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  1. #1
    Join Date
    Aug 2009
    Posts
    54

    Clean Space encapsulation versus venting

    Does anyone have (or know anyone who has) a crawlspace that has been equipped with the 'Clean Space' encapsulation system? What are your thoughts and experiences with this approach? http://www.all-dry.com/crawl-space.php

    Here's my issues: I had a new heatpump/ac system and duct work installed a little over a week ago (the indoor unit is in the 1150 ft2 crawlspace), and it is much more efficient than the old system....the supply/plenum end is sweating profusely, as well as the outside foil of the duct insulation. I can smell slight musty odor when I enter the side entrance (the dampest end of the house's crawlspace).

    It's been raining a lot this past week, and the RH in the crawlspace is in the mid 90's%....even during drier weather, and using a vent fan, I've never been able to get the RH under the low 80's%. During a dry day, the vent fan would pull the RH down a few%, but if left to run past 6:00pm the RH would go back up. The house has had a poly (6mil) moisture barrier down for a long time, although it's far from being sealed....there is some exposed earth in a few places, but it's mostly covered. However, the crawlspace has ALWAYS had that dank, musty smell to it. There is no standing water that I've seen, except for now with a puddle on the poly barrier under the plenum from the colder air of the new system.

    Here is what I'm trying to decide on:

    1) Putting down a new 6mil barrier, and installing a Santa Fe dehumidifier. Possibly blocking off the vents to cut on humid air coming back in, although this would be far from actually sealing off the crawlspace.
    2) Contracting the local Clean Space guys to encapsulate the crawlspace. The estimator said he didn't think I would even need a dehumidifier with the Clean Space system installed (they also sell their dehumidifier which is a version of the Santa Fe Advance). This option has a lot of promising claims and sounds very good to me, and the cost isn't really *that* bad if I don't have to buy a dehumidifier. It's hard to shake the old wisdom of needing to have ventilation in the crawlspace though.

    Sorry so long, but it's hard to find any reviews or first-hand customer opinions online....lots of hits for the companies that install it though.

    Help?
    Last edited by DaveH2; 09-26-2009 at 09:30 AM. Reason: Edited to add link of product

  2. #2
    Join Date
    Mar 2005
    Posts
    997
    Those system are very nice but a 6mil VP installed correctly will serve just as good. I would not get the dehumidifier up front on ether job. You may not need it. Venting the crawl will just dump humid air into a cool crawlspace. Look to pay about 4 times the cost for the crawlspace systems.

  3. #3
    Join Date
    Dec 2002
    Location
    in a house, Appomattox, Va.
    Posts
    3,197
    If you live in the South or around gulf, can't dry a wet crawl w/ wet air. only works in cold weather up north.
    I put down plastic in mine, sealed vents and put in portable dehum. keeps down to 55% easy down there. Also, the crawl walls have less heat loss than if I insulated the entire floor of house.

    Seen a few of the encapsulated crawls. very nice.
    Col 3:23


    questions asked, answers received, ignorance abated

  4. #4
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,065
    Plastic down, close the vents the best you can, and install a Santa Fe Compact at a minimum. That will get 50%RH and help keep the mainfloor dry also. Regars TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  5. #5
    Join Date
    Aug 2009
    Posts
    54
    Quote Originally Posted by drk View Post
    Those system are very nice but a 6mil VP installed correctly will serve just as good. I would not get the dehumidifier up front on ether job. You may not need it. Venting the crawl will just dump humid air into a cool crawlspace. Look to pay about 4 times the cost for the crawlspace systems.
    drk, thanks. I'm in SC, so I expect I'll HAVE to install a dehumidifier if I just put down plastic. I've had plastic (it's a bit torn up, but mostly there) down for a long time and have always had high humidity issues....I just didn't realize how bad it really was until recently when I put a hygrometer down there.

    A dehumidifier and 6 mil poly will run about half of what the Clean Space encapsulation will run.

  6. #6
    Join Date
    Aug 2009
    Posts
    54
    Quote Originally Posted by billygoat22 View Post
    If you live in the South or around gulf, can't dry a wet crawl w/ wet air. only works in cold weather up north.
    I put down plastic in mine, sealed vents and put in portable dehum. keeps down to 55% easy down there. Also, the crawl walls have less heat loss than if I insulated the entire floor of house.

    Seen a few of the encapsulated crawls. very nice.
    Thanks billygoat.

    I live in upstate SC, so it's quite humid like where you're at. A few questions on what you said:

    - How did you put down the poly...is it on the 'floor' of the crawlspace only, or did you run it up part way on the walls?

    - What does the crawlspace temperature get down to in the winter time where you're at, with the vents being sealed off?

    - Are you saying that you don't have any insulation under the floors?

  7. #7
    Join Date
    Aug 2009
    Posts
    54
    Thanks for your replies TB (both here and other threads).

    How do you suggest doing the plastic barrier....crawlspace floor only, or up the sides as well?

    I really like the specs on the Santa Fe Advance, but I'm a little hesitant in regards to the low-end temp/operating spec. If it gets down to 20 degF outdoors, do you think the crawlspace temp be high enough (with sealed vents) to support the use of the SF Advance?

    The AH and duct work are under the house and should contribute to keeping the temp up a bit, I just don't know how much.

  8. #8
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,065
    Evaporation of moisture from the earth and moisture in the outside air are the largest sources of moisture. The masonary walls are a very small source moisture. Covering earth and closing vents stops 90% moisture. Wind will still introduce some fresh air. Addition sealing and covering up walls reduces the dehu load some.
    The When the outdoor dew point drops below 50^F, dehumidification is no longer needed. Therefore the dehu does not operate when the crawlspace is cold. The Santa Fes are designed to operate in the crawlspace/basement conditions. Keeping the crawl dry also helps the humidity levels in the home.
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  9. #9
    Join Date
    Nov 2008
    Location
    Houston, TX
    Posts
    77
    I'm a big fan of sealed and conditioned crawl spaces. I did the poly on the ground, styrofoam insulation on crawl walls, sealed the vents, and put a Humidex in. This was when I lived up north. Crawl space smell disappeared completely. Interior house humidity went from mid 50's % down to mid 30's %. My dehumidifier was retired since it would never turn on after doing the above.

    In a hotter humid south, I'd do exactly the same as the video here:

  10. #10
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,065
    Quote Originally Posted by Baseboard Gord View Post
    I'm aand put a Humidex in.
    . My dehumidifier was retired since it would never turn on after doing the above.

    In a hotter humid south, I'd do exactly the same as the video here:
    Nice video, but a word of caution about Humidex. This is an exhaust device that exhaust air to the outside. The ideal is that damp air exhausted out of the crawlspace or basement. This works real good as the replacement outside air that infiltrate the home to replace the Humidex exhaust is dry. So a great device for dry climates with low dew points. In the typical green grass climates, exhaust basement/crawlspace means wet air is being sucked in the home to replace the exhaust. This is a big problem during most summer weather. Forget about the exhausting air, use the dehumidifier as the back-up. During windy weather, enough fresh air will infiltrate, that the dehu is needed. Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  11. #11
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    I used a piece of Rubber roofing to cover my crawl space and sealed the perimitter to the base of the foundation, no problems to date and insulated the floor joist above with R-19 my Kitchen satys nice and warm and the crawl space is dry as a bone.

  12. #12
    Join Date
    Nov 2008
    Location
    Houston, TX
    Posts
    77
    I agree with Teddy Bear on the above comments. The Humidex worked great summer and winter in the Pacific Northwest. I wouldn't do that down here in south Texas though.

  13. #13
    Join Date
    Aug 2009
    Posts
    54
    Quote Originally Posted by DanW13 View Post
    I used a piece of Rubber roofing to cover my crawl space and sealed the perimitter to the base of the foundation, no problems to date and insulated the floor joist above with R-19 my Kitchen satys nice and warm and the crawl space is dry as a bone.
    No dehumidifier needed? Whereabouts are you located?

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