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  1. #1

    Default Crawl space encapsulation

    Last year we purchased a 1930s vintage bungalow that sits on a shallow, vented, dirt-floor crawl space in a town about 20 miles inland from Myrtle Beach, S.C. It has new siding, roof and the old oil furnace was replaced with a heat pump within the past couple of years. When winter rolled around this year (yes, it does get into the 20s 'round here) we discovered that the crawl space doesn't do much to provide insulation. In fact, not only were the floors cold and the heating bills high, but the dishes stored in deep drawers of the remodeled kitchen would have worked well as chilled plates on a buffet's salad bar. An HVAC company recommended we encapsulate the crawl space, which they said would not only provide insulation but also help keep down moisture -- which is an issue here in the humid coastal south. Does anyone have information on whether this is a worthwhile (As in worth about $4,000-$5,000) approach?

  2. #2
    Join Date
    Feb 2008
    Location
    Nashville, TN
    Posts
    149

    Default Re: Crawl space encapsulation

    I am just up highway 17 from you and I do agree with the idea. and if the comapny will insulate and seal it up for $5,000 that is a deal. The only drawbacks i have ever seen (i am a plumber by trade) is if there is a leak it will be held in like a giant toilet bowl. The insulation underneath the floor with a plastic vapor barrier to hold it in place is a good comprimise. Just seal up the crawl space vents and secure the doors in the winter. in the summer months you want that more open for ventalation. otherwise it will turn into a pair a dirty socks at the bottom of your gym bag. Good luck. Process of elimination.

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
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    4,045

    Default Re: Crawl space encapsulation

    The underside of the floor should definately be well insulated..... closed cell spray foam insulation lends itself perfectly for this application.

  4. #4

    Default Re: Crawl space encapsulation

    Thanks. Are you saying to do the spray insulation in addition to encapsulation or instead of it?

  5. #5
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Crawl space encapsulation

    The critical area is the floor preventing heat loss .... the perimeter walls of the crawl space isn't as critical.

    Here is a related thread : http://advice.thisoldhouse.com/showthread.php?t=3871
    Personally I wouldn't recommend using a plastic vapor barrier covering fiber glass batts .... this will trap moisture.

    Plastic should be placed over the dirt floor of the crawl space.
    Last edited by canuk; 03-04-2008 at 05:31 PM.

  6. #6

    Default Re: Crawl space encapsulation

    I have seen this in Charlotte and it does work - here is another website that may help you
    I don't mean to promote another company I just have 1st hand experience and they were impressive
    www.thefreshaircompanies.com

  7. #7
    Join Date
    Jan 2008
    Posts
    2,203

    Default Re: Crawl space encapsulation

    Upstate in Greenville here, welcome to TOH! If you encapsulate the crawlspace you can probably forego the insulation, which won't add much more help in our climate, and may not be cost-effective unless your floors leak a lot of air. Especially in this part of the world we need to attend to those crawlspace vents twice a year, opening and closing them for our two seasons(winter and summer; the other two normal seasons are too breif here to be called 'seasons'). Do a check or two mid-winter to see if there is excess moisture building in the sealed crawlspace and if there is then open a vent on the side that normally gets the least wind. I would also go with a few more vents than reccommended because summer moisture is more of a problem, even here in the upstate, than the issue of winter sealing and insulation. It will also help moisture abatement to cover the crawlspace with heavy plastic, remembering to leave a foot clearance at all sides and around all pier footings. I would not use fiberglass insulation here with our high moisture levels. After 28+ years of working mostly in SC I personally believe that we need to get as much ventilation to our floors as we can; I've seen a lot more wet rot and mildew than you can shake a stick at and anything that might impede letting the wood breathe will probaby be worse than the problem it solves within a very few years.

    These solutions should work well for you; I've used them in Bluffton, N. Agusta, and Aiken as well as all over the upstate with great and cost-effective results.

    MC

  8. #8
    ChrisJ Guest

    Default Re: Crawl space encapsulation

    It sounds as though you have the answer to the problem - moisture in crawlspaces and basements is more of a problem in the south-east of the country (presumably because of the humidity). Crawl space encapsulation is one of the better ways to prevent the problem, and even though the number you were quoted seems a lot, it isn't considering that it's a "one and done" investment.
    Last edited by Unregistered; 04-16-2008 at 12:43 PM.

  9. #9
    Join Date
    Feb 2008
    Posts
    69

    Smile Re: Crawl space encapsulation

    Quote Originally Posted by ccwriter1432 View Post
    Last year we purchased a 1930s vintage bungalow that sits on a shallow, vented, dirt-floor crawl space in a town about 20 miles inland from Myrtle Beach, S.C. It has new siding, roof and the old oil furnace was replaced with a heat pump within the past couple of years. When winter rolled around this year (yes, it does get into the 20s 'round here) we discovered that the crawl space doesn't do much to provide insulation. In fact, not only were the floors cold and the heating bills high, but the dishes stored in deep drawers of the remodeled kitchen would have worked well as chilled plates on a buffet's salad bar. An HVAC company recommended we encapsulate the crawl space, which they said would not only provide insulation but also help keep down moisture -- which is an issue here in the humid coastal south. Does anyone have information on whether this is a worthwhile (As in worth about $4,000-$5,000) approach?
    Get some estimates for closed cell spray foam insulation, like they use on THO alot. Mike Holmes, on "Holmes on Homes" also recommends this type of insulation. Is there room for an installer to get himself, and spray hose, in this crawl space? Spray foam insulation is great, and needs no vapor barrior. I had a quote for 900 sq ft of closed cell spray foam insulation, for A little over $2000.00. This was for my new woodshop. The spray foam insulation is more costly than fiberglass, but will be much easier to install. You never mentioned the size of this crawl space, but, it will probably not be more that 900 sq ft. Seems like $2000, is much cheaper than $4-5,000.

    Your cold dishes might be the result of cold seeping up from the crawl space, into the walls behind the cupboards. Using spray foam underneath will seal all those leaking spots.

    Aren't old houses lots of fun???

    Best of luck with your project.

  10. #10
    Jacques Guest

    Default Re: Crawl space encapsulation

    A good company to contact for Crawl space encapsulation is Basement Systems. They give free estimates on crawl space encapsulation and should have some advice as well. Their product- CleanSpace - is the first patented crawl space vapor barrier in existence and Basement Systems is the world's largest basement and crawl space waterproofing company.

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