When renovating solid masonry homes, we fully realise that the two layers of structural brick have little to no resistivity to heat flow – or no R-value. Knowing this we use one of two strategies in deep energy retrofits; we wither insulate completely on the outside, or we insulated completely on the inside.
We come into issues where this solid wall either can’t be insulated for firesafety, where the wall’s brick is exposed and highlighted or where it makes an incursion into the warm space and this applies almost always to converting back porches into heated spaces or when adding an addition to the back.
We covered the fire safety issues in a previous post – Tip No. 1 and quite simply for those of you who like the exposed brick look, don’t sacrifice your comfort for aesthetics, insulate the wall and cover it with frick (Fake Brick).
The most difficult case is when the back wall remains mostly intact as in below (note the grey left half of the picture with faint red vertical lines) leaving the pourous wall to bleed heat comfort by way of thermal bridging and air leakage.
The most obvious course of action is to either simply insulate the wall on both sides and air seal it even if it feels like an “inside wall” the other is to open up the back wall and put in structural steel to hold up the brick on the 2nd story back wall. In the latter case, the steel needs to be well insulated and sealed. Either way this wall needs to be taken care of in case where high performance is desired.
The back wall (the grey left half of the picture with faint red vertical lines) will bleed comfort out by way of thermal bridging and air leakage. See infrared detail of same area below. The back porch was annexed and will now be conditioned space, see visible picture below for the other side of this picture.
The back wall (the purplish left half of the picture ) will bleed comfort out by way of thermal bridging and air leakage. See visible light picture above.
What used to be the back wall of the house is now inside the house bleeding heat and leaking cold air into the house. See below for infrared equivalent.
Corresponding to the visible light picture above, the back wall of the house is now inside the house bleeding heat and leaking cold air into the house at all corners.