On Sun, 05 Dec 2010 14:02:51 -0800, mike wrote Re
What's the R-value of a fireplace?:

I've got this red brick fireplace taking up half a wall.
Capped the chimney decades ago, but it's still siting
there conducting heat outa' the place thru the bricks.
How would one go about calculating the "R-value"
to estimate the heat loss. Any useful rules of thumb?

Brick has an R-value of 0.8 but there are other materials behind the
brick. You'll have to identify them and add their R-values to the
brick.

http://www.coloradoenergy.org/procorner/stuff/r-values.htm

Trying to decide whether to put insulation over the bricks
on inside or outside or both.

Both if you can do it.
--
Work is the curse of the drinking class.