Replies

1. 
   4Lorn1 | Feb 19, 2003 09:50am | #1

   Ages ago I helped insulate the floor of a house in Virginia. Used a hollow kraft paper and foil product. Shipped in rolls about a foot wide opening it causes it to expand into a hollow rectangle, like a very light weight aluminum duct with staple tabs, about 2" deep and wide enough to fill the joist space. It was cut to length easily enough with scissors and stapled up fairly quickly. Not being fiber based there was no itching.

   I was dubious about its effectiveness but after getting half the job done we got up to a cold morning and you could clearly tell where we stopped with bare feet. You could stand in the hall and have one foot warm and the other much cooler. We had pine floors so the difference was pronounced. The stuff worked.

   The only problem is that after using it I can't remember seeing the product again. Maybe someone on this site will have some clue where to find the stuff if you want to use it.

2. 
   rjw | Feb 19, 2003 01:29pm | #2

   Erich,

   There is no definitive answer, but my belief is that you shouldn't; you don't want to recirculate air that has been in the crawl; ley it escape out.

   But read thye info at the Building Science Corp website and talk to local floks to find out what works best in your area.

   _______________________

   "I may have said the same thing before... But my explanation, I am sure, will always be different."  Oscar Wilde

3. 
   jsvenson | Feb 19, 2003 03:03pm | #3

   Erich,

   Nothing wrong with what you have in mind. If this is new construction and you can easily fill the blockwall voids with insulation, do it; also if you can run rigid insulation against the block wall before backfill do that also. Make sure you have a vapor barrier between the earth and the crawlspace. Visqueen held down with two inch scratch coat of concrete or a couple of inches of gravel is good.

   If this is an existing crawlspace, you can drape fiberglass bats down the block wall onto the floor about a foot. Insulate the rim joist area as well. MAKE SURE YOU HAVE A VAPOR BARRIER UNDER THE CRAWLSPACE FLOOR! If it's not there you will have major condensation problems.

   Good luck with your project!

   John Svenson, Builder, Remodeler, NE Ohio (Formerly posted as JRS)

   
   

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   Edited 2/19/2003 7:10:18 AM ET by Svenny

4. 
   DouglasA | Mar 01, 2003 05:36am | #4

   Sealing your crawl space is a bad idea.  What you really want to do is keep the conditioned air in your living spaces.  The barrier is the floor system.  Several others have suggested a number of ways.  I would suggest looking into foam or fiberglas batts between the joist. However, would suggest not using a faced material and if you do be sure to install the facing against the floor sheathing.  Remember the resistance to flow of heat & moisture is similar to the walls and the facing of insulation (vapor barrier) is always to the warm side of the wall.