Checking cantilevered floor for insulation
kickstarter
| Posted in General Questions on
What’s the best way to check a cantilevered floor for insulation? The floor is a fireplace that sticks out of one of the walls on the first floor of the house. It’s unfinished floor (subfloor). I was thinking about drilling a small hole and inserting an endoscopic camera. Or would a thermal camera be able to pick up a temperature difference if it’s cold outside?
If I did this and there is insulation, can I just use great stuff foam to fill the hole?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
A thermal camera should make it very apparent if there is a lack of insulation in there, and it should make it pretty clear if there are other issues (minimal or leaky insulation). You'll see lots of blue on a cold day if you look at the image from indoors, or red if you look from outdoors.
Bill
Thanks. Is there a miminal temperature differential between indoor and outdoor your would need to pickup any issues?
That depends on the camera, but most should be plenty good enough to show you and big problems. All you need is enough of a differential for the camera to "see" it. If it's a significantly different color from the rest of the structure, then that indicates it's either better or worse in terms of thermal loss/gain, and that's what tells you if the insulation is different or not in comparison to the surrounding areas.
Bill
Thanks. On the inside of the home, the cantilevered floor is reading 20 degrees colder than the rest of the home. Would you drill a small hole into the subfloor there and use an endoscopic camera to check under it?
A borescope will work fine, it's just more "invasive", as the medical people like to say.
I agree with Michael too -- you don't need to insulate the small hole, because the sheathing/cladding you drill through isn't really contributing to the insulating value of the assembly. The use of canned foam for this sort of thing is more out of convenience, it isn't needed for the insulating properties of the foam. If the hole is pretty small, my preference would be for caulk/sealant, silicone (if it'll be exposed to sunlight at all), or polyurethane (if it's more concealed, but silicone is fine in this case too), since the sealant material is going to be more resistant to insect damage than canned foam.
Bill
I agree that a thermal camera would be best, but borescopes are more affordable, if you're not looking for the quality of the insulation, just whether there is any. You don't need to insulate the hole you make for a borescope, but you should patch the surface so it's airtight. If it's not visible, a good quality building tape would be fine.
I've drilled a small hole and then stuck a piece of coat hanger wire in the shape of an L into the hole and spun it around. Insulation feels very different from anything else that would be in a joist bay.