under-floor insulation


  #1  
Old 11-08-00, 04:11 PM
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Hi, I live in north Texas (zone 7B to you gardeners) in a 61-year-old house. I am wondering whether it would be effective to add insulation under my floors. We are on pier and beam with a 2-foot crawlspace. The floors are all wood over subflooring (hardwood up front, soft in the bedrooms). We use carpets in the winter, but I wonder whether adding rolled insulation between the joists would be cost-effective or a messy waste of time for someone who waits until she really MUST before she turns on the heat or a.c. (I love "real" air). Thank you!
 
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Old 11-08-00, 05:34 PM
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Heat rises. Because of that, make sure you have more than the minimum required attic insulation for your area. One call to your bldg. dept. will tell you what the minimum is. That will give you the biggest bang for your buck. Having six inches more attic insulation than what the minimum is will make a noticable difference on your utility bills.

Next, look at your walls and windows. If you have 2X4 walls, make sure you have R-13 insulation there. If they are 2X6 walls, then you need R-19 insulation in them. Your windows should be dual pane, with clad or vinyl frames, with at least 1/2" of space between the panes of glass. Upgrading your walls will give the next biggest bang for your buck.

Finally, after the attic and walls have been addressed, insulate the floors. Use as much insulation as will fit between the beams. If they are 4X6's, use R-19; If they are 4X8's, use R-25; etc. This is the area that will have the smallest bang for buck you spend on it. You will eventually recoup the money in the form of lowerer utility bills, but it will take the longest of the 3 areas I mentioned (attic, walls, and floor).
 
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Old 11-10-00, 04:22 PM
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since you asked only about under-floor I will assume that the rest of your house is all right.Under most conditions insulating under the floor does not give a very good return, but your home is not most conditions.You lose an unreasonable amount of heat through this crawl space. insulate between the floor joists with rolls or batts(unfaced)using wire insulation supports.Finish by covering the ground or floor of the crawl space with 5mil poly to keep the moisture from reaching the insulation. (Wet insulation doesn't work!)
GOOD LUCK!
 
 

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