How to Insulate a Stucco Home
LESLIE: Brad in Massachusetts is on the line and wants some help with insulation. What’s going on at your obviously chilly home?
BRAD: Well, we’ve got a stucco house, three story. It’s a Japanese-style Arts and Crafts.
LESLIE: Ooh, that sounds gorgeous.
BRAD: Yeah, it’s different. It was designed by a fellow by the name of Ralph Adams Cram, who was a noted architect back in the day.
There’s no insulation. We have a cold basement and it’s stucco, as I said. There may be firestopping, I’m not sure, you know, in the walls. And it – that’s unclear. But I’m worried about moisture, so – I’m also worried about a fuel bill. So, what I’m looking to do is – how do I insulate the house and – so that we can be warm all winter in this cold part of the United States and at the same time, make certain we don’t introduce moisture problems from trapped water?
TOM: Well, first of all, this is a wood-frame wall?
TOM: So, this is a good reason to use blown-in insulation. And so, blown-in cellulose, maybe blown-in fiberglass, coupled – it has to be installed by somebody who really knows what they’re doing, because they’re going to use an infrared scanner to determine those cold spaces. Because you mentioned it may have firestopping. If it turns out you have firestopping for every bay – every section of open 2×4 – you may end up with two holes instead of one. Once they figure out sort of the lay of the land, then I would blow in insulation into those cavities. And that’s going to warm up those walls quite a bit.
If you use cellulose or fiberglass insulation, I wouldn’t be too terribly concerned about moisture because I think those walls are going to breathe, based on the age of that house. And it’s really not practical to do any kind of vapor barrier at this point.
BRAD: Yeah, yeah, OK. So, he has to do the due diligence to make certain he fills all these bays up and everything.
LESLIE: Yeah. But you’d be surprised. I mean I did this in my home at the beginning of – well, it ended up happening at the beginning of the fall. And I did notice a big change in it but I was really surprised that the contractor who did the insulation, which was blown-in from the exterior – and I saw the holes and I saw the pink stuff flying out of it. But nobody would come in and do a thermal scan to show me that the bay – because it’s like a mystery. You’re like, “Is it really in there? Did you really do it?” And I would love to see that to know that, truly, those areas are all filled.
BRAD: Right. OK. So, is that normally done from outside rather than coming in and tearing up my wallpaper and everything?
TOM: Well, you have the option of doing it from outside or inside. Now, if it’s stucco and you’re going to repaint the house, repairing stucco is pretty easy and it’s supposed to be rough, so that might be the way to go. Or a combination. If you’ve got some rooms with nice wallpaper, maybe you leave those rooms alone. But if you’ve got some rooms that are just plain, old drywall, then you go ahead and go at it from the inside.
BRAD: Any choice between fiberglass or cellulose?
TOM: I personally prefer cellulose. I think that it packs better and it’s got fire-resistance built into it, so you don’t have to worry about that.
BRAD: Alright, good. Thank you so much.