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Mike Carvelli Posted: Jul 24, 2015 05:55 PM	Crawlspace in MN I have a crawlspace in Minnesota with no utilities, venting, anything other than coax cable in it. The crawlspace is under the living room with a small wall, 2 ft. high, shared with the kitchen. From the inside the living room is raised 2' from the slab on grade kitchen. The question is closed or open cell on the underside of the living room floor and stub wall? Local contractors conflict on their advice. Some say closed cell will trap moisture in the hardwood floor and may cause cupping and splitting so use open cell. Others say open cell will hold moisture and cause rotting of the floor and joists so use closed cell. The crawlspace is at grade, with the living room floor being 2' above grade. The crawlspace doesn't get wet, has poly covering the bottom and sealed to the walls, and is lightly vented to the outside. There is no entrance from the inside.
Tony Beehner Posted: Sep 01, 2015 07:15 PM	Hi Mike, If you do not use a moisture barrier between the heated floor and foam, you need to use closed cell foam. Moisture (condensation) is always generated from heat when heat meets cold. Also you must not let any foam come in contact with the ground. Termites will tunnel through the foam and find their way to your wood.

Author

Comments

Mike Carvelli

Posted: Jul 24, 2015 05:55 PM

Crawlspace in MN

I have a crawlspace in Minnesota with no utilities, venting, anything other than coax cable in it. The crawlspace is under the living room with a small wall, 2 ft. high, shared with the kitchen. From the inside the living room is raised 2' from the slab on grade kitchen. The question is closed or open cell on the underside of the living room floor and stub wall? Local contractors conflict on their advice. Some say closed cell will trap moisture in the hardwood floor and may cause cupping and splitting so use open cell. Others say open cell will hold moisture and cause rotting of the floor and joists so use closed cell. The crawlspace is at grade, with the living room floor being 2' above grade. The crawlspace doesn't get wet, has poly covering the bottom and sealed to the walls, and is lightly vented to the outside. There is no entrance from the inside.

Tony Beehner

Posted: Sep 01, 2015 07:15 PM

Hi Mike,

If you do not use a moisture barrier between the heated floor and foam, you need to use closed cell foam. Moisture (condensation) is always generated from heat when heat meets cold. Also you must not let any foam come in contact with the ground. Termites will tunnel through the foam and find their way to your wood.

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