Hard Time Calculating R Value of Brick Wall

DIYSteve

Another DIYer here. I am converting a 120 year old 2 flat in Chicago to a Single Family Home.



I am having trouble coming up with a heat loss number for my primary living area. The space is pretty big - approximately 31 x 20 (620 sq ft) with 10 ft ceilings. It is 4' above grade with a heated basement below and a second floor above.



I put all of the design elements into RadiantWorks and get a heat loss value between 19 and 26 btu/ft/hr. The difference mostly depends on the R value I assign to the exterior walls.



Here is what I have:



~14" Chicago Common Brick wall (3 bricks wide).

2x4 framing, laid flat

1.5 inch batt insulation (I can pay more and get Tuff-r board)

drywall



My current thinking is I probably have an R value of 3-5 on the low end and 10-12 on the high end.



Any thoughts / wisdom greatly appreciated!



Thanks!

Gordy

Wall R Value

Common Brick .80x3=2.4

1.5" Fiberglass inulation 3.14 per inch x 1.5"=4.71

1/2" Drywall .45

Outside air film = .17

Inside Air film= .68



Total R value  = 8.41



A little more could be added for the mortar between the rows of brick.



Gordy

Bob Harper

moisture content makes a difference

The industry figures for the R value of common brick are based upon dry bricks-not wet. In reality, bricks are a moisture storage system that CONDUCTS heat until dried out. That is why it is so important to have a proper drainage plane behind brick veneer and why masonry chimneys are such heat sinks---they don't have drainage planes.