was there a “better” way for me to insulate this 2′ kneewall?
in hindsight, i should’ve asked before doing my own thing . i did spend a whole 15 minutes googling how to insulate a 2′ kneewall where the interior ceiling height changes from 8′ to 10′. the wall was already covered by osb and has blown in fiberglass, so somewhere around r13-r15.
https://www.energyvanguard.com/blog/how-to-insulate-a-short-attic-kneewall/
i found that, but i had a few holdups on those options. i did not want to mess with sprayfoam. plus, the cost was too much. i had around 60 linear feet of this knee wall to deal with.
to get adequate insulation over the top plate, i’d pretty much need an entire 4×8′ of osb or plywood which wouldn’t fit through the attic opening. then i’d have to do some type of framing to stand up the sheet of wood.
…so i did the framing to hold up a “wall”, skipped the 4×8, and used netting to essentially treat it like blown in for an exterior wall.
i had an abundance of 16 and 24″ r-30 fiberglass batts. so for one portion i placed the net about 18″ from the wall and used a couple of layers of the 16″ batts before the cellulose, then around 26″ for the 24″. i did agitate the fiberglass and cellulose as i was blowing it, to help it settle around in the cracks. theres about 16″ of cellulose cover the top plate. r-30 is code where i’m at, so 16″ is great.
previously, the 8′ portion had about 10″ of insulation going up the short wall, then the 10′ portion had fiberglass batts covering the top plate, with more running perpendicular. obviously that left a lot of open space. a crazy amount of heat was radiating to the interior through the 10′ ceiling rooms near the top, so i’m hoping that will fix it.
just curious how other people handle this?
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Replies
That looks to me like blown in cellulose, not fiberglass. That's a plus -- cellulose is usually the better option, and it's much less itchy!
What I have done in the past is to put a layer of polyiso on the attic side of the kneewall, then mineral wool batts in the stud bays. This works pretty well. There are some advantages from an energy performance standpoint to insulating the roof deck instead, which can usually done without using spray foam. If you have a vented roof, you can put vent channels under the sheathing beneath the rafters, then use batts between the rafters and either more batts under the rafters, or some type of rigid foam. The vent channel avoids the need for spray foam here.
I find that insulating the roof deck is sometimes more difficult than insulating the kneewall though, depending on the way the building is framed and insulated, and also how much access you have to the atttic space to be able to do the work.
Bill
yea, i went with cellulose. home depot started to carry "unbranded" 25 pound bags for $15.99 with free shipping and still qualified for the free blower rental. bought 40 bags and did the knee wall, touched up other areas and added more insulation above the garage. the green fiber brand is $18 a bag after the discount for buying x amount and shipping is $79...
i did consider the foam board route, but there romex running across pretty much every foot of osb. so that was kind of annoying.
https://imgur.com/a/v6AvhI1
theres another angle + a before picture.
i tried my best to get blown insulation to cover the osb, but without any way to hold it in place that just wasn't happening. not pictured is the fiberglass running perpendicular on the before picture x)
insulating the roof deck would be the dream. my house isn't large, just around 1500 sqft, but theres 4000 sqft of roof. just too much $. would be great, since i have ceiling speakers, miles of low voltage cable, occupancy sensors in the ceiling, etc etc. sucks digging around insulation for that crap.
also related;
i'm not terribly sensitive to fiberglass, but it does irritate my arms and hands. i've had a 100% success rate when using the most sticky/expensive lint roller i can find.
if any spot is irritated or has that stinging feeling when brushed up against, a lint roller has always fixed me right up after just a sheet or two.