# insulating existing wall under wainscoting? and inside closets



## DarrenLevine (Aug 3, 2016)

I'm working on our bedroom to be, and it needs some more insulation. It has wainscoting going 4' up the entire perimeter of the room, and appears to have a 3/4" gap behind it all. 

would it be worth it to put 3/4" foam board behind it? aside from only covering half the walls, there's also the firing strips that take up space behind it.

The other option is to open up the wall behind the wainscoting and get insulation into the exterior walls from there, and the wainscoting will cover up the demo(properly sealed/patched) The house has at least some rockwool in the walls (1947), and aluminum siding which has half inch foil faced insulation, over the original clapboard

Thoughts? another thing i can do is line the closets with more foam board(exterior and roof backing the closets)

And on the topic of foam, i'm in NJ, would you recommend the pink board, or the foil faced? I understand the concept of the foil face is to reflect heat back into the space, but would love opinions as to the effectiveness.

thanks!


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## Windows on Wash (Aug 30, 2011)

If you have a vapor impermeable foam on the outside and put a similar vapor impermeable foam on the inside, the wall cannot dry in either direction at that point. 

I would focus more on the air sealing of the walls while the demo is going on and add more batt insulation where you can. 

Airtight Drywall Approach (one of Gary's favs). 

https://buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach


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## DarrenLevine (Aug 3, 2016)

Thanks for the input,

I was concerned about that as well, but curious if these factors make a difference in that:

-the exterior insulation is in 1' rows, as is such with aluminum siding, so there is a gap at ever 1' height, is this considered vapor permeable?

-in the wainscoting there is plenty of furring strips which the foam would be cut to fit between, which would compose perhaps 20% of the surface area, would this also be considered vapor permeable?

In all, would these two factors be enough permeable to allow safe use of foam board?

i'm unaware of any other insulation options in 3/4" that aren't vapor impermeable, but if such a thing exists, would love to know about it.

thanks again


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## Gary in WA (Mar 11, 2009)

Darren, are you still around?

Gary


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## DarrenLevine (Aug 3, 2016)

Gary in WA said:


> Darren, are you still around?
> 
> Gary


Yep!

Just got a second coat of poly on the bedroom floor  

new thoughts on the insulation?


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## Gary in WA (Mar 11, 2009)

Just send him a PM, he will answer you.

Gary


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## Gary in WA (Mar 11, 2009)

I notified him for you, he'll be here after his coffee...

Gary
PS. need pics of your work!


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## Windows on Wash (Aug 30, 2011)

DarrenLevine said:


> Thanks for the input,
> 
> I was concerned about that as well, but curious if these factors make a difference in that:
> 
> ...


What is the exterior insulation comprised of? 

The gaps in the 1' rows only changes the vapor permeance in those gaps and does not impact the vapor permeance of the wall at those other locations that are covered by the foam. 

While the 1' gaps will allow for air flow and that has a drying potential, it also allows for air flow and vapor drive in the other direction. 

EPS (with the right facing) is a fair vapor open foam and if you were going to cut and cobble sections behind the wainscotting, that is what I would use.


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## Gary in WA (Mar 11, 2009)

Just to back-up what was said; "aluminum siding which has half inch foil faced insulation, over the original clapboard"-------*no facing* on the interior insulation board.

SOP for the alum. siding was the ff XPS rigid board (big sale point), the siding has the gaps where it laps, the foam is usually continuous, IME. Ever think about removing it; http://renovatedsm.org/what-lies-beneath-aluminum-siding-part-1/

https://thecraftsmanblog.com/how-to-remove-aluminum-siding/ to find what is underneath?

Use the pink board, or blue- unfaced- if leaving the ext. foam. XPS on the inside has enough drying power one-way, and you are leaving the top alone- even better--- "
The Misconception of Foam Plastic Insulation as a 
“Double Vapor Barrier”"; http://commercial.owenscorning.com/assets/0/144/172/174/e45fe07d-5cc9-4e4b-866a-5e35d75090ec.pdf
Gary


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## DarrenLevine (Aug 3, 2016)

thanks for the input fellas,

removing the siding just isn't an option at this time, maybe in the future. I'm really just looking to see if i can get some improvement with little hassle at this time for this one room. 

So, would i be correct that EPS, unfaced, in 3/4" would be the way to go and is fairly vapor permeable?

Let me know if you think i'm wasting time/money for too little a benefit. But aside from the wainscoting, i can feel a ton of cold coming from the closets which are built into small dormers, and i'd like to line the inside of them with insulation as well, presumably the same EPS unfaced.

Thanks again for your input, much appreciated.


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## Windows on Wash (Aug 30, 2011)

Do not assume anything, but EPS is your best option. 

Best to check with the manufacturer on what the perm ratings are.


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## DarrenLevine (Aug 3, 2016)

The brand at HD lists perm rating of 2.0-5, doesn't specify each thickness, presumably 1/2=2.0, in any case, is 2.0+ perm rating sufficiently permeable for my application?

cheers


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## Gary in WA (Mar 11, 2009)

Either closed cell (XPS) or open-cell (EPS) is fine for your application. I suggested XPS in case you don't have a vapor retarder (and need one per location) eg.; asphalt coated paper-faced fiberglass or other; sometimes foil-faced was used in early years... I think that came out in the late '50's but not positive. SO... if you live in Climate Zone 5, or Marine 4 (coastal counties) the lower vapor perms would help stop moist indoor air from condensing on the outer sheathing; http://energycode.pnl.gov/EnergyCodeReqs/index.jsp?state=New Jersey
Check local AHJ; may have different requirements for you.

Gary


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## DarrenLevine (Aug 3, 2016)

To sum the details:

house is 1947, climate zone 4
original siding is clapboard
over that is aluminum with 1/2" foil faced EPS
in the walls(dont know if in all walls) is gold bond rock wool
ceiling in the room is 7'
wainscoting goes up 4'
3/4" space behind the wainscoting

HD carries cellofoam EPS in 3/4", perm rating of 2-3


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## DarrenLevine (Aug 3, 2016)

Update: finally got some time to work on this.

I bought insulfoam EPS panels, and began cutting and piecing things together.

Because i'm a dolt, i forgot i wanted to run an outlet before gluing and nailing a piece up, so now i'm giving everything more of a think through.(like i should have in the first place)

Question for the gallery: 
there is space between the top of the heater enclosure and the wood above, enough space to run romex, and some of the 3/4" foam. It's hot water based heat, and i'm probably over thinking this, but is the foam OK to be sitting on top of it? I have my boiler at 185F, so by the time it hits the fins, it's certainly less, and there's 2 feet of air between the fins and the top of the enclosure.









On the topic of glue... i did get some panel board glue, but i'm wondering if folks feel it's necessary. the wainscoting i'm removing was only nailed, and since the new beadboard isn't paintable, i'm thinking about what if i need to replace a damaged board in the future. The beadboard gets secured at the top, middle, and bottom to the furring strips.










Lastly, are there any tips on the seams? the first boards i butted i gave a round of caulk, and while it looks OK, i can spot the seam pretty readily. Maybe just another round of caulk? Same goes for the nail holes, i'm keeping them in the trenches, but of course i can still spot them even after a round of caulk. The before and after pictures kinda make it look better than in reality.

Before








After









As always, thanks for your input


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