How do you insulate an exterior wall from the outside?
We live in an old frame farmouse. I need to replace the the board and batten on one wall. We want to insulate this wall (currently, there's literally no insulation in it). I spoke to a spray foam contactor, but they were quite expensive. I"m wondering if I remove the board and batten, then remove the old exterior plank wall, if I can just add fiberglass into the wall spaces and is there a product that has some kind of a vapour barrier attached. (We don't want to open the inside of the wall, as it's a newly renovated kitchen!) The total area is about 8' x 40', less a couple of doors and windows.
I'd apprecialte your advice/suggestions!
Thank you!
Spray foam will work well for exterior walls because it acts as the air barrier, the vapor barrier and the thermal barrier as well. But yes, sometimes the price can be a bit prohibitive. However, it does work well and you also need to consider that any other material and install technique will significant labor costs to consider. Some spray foam manufacturers have switched to climate friendly blowing agents, so we’d suggest you try one of those. As for options other than spray foam, this page should tell you all you need to know –
How to Insulate Exterior Walls from the Outside
Another idea and product comes to mind, if it’s a farm house I’m assuming you have wiggle room to make the wall thicker without affecting propertly line setbacks? If so, here is my thought – a thick panel of rigid foam insulation would provide you with a vapor barrier along with being the insulation. Specifically there is a ThermalWall EPS foam panel from Legalett that is perfect for such renovations, it attaches easily with short screws and breaks the thermal bridge to reduce heat loss.
The one thing to remember is to keep at least 2/3rds of your insulation on the exterior of the vapor barrier. so in your case, and another assumption is that it is a 2x4 wall, that you would have room for 3.5 inches of insulation. So if you put at least 7 inches of EPS foam on the outside then your vapor barrier (the EPS) would be perfectly placed. Also, you could just leave the stud bays empty and instead pop on maybe an 8 inch panel of foam, that would be a seamless R32 wall, which is far better insulated than 90% of the tract homes being built today.