Hey guys. I have a block house with aluminum siding. There doesn't appear to be any insulation under the siding currently and adding insulation to the inside won't work because the walls are plastered right over the block...I'm going to be replacing the siding this year and adding insulation to the block (under the siding) - I would think furring strips will be the best solution to attach the insulation AND the siding? Is there anything that I should watch out for? BTW - I'll be replacing windows at this time also....
Make sure you apply a house wrap over the insulation as your primary moisture barrier. sidings are not considered a primary moisture barrier. Rigid insulation between the furring strips would be far better than fiberglass.
When you have the new windows installed, make sure they are installed by a certified installer or at least try to follow the manufacturers installation requirements.
Cut foam insulation in between the furring strips. Don't leave a gap between the block and the insulation for air to travel. It will make your insulation next to useless. You can add a second layer over the srips and the first layer and nail the siding through it. I'm not sure about housewrap over foam board insulation. I've never seen it done, but I can't imagine it would hurt anything. You probably want to put solid blocking around windows and doors to attach J-channel and along the bottom for starter strip. You'll want to watch your window and door furring and wrapping details so you don't create a place for water to get behind the insulation.