Photo Explanation of my Floor, with bonus insulation excitement
Yesterday I planned to fully insulate my floor, so I could have a framing/insulation inspection done Tuesday, and get actual subfloor down this weekend. Slightly complicating this, I was also engaged in some familial diplomacy/trade, which is to say I was required to employ my brother, funded by my parents, so that he'd be out of the house doing something useful and my mother wouldn't kill him.
Starting the day, I figured I'd have A drive me out to get insulation, then I'd send him out again to get more (since the Escape would be full), with cash or a gift card or something. I was actually pretty pleased to have him driving, 'cause it just exhausts my foot, lately.
Anyway, we ran my grocery errands just fine, then ran into a wall at Home Depot. They didn't have any unfaced fiberglass batt insulation. They didn't have any unfaced 3.5" thick fiberglass insulation at all! Since fiberglass insulation is still the simple, cheap standard, that was unexpected. We trucked off to Lowes... where they also didn't have it.
Apparently no one stocks unfaced fiberglass anymore. Whut.
At Lowes, though, we found a different kind of unfaced batt -- Rock wool. I only knew rock wool as the crappy fluff in old attics. I've shoveled it, but it didn't show up on my research radar as a current thing at all. So I had a bit of a dither in the aisle at Lowes, sitting on my ass (because screw this standing thing), frantically googling 'rock wool batts' and calling emony42 to google rock wool batts and calling my dad and generally trying to figure out if this shit would work or was a disaster.
(Brother did a bit of googling on his phone, then pushed himself around on the trolley. I don't blame him. It looked kinda fun.)
My other options were special ordering fiberglass, using some kind of rigid foam, or potentially blow-in. All would take more time, to research, order, cut-and-fit, etc, and possibly more money.
I should note at this point that my floor assembly is weird, and my standards are high, so I wasn't even exactly sure how to get what I wanted with fiberglass -- I was just going to buy the first few bags and wing it, see where it got me. I bought a bag of the rockwool batts, instead, and we took it home to experiment.
PLOT TWIST: Rock wool works really well for this, actually! Look at the bit laying under the joists nicely there:
That insulation is between 1" and 1.5" thick, and I got it from a 3.5" thick batt by filleting it with a bread knife. The Rockwool is dense enough that it pretty much sorta works. In retrospect, I've no idea how I thought any of my earlier plans would succeed -- I was going to have to rely on stacked 2" thick fiberglass marketed for craft projects to get anything under the joists, and that would've been a pain in the butt..
Here you can see the wall, the joists attached with hangers, and the sleepers running perpendicular to the joists underneath. The black plastic underneath everything is the vapor barrier, which sits on the concrete slab of the original garage floor. The white frosting dribbling along the base of the wall is spray foam insulation, which hopefully does a bit of air sealing between the cement foundation and the wooden sill plate. Another layer of insulation will be laid down in the joist bays, perpendicular to the current one.
That last pic is about as much as I got done yesterday. I knew I couldn't manage to get the whole thing done, since I started hours later than planned, so it made more sense to do a sample section. The inspector will still come out tomorrow to check over the framing, and hopefully he'll give the insulation plan the go ahead then, too. If he doesn't, I'll have less to rip out...
Starting the day, I figured I'd have A drive me out to get insulation, then I'd send him out again to get more (since the Escape would be full), with cash or a gift card or something. I was actually pretty pleased to have him driving, 'cause it just exhausts my foot, lately.
Anyway, we ran my grocery errands just fine, then ran into a wall at Home Depot. They didn't have any unfaced fiberglass batt insulation. They didn't have any unfaced 3.5" thick fiberglass insulation at all! Since fiberglass insulation is still the simple, cheap standard, that was unexpected. We trucked off to Lowes... where they also didn't have it.
Apparently no one stocks unfaced fiberglass anymore. Whut.
At Lowes, though, we found a different kind of unfaced batt -- Rock wool. I only knew rock wool as the crappy fluff in old attics. I've shoveled it, but it didn't show up on my research radar as a current thing at all. So I had a bit of a dither in the aisle at Lowes, sitting on my ass (because screw this standing thing), frantically googling 'rock wool batts' and calling emony42 to google rock wool batts and calling my dad and generally trying to figure out if this shit would work or was a disaster.
(Brother did a bit of googling on his phone, then pushed himself around on the trolley. I don't blame him. It looked kinda fun.)
My other options were special ordering fiberglass, using some kind of rigid foam, or potentially blow-in. All would take more time, to research, order, cut-and-fit, etc, and possibly more money.
I should note at this point that my floor assembly is weird, and my standards are high, so I wasn't even exactly sure how to get what I wanted with fiberglass -- I was just going to buy the first few bags and wing it, see where it got me. I bought a bag of the rockwool batts, instead, and we took it home to experiment.
PLOT TWIST: Rock wool works really well for this, actually! Look at the bit laying under the joists nicely there:
That insulation is between 1" and 1.5" thick, and I got it from a 3.5" thick batt by filleting it with a bread knife. The Rockwool is dense enough that it pretty much sorta works. In retrospect, I've no idea how I thought any of my earlier plans would succeed -- I was going to have to rely on stacked 2" thick fiberglass marketed for craft projects to get anything under the joists, and that would've been a pain in the butt..
Here you can see the wall, the joists attached with hangers, and the sleepers running perpendicular to the joists underneath. The black plastic underneath everything is the vapor barrier, which sits on the concrete slab of the original garage floor. The white frosting dribbling along the base of the wall is spray foam insulation, which hopefully does a bit of air sealing between the cement foundation and the wooden sill plate. Another layer of insulation will be laid down in the joist bays, perpendicular to the current one.
That last pic is about as much as I got done yesterday. I knew I couldn't manage to get the whole thing done, since I started hours later than planned, so it made more sense to do a sample section. The inspector will still come out tomorrow to check over the framing, and hopefully he'll give the insulation plan the go ahead then, too. If he doesn't, I'll have less to rip out...