pink foam board insulation ("propink" insulating sheathing) comes in 3/4" thickness and says it gives R-4 performance at that thickness.
"Let's get crack-a-lackin" --- Adam Carolla
Try to locate some polyurethane or polyisocyanurate board, a bit more R.
I am surprised I recall this " unobtanium " but I remember having a set of riding glasses that actually had a trade name of "unobtanium". The pun is still funny though
I think back in the 60's is when I first heard the term. I think it was attributed to Mark Donohue (of Penske Racing) saying that his Porsche race car was made of that "material."
1/2" foil-faced polyiso board will give a decent R-value in a 3/4" space. I like to cut it a little undersized and foam all the edges to prevent air movement. Shiny side goes in, toward the dead air space.
Bill
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There are foamboard products for just this situation. They are already aprox. 3/4 by 14-1/2" by 96" and fit nicely between 1x2 firring 16" o.c. The Menards here stocks it. IIRC the stuff i've used is just EPS and is only R-3, but is cheap & easy. Use PL-300 or eq.
Thanks to all who replied. Very informative.Bill
When I wanted to do this they only had 1/2" and 5/8" thick in the precut stuff, and all of it was the crummy styro vs polyiso. Plus I was dealing with some really wonky pre-existing firring, so I bought 4x8 polyiso sheets and cut to fit. Got a squeeeky-tight fit that way -- no glue needed.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
When cutting foamboard, I undersize it some to speed up the process, then spay foam any gaps.The stuff for 16" OC firring that I found was styro (EPS) vs. XPS or polyiso, but it was a full 3/4" IIRC. It does take 3/4" of EPS to equal the R-value of 1/2" polyiso.This is how I like to insulate over cement block or concrete, with 1-1/2" XPS with an R-7.5 rating. The channels for the firring are molded into the 2'x8' sheets so the firring is isolated from the potentially moist masonry. The 3/4" of XPS behind the firring also reduces thermal bridging. I make my own 1x3's out of 3/4" plywood. Same $ and nice and straight.
Curious as to your experience with this material. I'm looking to insulate the kitchen in my 1850s brick rowhouse without loosing all the space I would if I put in stud walls. My main concern is that I'm dealing with soft clay brick, need to hang kitchen cabinets (obviously) and I'm curious if the insulpink+furring strips could take the weight of cabinets on it. I'm doubtful it would, and I'm at a loss how to do this, any ideas?Thanks,
Z
I think cabinets over drywall/inulpink&firring/brick would work fine. I've hung cabinets in ICF houses over drywall and into the plastic mounting clips in EPS over concrete.On our Insulpink projects, the firring strips we used were 1x3's ripped out of 3/4" BC plywood. The firring strips were glued and screwed (with PL300 and tapcons). We apply the PL300 generously to the masonry in dabs, put a 2" rip of 3/4" XPS pressed into a bead of PL300 on floor at the base of the wall.Then run another bead of PL300 on top of the rip and press the first full 2x8' panel into the glue on top of the rip. Keep adding full panels & 1x3's on up the wall (more about the top panel later if you want the details). The extra rip on the bottom of the assembly allows us to use full 1x3's on the bottom of the wall for a baseboard nailer.That is how we insulate a standard masonry wall. Plenty of PL300 and tapcons every 16" on the firring. With soft brick, I might try every 12" and fine tune the pilot hole size for a good grab and don't overdrive and strip it out.For a cabinet wall, we would add a larger 10" rip of an 1-1/2" InsulPink panel as a starter course so that a 1x3 firring strip was centered about 34" off the floor (for attaching base cabinets) and firring strips would land centered at 58 and 82" off the floor for anchoring near the bottom and top of common wall cabinets.Once the PL300 sets up, the panels are firmly attached to the masonry, to the floor, adjacent panels, and to the firring strips. The system is very sturdy and virtually air tight.Also we use PL300 liberally when installing drywall to the XPS and firring. I would hang cabinets on the InsulPink system, as long as it is installed well...no problem.More tips later, if you are still interested.
Try rigid polyisocyanurate with a foil backing(to reflect heat in)...it has about the highest r valueper inch of any easily available insulation
Foil facing as a radiant barrier requires 3/4" or more of air space between the foil and the wall board. Without the air space no benefit is achieved. In this application the foil is wasted.
You sir (or ma'am) are right. Thanks for the correction.
The Polyiso part was good though.
Thankyou. Smartypants!
I certainly understand your desire for some insulation, but I suggest you run the Manual J calculations before and after for any option you are looking at. Then you will know what the actual gain should be, and how much money you might save. I'm thinking that any gain will be pretty small.
Generally, with masonry walls, the best gains are sealing air gaps. If you can, seal around window and door openings.
>>"I'm thinking that any gain will be pretty small.
What do you use as the R value of a masonry wall? I have common brick at, best case, .4 per inch, plus .68 indoor air film plus .17 outdoor air film. Assuming an 8" thick brick wall, that gets me R 4.05
Won't 3/4" foam board at R 4 basically double it?
I agree infiltration is the bigger loss, but doubling the insulation . . . .
People pay huge bucks to get an R 3 versus an R 2 window. This is a whole wall.
"Let's get crack-a-lackin" --- Adam Carolla
Edited 5/9/2006 10:59 pm ET by philarenewal
The heat loss program I used you just input the building construction and it calculates the total heat loss. Do it both ways and you'll have the answer. This has the advantage of taking into account any interactions the changes might have (if you are doing more than one change).How are you doing the whole wall? It looks to me like you are only doing the bottom half or so. Doubling the R-value might or might not make much difference. If you are close to zero to start, then doubling doesn't help much. And if you are at a very high R value to start, doubling might not have any impact. Which is why getting the heat loss before and after, and converting to cost is a better answer.
Regardlesss of the actual total heat loss through the wall, insulation will significantly improve comfort level for those near the wall. This in turn allows the thermostat to be set lower in heating season.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison