That’s what we’ve been thinking a lot lately, so it was nice to have some hired help insulate the apartment for us.
The county determines how much insulation you need. Insulation is measured by R-value, resistance to conductive heat flow. Higher R-values mean higher insulation properties. In our climate we need R22 for exterior walls. You can achieve this with any material you want. The three common types of insulation are spray foam, fiberglass, and rockwool. We decided to use spray foam in the exterior walls because it does a great job sealing the walls.
R22 amounts to 3 inches of closed-cell spray foam, which is typically used on exterior walls. Closed-cell foam is dense and doesn’t allow air and condensation to pass through. Three inches of foam covers most of the wiring within the walls. The foam is solid when it dries, making making all of the wiring inaccessible. This made us nervous, so we added some extra wires for internet, motion sensors, and a few multi-conductor wires we might want in the future.
The cats were bored watching Sam pull wires for hours, so they got up and helped.
We were finally “done” with wiring in the apartment!
A single guy did all of the spraying. The foam is formed by mixing two materials. They get mixed in a truck outside. Then the mixture is pumped through a hose and sprayed onto the wall. It cures in just a few hours. The foam produces a lot of toxic gases when it is applied, so I don’t have any photos of the process. This is the end result…
We aren’t insulating the attic, but we are insulating the living room ceiling which requires R38. Since it’s an interior location, we chose an open-cell foam which is more permeable, allowing air to pass through. (It is also much cheaper.) It has a lower R-value per inch so you typically need more of it. To achieve the R38 requirement, we need to fill the entire 9 inch space between the ceiling and the attic floor!
We also used open-cell foam under the office floor (bedroom ceiling) since that floor has radiant heat. Foam is the best material for reducing heat loss, and open-cell foam is great for reducing sound because it has a lot of air bubbles. The open-cell foam bubbles up a lot when applied and needs to be shaved down with a knife when dry.
I think we’ll be happy with the foam. On 100 degree days, the insulated space felt significantly cooler than the rest of the shop.
Since spray foam is costly and less advantageous to use on interior walls, we decided to use rockwool on the interior walls. Rockwool provides more noise dampening and is fire resistant.
Sam and I were also concerned with vapors, particles, and noise getting transmitted from the shop into the apartment. Rockwool seemed like the best insulation material to meet our requirements.
Per code, the wall that divides the apartment from the shop has to be fire resistant. Prior to stuffing the walls, we used a fire-proof caulk to seal all of the holes around wires and ducts.
Rockwool is an interesting material to work with. It is slightly more structural and less messy than fiberglass (the pink stuff), but it still releases a lot of itchy particles into the air.
The crew used a tool that looked like a steak knife to cut it. They measured around everything and cut pieces very quickly. Then they stuff the bits of material between the studs. The walls were so stuffed they looked like they might burst. In fact, we had to push some of the pipes back into the walls.
We were so exciting to be done with part of the insulation. Unfortunately, the cats were excited too. They love ripping rockwool out of the walls. After arriving to a rockwool crime scene multiple mornings in a row, we blocked most of the walls off with cardboard and temporary doors. What a mess!
We’re looking forward to getting it all covered up with drywall.
As for the shop, we are still working on electrical odds and ends, so we’ll be getting that area insulated a bit later.