Crawl space encapsulation

Jody Hawk

Senior Member
Has anyone had their crawl space encapsulated where the crawl space is basically sealed off from the outside elements and does away with moisture/humidity issues. Just wondering about how much this costs?
 

naildrvr

Senior Member
Don't do it!!! I've seen too many moisture issues from encapsulation where you have to run a dehumidifier 24/7. I think it's a waste of money. Termites like moisture!
 

southernman13

Senior Member
We’re enclosing part of a pole barn now. It’s got a crawl space. I was going to check into having the underside of the floor sprayed with foam insulation. Also plan on closing it in from the elements but wasn’t necessarily trying to make it water tight. I’m thinking cross ventilation is good for it. At least some. Ian there a downside of spraying foam on underside of floor?
 

naildrvr

Senior Member
I like having cross ventilation in a crawlspace. I also use R-19 Batts between the floor joists. If I'm not mistaken, the energy loss through the floor is only 8-10% and if you have carpet and padding then it's not that much. The foam can be sprayed to the underside of the subfloor, but it's more expensive and I don't see it being a money saving move.
 

southernman13

Senior Member
Tenfo thanks I figured it wouldn’t make a huge difference but I like the way it seals the whole thing. Or the idea of it sealing it. I’ve never had dealings with it. Do you cover the bottom after you install insulation? If not what keeps critters from tearing into it. Thanks
 

naildrvr

Senior Member
You can use chicken wire to keep it from being pulled down by critters or underpin the barn with vinyl like a trailer house.
 

southernman13

Senior Member
Can’t get nothin past me hehehehe. Probably going with metal panels for siding. Have you built like this before? Was thinking of installing it over 7/16 osb for added protection, stability and insulation. Sorry for all the questions. Thanks again and didn’t mean to derail thread
 

naildrvr

Senior Member
Don't screw the metal straight to the osb. The screws will eventually back out. I've used pine 1x4's for stripping to screw the metal to. Some say not to use 1x4, but I've never had a problem as long as they're pine. They hold screws good. I even have part of my house roof stripped with pine 1x4's and haven't had a problem.
 

1gr8bldr

Senior Member
Years ago, the inspections required x number of ventilation per square foot of crawl. This was a mess because some houses had vents 2 feet apart due to situations like a garage on one side which gave no potential of vents in that space. They eventually lightened up on that being that 100 vents did not give cross venting if one side or more was blocked. However, encapsulated if used in conjunction with a well drained dehumidifyer works well. I know people using those lowes sells for $200. A professional grade can be bought for about $1200. The driving reason behind this is that as hot air enters your cool crawl space, it condensates. The water you see come out of your vehicles or a window unit air conditioner is the same. I have been under houses and it be soaking wet, and the house be on top of a hill. And if any exposed metal is not insulated.... it will be as wet as if you painted it in water. This is why home inspectors make every metal duct be insulated because it will cause rot to anything close. Automatic vents..... I have them, but wish I did not. If they closed for humid days then I would not have a problem with them. But closing because of cold is not the only reason to close them. Encapsulated is expensive. However, in my experience, I have never seen a reason against it. But have seen reason after reason to get it, if you have the dollars to spend. It is best to spread blue screenings under the envelope so that future crawling around will not cut the product from the underside on a rock. Ventilation is not the answer. [for the original posters situation, not the pole barn encloser/foam.] Most people don't go under their houses so they don't even know. But go under and look this summer when it gets hot and humid. You will wonder how it has not already rotted away. But this is referring to hot weather only. It does not do this in the winter, fall or spring
 

westcobbdog

Senior Member
Has anyone had their crawl space encapsulated where the crawl space is basically sealed off from the outside elements and does away with moisture/humidity issues. Just wondering about how much this costs?

Aqua Guard has a good product but pricey. Took a continuing ed class they taught a few years ago. Prices seemed to start around $2500 for apprx 2k sq ft ranch. It is an effective system. Certainly there are cheaper methods that are also less effective, imo.
 

Mossy78

Senior Member
Don't screw the metal straight to the osb. The screws will eventually back out. I've used pine 1x4's for stripping to screw the metal to. Some say not to use 1x4, but I've never had a problem as long as they're pine. They hold screws good. I even have part of my house roof stripped with pine 1x4's and haven't had a problem.

I'm one of those guys who says don't use 1x4's.
Had to replace a few metal roofs other guys installed with 1x4's.
Over time, that 1x4 WILL crack and the screws WILL back out, I always use a 2x4.
Also, since the OP stated he was going to underpin the crawlspace, treated lumber would be best, and a wet 1x4 will split even faster, jmho.
 

Duff

Senior Member
Jody,

I have one bedroom over a crawl space (rest of the house is over basement). I had a lot of trouble with temps in the room. The room has everything against it. High ceilings, over crawl space, furthest from HVAC unit, very large window, north side of house, hardly any sun.

Anyway, I covered the dirt with 15 mil poly and I have a friend in the insulation business and he spray foamed the entire crawl space for me--even down onto the poly.

This didn't completely solve my temp trouble, but it helped tremendously. I was worried about moisture but it has been as dry as a bone for 2 years now.
(I told him not to spray the vents just in case. I covered them with 1 1/2" blue board to insulate them, but have never uncovered since it was sprayed)

Sorry, I can't help with price. He did it as a trade for some work I did on his house.
 

Crakajak

Daily Driveler News Team
I like having cross ventilation in a crawlspace. I also use R-19 Batts between the floor joists. If I'm not mistaken, the energy loss through the floor is only 8-10% and if you have carpet and padding then it's not that much. The foam can be sprayed to the underside of the subfloor, but it's more expensive and I don't see it being a money saving move.

Also...IF you ever have to replace subfloor or joists it will be a very expensive project.Penatrations for plumbing would be an issue also if a leak happens.
Adding electric runs would be effected also.
I agree its not worth spraying.
I would rather fill the crawlspace block with concrete and caulk around the exterior between the block and the sill.
 

OmenHonkey

I Want Fancy Words TOO !
My new home is encapsulated and I have enjoyed the benefits from it so far. I see no reason not to do it. I live in South Ga so we have very high humidity during the summer. This will be my first summer coming up and i'm curious how that will be.
 

jiminbogart

TCU Go Frawgs !
Has anyone had their crawl space encapsulated where the crawl space is basically sealed off from the outside elements and does away with moisture/humidity issues. Just wondering about how much this costs?

The last one we did was about a year ago and it was $2,620 including plastic on the ground.

Crawl was 1,550 square feet of floor. $460 for 6 mil poly on the ground and $2,160 for the closed cell foam.

You can do the plastic yourself if you are so inclined.

I have four coming up in a couple months.

I use Keith Porter Insulation(he has done 800-900 houses for us over the years, only 2 foam jobs though).
 
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