Q&A R-Value of fireplaces

Question:

I am an architecural engineering student designing the heat load and
cooling loads in a house for one of my classes. In our house there is
to be a fireplace of our choice. My instructor directed me to the
internet to find an R-value for any fireplace, but I can't seem to find
any manufacturer that lists this for their products. Can you give me any
product and an R-value for it?



Answer:

There are two types of fireplaces, factory built (metal) and masonry (usually site built).

Metal fireplaces are installed inside a structure, so they do not provide an insulating factor by themselves. Many are simply two pieces of sheet metal with an air space between them, so they are of little R value.

Masonry fireplaces differ in construction. Many use an outside layer of 6" block, which might have a brick veneer on the outside...or it could just be stuccoed. Inside, a layer of firebrick completer the firebox. An airspace may also be present. Pourable insulation is sometimes used in the outside blocks, which would increase the insulation factor.

Since these are site built, a specific R factor would be hard to give, but I'm sure you can figure one out based on these specs. You could also try the masonry links at http://www.rumford.com

Link: Masonry Links