r-value of glass block windows

[Bob Weisner]

Hi:

Does anyone know what the r-value of glass block windows is?

Thanks,

[Ken Garlock]

Hi Bob. A quick google lead me to a building products vendor that sells Pittsburg Corning glass blocks. The standard 4" thick block has an R value of 1.96, and the thinline 3" thick block is 1.75. Not exactly good, and less than 2" of wood.:(