Insulating crawl space


Old 08-13-02, 04:53 PM
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Insulating crawl space

I have a sunroom added to a corner of my cape style house. There are windows on 4 sides. It gets chilly in the winter and I want to do something about it now. There is no basement under the sunroom - there is a crawl space about 3 feet high, dirt floor, and it's damp. There is one small window - that's my only access. I know I need to cover the dirt floor with plastic sheeting. How should I insulate? Should it be the ceiling of the crawl space (underside of sunroom floor), or the foundation walls of the crawlspace which are poured concrete. What type of insulation should I use? Thanks for any help.
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Old 08-14-02, 08:25 AM
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About 20 years ago I developed a crawl space insulation system that I have not found the equal of, yet. It's easy and low cost too.

You must have good drainage, a must. Best to have a sump pump installed . These can be installed on the out side of the house.

Close the air vent and seal.

Check for air spaces to the out side and foam shut.

Install two layers of 4 mil pastic (crossed) over the earth with the bottom layer first going up the side wall and attaching to the side of the bottom plate around the inside perimeter of the wall.

Install a single 48" wide sheet of radiant barrier material to the side of the bottom plate over the 4 mil plastic and let it drape down to the floor. Use either a double foil laminated with a no tear scrim or foil laminater to both sides of a THIN plastic film. The material that is a bubble sheet with aluminum foil is good too, but, it costs too much and the performance is the same as the thiner material.

The crawl space temp will be about the same as the up stairs temp and you will not have any moisture problems.

If there is any fiber type insulation inbetween the joists at the rim board, remove and replace with the RB material. The fiber material is rotting out the board and growing mold.

By doing it this way you also protect your pipes from ever freezing.

If you need any more info let me know.

Thank you for considering my opinion.
Old 08-14-02, 11:53 AM
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Thanks for the advice. It all sounds like something I can manage myself. Does the radiant barrier have a "right" and "wrong" side? If so, which side should face the crawl space? Also, I'm reluctant to seal up the window/storm window. There are hot water heating pipes running under the sunroom floor and I have needed access to them once before for repairs.
Old 08-14-02, 04:23 PM
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Seal the opening with a gasket of some sort. You don't want cold air blowing in. Cut a RB section to act as a curtain that you move when access is necessary but will still cover the opening.

There is no right or wrong side.

If you need more info or samples. let me know.

If you chose to use the RB I know you will very pleased with the results.

It is a fairly easy DIY.
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