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Questions about insulating a concrete sun room.

Hey folks! Thanks in advance for any advice and/or help on this matter.

I'm currently working on a renovation project in my sun room. I live in a 1939 brick cape cod and am working on an addition (I suspect it was done in the 70s) that is made of cinder block on concrete slab and the dreaded flat roof. I had the roof redone a couple of years ago and am finally getting around to finishing this thing up.

Basically I have stripped everything down to the studs (they aren't really studs but rather 3/4 in boards leveled and nailed into the cinder block) and am wondering how to insulate this bad boy. I think I want to use 1/2 inch (this fits with the current wall structure) R-matte plus 3 insulation. I got a 4x8 piece to test out and it's easy enough to cut and fit into the wall sections. There is only a small gap between the cinder block and the edge of the studs. After insulating I am doing pallet walls on three of the 4 walls, the fourth will be exposed brick. The room has no insulation and I figured something was better than nothing.

I will not be insulating the ceiling and will infact be keeping it exposed for both esthetics and ease at this juncture in the game. I'm aware I won't be getting the best bang for my buck but this is where I'm at. It's possible I will decide to put a hard ceiling in later on which is why I want to insulate the walls now just incase.

Will the r-matte work? Will an adhesive be enough to stick them to the wall prior to nailing in the pallet sections? Do I need a vapor barrier/thermal barrier? Lastly I need to put the foil side towards the outside and not the inside correct?

I hope I explained this well enough. Our goal here is to have a rustic feel in the sun room which is why we are doing pallet walls. I want to at least attempt to do the best I can in terms of insulating while I can. I'm open to other suggestions and again I appreciate anyone's advice!


Re: Questions about insulating a concrete sun room.

If you are not insulating the roof, why are you bothering with the walls? In terms of comfort, both winter and summer, the major heat loss or gain is going to be through the ceiling.

If you are in a cold climate, that room is going to be cold. Sure, you can overpower it with a heater, but very inefficiently. Also, on a cement slab, that room is going to be very foot cold and uncomfortable. In terms of comfort, you would be better off using that thin foam to insulate the floor.

Re: Questions about insulating a concrete sun room.

What he said.

Re: Questions about insulating a concrete sun room.

While not cost-effective, you are right to insulate this before closing it in so that you don't have to tear it out to insulate later should you decide to condition the space in fully somewhere down the road. I don't understand your reference to 3/4" studding; are these furring strips applied to the concrete block walls? If so then 3/4" foam panels will help but I'd be just as concerned with their thermal conductivity so I'd cover that with an additional 1/2" of foam under the sheetrock or other walling material being used. Use long fasteners to engage the furring strips through that layer. You might also consider building an independent stud wall here that does not contact the concrete block to break that thermal path, but that has drawbacks in equal or higher cost and loss of some floorspace even if it does have better insulating properties. If the 3/4" 'studs' you refer to are not attached to the concrete block wall, then build this type of wall as they are not allowed to be used for wall structure alone.

Looking ahead at possible future changes often alters the approach you want to use today so that those changes can be more easily implemented. I hate nothing more than demolishing perfectly good work I've already done to accommodate changes which could have been foreseen and allowed for had someone mentioned the possibility when I did the initial work.


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