So, a client wanted to get a bit more info about spray foam insulation, and our contractor provide some good content that I thought I would post for future reference.
Lewis, I can certainly speak some towards spray-foam..
Firstly, it depends on the depths of the cavities and how much the owners want to fill in. BASF literature recommends a layer of at minimum 2.5 inches in the walls to obtain that complete air and moisture barrier that most people have as their primary reason for spray foaming. When we do that, we typically use an R11 batt over the top of the 2.5 inches to finish filling the cavity 1) for R-value code, and 2) Insulation cannot have a void between itself and the drywall or mold can build from the opposite side. Depending on the market, prices can fluctuate a bit. Filling a cavity with spray-foam is costly and is most times overkill. I didn’t even full cavity spray my own house, I used the above “hybrid system”.
Mostly we use a full cavity spray in retro work where there isn’t enough room to fit batts to make code, and use it in lieu of cutting rigid board into things.
In stick-framed ceilings I like to use at least 3 inches to ensure that air and moisture barrier, per BASF specs, and then overbatt with whatever fills the particular cavity to code be it a vault or a flat ceiling. It can also be sprayed over drywall in a blown-in ceiling situation, which I particularly like as a fan of blown in insulation. We wait for the drywallers to finish their part and then have the crews come in a few days apart to finish up the attic in two phases.
If someone can afford it, sprayfoam is a great way to go. It is health-conscious and aside from the day it gets sprayed in is as green as it could possibly be, and BASF constantly works on making it more so. The air and vapor barrier in a state like this that has constant mold problems is a piece of mind that I know I personally won’t do without, seeing the insides of retro walls on a daily basis. I trust that when I have to open up my own walls to do something they’ll look just about the same way they did the day I got them blown in, even years and years down the road.
Thanks Lewis, hope that helps, any specific jobs you want me to add it as an option/upgrade just let me know in the specs.
Thanks Josh from Masco!