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  1. #1
    Join Date
    Oct 2007
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    Default COLD downstairs floors! Other insulation questions too

    Hi all,

    We just had our first bout with cold weather here in SE VA and it may be old age on my part but it seems like my floors are colder than they were last year! My house is a 1942 Cape Cod on a crawl space. I've been under the house and there is insulation between the floor joists but it was in sad shape. Should I install new fiberglass batt insulation, foam or what? I'd also like to know if I should block off the foundation vents in the winter. I *hate* for my feet to be cold!

    The other insulation question I have is, what is the general cost for injected foam (closed cell?) insulation into the exterior walls? If it helps any, my house is 1500sf roughly. Thanks for any help or information!

    Jeff

  2. #2
    Join Date
    Sep 2007
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    Long Island, NY
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    269

    Default Re: COLD downstairs floors! Other insulation questions too

    First of all those vents should absolutly be shut or blocked off in the winter.
    fiberglass insulation should be more than effective as long as its installed properlly and IN GOOD SHAPE.
    Do yourself a favor and install some good fiberglass insulation and remember the paper faces the living space.
    You can buy wires that just bend into place under the insul to hold it up. No tools required! Cept' your knife to cut the batts.
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  3. #3
    Join Date
    Oct 2007
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    SouthEastern VA
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    Default Re: COLD downstairs floors! Other insulation questions too

    Thanks for the input Andybuildz. How about the injected foam insulation in the exterior walls? Is closed-cell better than open-cell? I know that I saw them install one form or the other on the East Boston house but I don't recall which one.

  4. #4
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    Sep 2007
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    Long Island, NY
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    Default Re: COLD downstairs floors! Other insulation questions too

    Quote Originally Posted by Warped View Post
    Thanks for the input Andybuildz. How about the injected foam insulation in the exterior walls? Is closed-cell better than open-cell? I know that I saw them install one form or the other on the East Boston house but I don't recall which one.
    In a crawl space I'd used closed cell foam. Its less likely to absorb mositure plus I believe the R value is much better BUT its a lot more expensive. If I were you I'd weigh out the costs between closed cell and fiberglass and determine whats most cost effective for you in the long haul. There's nothing wrong with fiberglass if its installed right. If you plan on spending mucho years in the house then you may want to consider the closed cell foam.
    Your call.
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  5. #5
    Join Date
    Aug 2007
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    The Great White North
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    Default Re: COLD downstairs floors! Other insulation questions too

    Quote Originally Posted by andybuildz View Post
    In a crawl space I'd used closed cell foam. Its less likely to absorb mositure plus I believe the R value is much better BUT its a lot more expensive. If I were you I'd weigh out the costs between closed cell and fiberglass and determine whats most cost effective for you in the long haul. There's nothing wrong with fiberglass if its installed right. If you plan on spending mucho years in the house then you may want to consider the closed cell foam.
    Your call.
    andy ... good to see you back .

    To add to andy's helpful post ... fiberglass batts have couple of issues in an open air environment.

    1 - moisture that is absorbed into the batts will decrease the performance of fiberglass

    2 - moving air will decrease performance of fiberglass batts

    In the crawl space you can minimize those issues with covering the underside of the fiberglass batts with Tyvek or similar house wrap and not plastic. The house wrap will help reduce moving air from contacting the batts and still allow them to breath helping evacuate moisture.

  6. #6
    Join Date
    Nov 2007
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    35

    Default Re: COLD downstairs floors! Other insulation questions too

    The whole thinking on crawlspaces has been revised. Originally, dirt floor, sometimes gravel, with vents to relieve moisture buildup from the earth. Now it's done a 180: 6 mil poly sheeting over the earth with gravel over it to hold & protect it, insulation up the sidewalls and the vents blocked off completely, everything sealed to keep moisture out & away. Also joist bays completely filled with new clean dry f/glas insulation, also with 6 mil poly below as airflow/vapor barrier, although that gets interesting around pipes etc. Rigid foam used like drywall would be be easier to handle & deal with in general. That should stay nice & toasty all winter from then on.

    There are contractors specializing in this procedure, or of course it's not rocket science, you can DIY, it's just a pain in everything you can feel pain in. (I hate crawlspaces.)

    Consider that when the old insulation that is "in bad shape" is removed would be a ****en opportunity to retrofit a PEX hydronic under-subfloor system to supplement the existing heat. Mmmm...!

    As to blown-in insulation for the exterior walls, the only one who can tell you how much is that contractor. My understanding is, the blown stuff, usually treated cellulose that resembles a foot of new-fallen gray snow when done, is usually put into attics and liquid foam is usually used in walls, pumped in through holes in each stud bay; after which someone has to patch & paint every 16"-- probably you.

    1942? You may already have a little insulation...? Possibly R-9. Consider if you re-side the exterior, it's common but by no means universal practice to underlay with rigid foam -- its R value is misleading: 1/2" is rated as merely R3 to R4 but done right the effect on heat loss & airflow is amazing!

    One giant energy hole on older houses is the windows, which is why the replacement window racket is such an easy sell. If yours are still original, before doing anything with them go out RIGHT NOW and get the January 2008 Fine Homebuilding, which has an excellent article titled "New Life for Old Double-Hung Windows."

  7. #7
    Join Date
    Oct 2007
    Location
    SouthEastern VA
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    33

    Default Re: COLD downstairs floors! Other insulation questions too

    Thanks for the responses Canuk and C Ed Wright. I'm going to try to tackle this with the help of a friend this coming weekend. I would like to a little further clarification if you don't mind though.


    1: When you said, "Fill the joist bays" with fiberglass batts, do you mean to put multiple layers from the subfloor down to the bottom of the joist or do the batts come in some standard thickness that will effectively fill it up? Should I use the metal rod hangers or is there a better method?

    2: If I should use multiple layers, I assume that the first should have backing on it that would actually contact the subfloor as andybuildz said in his response to my post and the second layer without backing?

    3: Which is better, Tyvek or 6 mil plastic sheeting?

    4: Can I put rigid styrofoam into each bay below the fiberglass batts and get a better R value?

    5: I would LOVE a hydronic system in the downstairs but I don't see how it could be done with a crawlspace house with a forced air HVAC system (no boiler) and electric water heater (located in the DETACHED (wth?) garage. Is there a way to have one using a circulator pump and a tankless water heater?

    Thanks again for your help gentlemen!

    Jeff

  8. #8
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    Aug 2007
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    Default Re: COLD downstairs floors! Other insulation questions too

    2- yes

    3 - Tyvek or similar house wrap and not plastic. The 6mil plastic will trap moisture inside the insulation.

    4 - once you have fill the joist bays with bat insulation you can attach rigid foam sheets to the under side of the joists. This will provide a thermo break to the joists themselves which will increase the insulating properties. You can then eliminate the need for the house wrap.

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