EcoRenovator - View Single Post - Is there a thread on crawlspace encapsulation?

Student 07 · 04-12-12, 06:32 PM

Hi,
You're definitely on the right track IMHO. I think crawlspaces are very misunderstood and cause many problems for the homeowner.

Crawlspaceinfo.com has some great information.

When I constructed our house I was required to "encapsulate" our crawlspace. I threw down some black 6mm visqueen and passed inspection. Now it is sagging on the walls, some spots on the floor have torn- I need to do it properly.

I have radiant floor heat in the floor over my crawlspace, so the floor has lots of fiberglass insulation, but fiberglass insulation doesn't stop airflow, odors, moisture etc., I don't have any of these issues, the floor of the crawlspace does have a vapor barrier and there are no open vents, but the floor should be sealed for energy reasons and an ounce of prevention.

My current project is adding rigid insulation below the fiberglass, to add R value and keep the fiberglass from hanging down. When all the rigid insulation is in I plan on using foam to seal it air tight.

Another thing I may do is install Tyvek across the bottom of the joists as an additional measure. I contacted a DOW engineer and she said that would be an excellent application for Tyvek. She explained that basically a floor is just a horizontal wall. IMO the floor cavity should be protected like a wall cavity. I wouldn't want wind and moisture flowing across the back of the sheetrock in my walls, why would I want it on my floor?

The crawlspace is closed off, but air still moves as it is heated and cools down.

I think there would be many benefits to heating the crawlspace. Heat moves to cold, if it is warm in your crawlspace heat is moving from your home though the floors insulation (albeit slowly) into your crawlspace. If your crawlspace is warmer than outdoor it is sucking heat out of your home.

I have been considering ventilating the crawlspace with a heat recovery ventilator/ heat pump. Something like this, but with 110V Genvex Heat Pump and Heat Recovery Ventilation Solutions
The fresh air would take care of any odors; the heat pump would heat the incoming fresh air in winter. In the summer the heat pump would dehumidify the incoming air and provide cool air below your floor which is better than heat in the summer. The unit wouldn't have to be very large, especially in summer. In winter, even a little heat in the crawlspace would decrease the delta T and with lots of insulation, very little heat should get sucked out of your house and into the crawlspace.

Good luck with your’ project. Keep the gap for termite inspection and check out the crawlspaceinfo.com website it has lots of great information.

04-12-12, 06:32 PM	#5
Student 07 Helper EcoRenovator Join Date: Dec 2011 Location: Gresham OR Posts: 35 Thanks: 0 Thanked 3 Times in 3 Posts	Hi, You're definitely on the right track IMHO. I think crawlspaces are very misunderstood and cause many problems for the homeowner. Crawlspaceinfo.com has some great information. When I constructed our house I was required to "encapsulate" our crawlspace. I threw down some black 6mm visqueen and passed inspection. Now it is sagging on the walls, some spots on the floor have torn- I need to do it properly. I have radiant floor heat in the floor over my crawlspace, so the floor has lots of fiberglass insulation, but fiberglass insulation doesn't stop airflow, odors, moisture etc., I don't have any of these issues, the floor of the crawlspace does have a vapor barrier and there are no open vents, but the floor should be sealed for energy reasons and an ounce of prevention. My current project is adding rigid insulation below the fiberglass, to add R value and keep the fiberglass from hanging down. When all the rigid insulation is in I plan on using foam to seal it air tight. Another thing I may do is install Tyvek across the bottom of the joists as an additional measure. I contacted a DOW engineer and she said that would be an excellent application for Tyvek. She explained that basically a floor is just a horizontal wall. IMO the floor cavity should be protected like a wall cavity. I wouldn't want wind and moisture flowing across the back of the sheetrock in my walls, why would I want it on my floor? The crawlspace is closed off, but air still moves as it is heated and cools down. I think there would be many benefits to heating the crawlspace. Heat moves to cold, if it is warm in your crawlspace heat is moving from your home though the floors insulation (albeit slowly) into your crawlspace. If your crawlspace is warmer than outdoor it is sucking heat out of your home. I have been considering ventilating the crawlspace with a heat recovery ventilator/ heat pump. Something like this, but with 110V Genvex Heat Pump and Heat Recovery Ventilation Solutions The fresh air would take care of any odors; the heat pump would heat the incoming fresh air in winter. In the summer the heat pump would dehumidify the incoming air and provide cool air below your floor which is better than heat in the summer. The unit wouldn't have to be very large, especially in summer. In winter, even a little heat in the crawlspace would decrease the delta T and with lots of insulation, very little heat should get sucked out of your house and into the crawlspace. Good luck with your’ project. Keep the gap for termite inspection and check out the crawlspaceinfo.com website it has lots of great information.