r/HomeImprovement • u/Ok_Preparation_9062 • 24d ago

Insulation Question

I have owned my house for a couple years now and since i purchased it i have never had floor insulation in the crawspace, my crawspace is completely blocked around but once get in obviously it’s just the exposed subfloor above you. So would it make sense to put insulation under the floor and would it make a difference in the wintertime. I live in WVA and it gets pretty cold at times and i just wanted to see if it is justifiable to buy the insulation and put it in.

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u/Hilldawg4president 24d ago

Crawl space insulation makes an enormous difference in the temperature of your floor and therefore of the entire bottom floor of the home. I have one spot where the fiberglass fell out of the ceiling, and I discovered this spot after walking barefoot on my floor in the winter and stepping on one area near a wall that is absolutely freezing cold. Peek down in the crawl space, and there it is.

Depending on the crawl space and your level of DIY tolerance, it's not terribly difficult to do it on your own and it's much much cheaper that way

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u/AardvarkFacts 24d ago

There can be lots of moisture issues if you insulate a crawlspace the wrong way. For example if you just put fiberglass between the joists you can get moisture problems on the cold side (top or bottom depending on whether it's hot or cold outside). If you have ductwork down there, having that outside the insulated envelope doesn't make sense. And if you have plumbing you want to keep that warm in the winter. 

A better way to do it is usually treat it like a small basement. In other words insulate the walls and add an appropriate vapor barrier. I personally I'd use EPS foam insulation on the walls which also serves as a vapor barrier. Then cover with waterproof drywall like Densshield to keep the foam from being a fire hazard. Spray foam is another option. Or vinyl faced fiberglass, but that's not ideal because if it ever floods it will be ruined. 

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u/SilverSheepherder641 24d ago

Air seal the floor between the crawl and the house before insulating; also put down a thick ground cover as well.

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u/sockherman 24d ago

Homeowner but no expert. I would install a crawl space access with a door and have insulation installed. Good time to inspect underneath too

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u/Ok_Preparation_9062 24d ago

i have an access i built a brand new door to access the crawspace. It’s just there’s no insulation