crawlspace insulation

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  #1  
Old 09-26-05, 07:06 AM
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crawlspace insulation

What is the proper insulation to install in a crawlspace? Also, what side does the paper face when the insulation is installed?

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  #2  
Old 09-26-05, 07:22 AM
Ed Imeduc's Avatar
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Go to http://aboutsavingheat.com/crawlspace.html
be sure and read it all.
A 6 mil poly on the ground, insulation on the walls and up on the sill plate in each joist space all around the home

ED
 
  #3  
Old 10-02-05, 08:03 PM
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I'd go no less than 8 mil polypropylene vapor retarder in crawl space. You can use rigid foam insulation on the walls and batts with vapor retarder facing heated floor above between joists.
 
  #4  
Old 10-03-05, 04:36 PM
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Dont put any insulation up in the floor joist at all .

ED
 
  #5  
Old 10-03-05, 06:29 PM
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crawlspace insulation

Omitting insulation between the joist may be fine in warm climates where the soil temperatures are high, but it leads to an uncomfortable room above the crawl space in a cold climate.

The soil under a house is a huge heat sink and it will cause the crawl space temperatures to be in the 40's or 50's at best in the winter unless you attempt to heat the crawl space ($$$$). It is just like not insulating one wall of a home in a slightly more moderate climate. - This is if you neglect the air infiltration from around and through the vents.

The poly does a wonderful job of minimizing moisture, but has no effect on the temperature.

The cool air in the crawl space quickly cools the floor above and can actually raise heating bills by forcing people to bump up the thermostat.

If you do not insulate between joists now you will in the future.

Dick
 
  #6  
Old 10-04-05, 08:51 AM
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If you check in any and all test homes it cost less to heat a home. That the crawl space is sealed up and has the insulation on the walls and not up in the joist space. With outlets for heat down there.Some cites up north have just changed code to seal up the crawl space and put insulation on the walls.

Years back ran into a home that had no duct work at all in the crawl space . Just blowed the hot air down in it. Had registers cut into the floor all around the home . Worked just fine. Asked around 6 other homes just like this one had duct work and all and their fuel bills where way higher than this home that had the sealed up crawl space. Now this is up in Missouri and I have seen it get down to -10F

ED My .02 cents
 

Last edited by Ed Imeduc; 10-04-05 at 09:04 AM.
  #7  
Old 10-04-05, 11:29 AM
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crawlspace insulation

As I said, omitting insulation in COLD climates can lead to an uncomfortable room above the partially insulated crawl space. A day or two with a minimum of -10 and an average temperature of 15 for the day is not cold - it is moderate.

In a cold climate you would never build a slab on grade home without insulation under the slab. The folly of only a thermal barrier (vertical or sloping outward) has been abondoned. A case in point - I owned a lake home (-45 minimum and -20 common with R30 exterior walls and 3" of rigid down 54 inches and no insulation under the slab. The interior was heated to 65 all winter. In May, when the heat was turned off the slab was 65 degrees. By June, the floor was cool enough (59 degrees) to cause condensation.

Traditional insulation methods are based on the classic static condition design. Dynamic methods and testing point out when you can use the benefits of mass and when you must isolate the structure from the massive heat sink of the earth. Each location has its own thermal rollercoaster.

Without heating the crawl space area, the soil temperarure will be cool due to the underlying natural temperatures. This will cause the floor to be cold and the temperature would be bumped up to make up for this and the rest of the house can be too warm. Heating the crawl space is just as expensive.

Some techniques work in some climates, but they are not the best solution in all climates. Not insulating the joist area is just like not totally insulating a home completely. The question is how much heat do you want to lose to the soil.

Dick
 
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