Insulating Our Basement Furnace Room
Feb 28th, 2014 by Sarah
Our last few posts have been about older projects as we try to get the blog up-to-date with everything that’s been going on around the house, but I figured it was time to also share what’s been keeping us (or mostly Chad) busy recently – and that would be installing insulation in our basement furnace room.
I’m not sure if we’ve ever shared a lot of pictures of our basement – or really even taken many, for that matter – but here are a few of the furnace room before we started working on it. To be fair, the next two are actually from when we toured the house with a realtor before we bought it (so, not our stuff). I was also clearly more focused on the storage component of the room than the furnace/walls when I took the photos, but you get the idea:
And here is the only picture I can find of the room since we moved in – and it’s also not a great one. (Clearly, I was a bad blogger and forgot to take any fresh photos before we actually started working in the space … tsk tsk.)
So, basically, the room is in the center of the basement and holds both the furnace and a decent amount of storage. The walls on either side are interior block walls that were previously covered in pegboard. That back wall is the exterior block foundation wall. It’s also where we’d like to locate a tankless water heater at some point in the (hopefully not too distant) future. In preparation for the water heater being re-located to this room, we thought it would make sense to finish that back wall off – insulate it, build a stud wall, face the wall with something (probably fiber cement board), and generally seal it up and prepare a fresh, dry, solid surface for mounting the new water heater.
The first thing we did in this space was to completely clear out the room, removing all of our stuff as well as the old shelves and pegboard from the walls. (Taking out all the shelves might seem like an unnecessary step, but it gives better access for installing the new water heater and will allow us to re-build shelves that provide more efficient storage for our stuff when we’re done.) With the room cleaned out, Chad then scraped off all of the bubbling paint from the block wall and applied a couple of fresh coats of water proofing paint. We’ve never had a moisture problem in this room (that we know about), but the bubbling / effervescence on the wall made us think some waterproofing paint might be a good layer of protection anyway.
We (and, by we, I mean Chad) then glued 2″ of extruded polystyrene (XPS) insulation to the wall using an adhesive formulated for foam. We chose not to screw the sheets of insulation to the block wall (which would be the standard process) and relied on just the glue to hold them in place instead. We did this primarily because we didn’t want to introduce any more holes into the old block wall in case that might make it more vulnerable to water, etc.
Once glued, we sealed up the seams with foil tape and then added a layer of 1/2″ sheets of foil backed polyisocyanurate foam sheathing (also glued in place with an adhesive meant for foam). We taped the seams between these sheets with foil tape also and sealed any gaps around the sides with “The Great Stuff” spray foam insulation. (By the way, did you know they sell a “professional” version with a separate, reusable insulation gun? A total game changer.)
We chose to follow up the standard pink extruded polystyrene insulation with a sheet of the foil backed polyiso foam sheathing just to be extra thorough. This combination makes the wall waterproof (in case there were ever any issues with moisture seeping in through the foundation wall), insulates the space really well, and acts as a vapor barrier. Chad did a bunch of research online before deciding on this approach – here’s a link to some more information on this method of insulating a basement wall in case anyone is interested in reading on.
And here’s what that wall looks like now, with all of the insulation in place:
It’s funny because neither of us really would have said that the room felt cold before. The foundation wall was cool to the touch, but we definitely never walked into the room and felt like it was drafty, cold, or otherwise in need of insulation. Once the foam sheets went up on the wall, though, the room feels noticeably tighter. The difference is pretty amazing.
So, our (really, Chad’s) next steps will be to put some additional insulation around the rim joists (we had foam insulation sprayed up there in the fall, but there’s still quite a gap, so we’re thinking we’ll just use some scraps from the polystyrene sheets to fill in that space) … and then it’s on to wall building.
Speaking of which – any guesses on how long it takes a frozen 2 x 4 to thaw and dry-out? It’s definitely in the “days” category …
And I really have no comments on the rug collection in that last picture – they (along with partially full paint cans) seem to reproduce in the basement. For every one I remove, it seems like 3 more show up … maybe we’ll get ahead of it one day.
Filed Under: Home Improvement