Hi all,

I’ve put a lot of work into insulating my attic cathedral ceiling. Before I get a crew to drywall the attic ceilings and walls, I’m trying to figure out what to do with the two triangular brick walls at either end.  When I bought the home 2 years ago, there was 2×4 framing against these walls with rock wool batts between and drywall over that. The rockwool was right against the brick—which, as I’ve read here, is not advisable.

I removed the drywall and pulled back some sections of rockwool to look at the brick and didn’t see anything too concerning. The house is 1930s and the rock wool’s been there at least 50 years.

ive also looked closely at the brick on the outside of my home, especially on the chimney and parapet. Everything there seems to indicate that I have good bricks as there isn’t any visible evidence of damage from freeze/thaw. 

im wondering what to do about these walls in terms of insulation. Seems like the safest approach would be to pull the rock wool and cut and cobbled in some rigid foam between the 2x4s. The evidence above, however, seems to suggest that I could get away with leaving the rockwool, maybe adding a layer of rigid foam over the 2x4s to minimize thermal bridging through the 2x4s, and then Drywall through the rigid foam and into the framing.  This would save a lot of old insulation from a landfill too.

i should mention that the house is at the northern edge of NYC  

advice?

thanks, Matt