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Heating unvented crawlspace/no insulation

Posted by wianno (My Page) on
Wed, Jan 9, 08 at 12:57

I have a crawlspace that is 18'x25' by 2-3' high. Very low. I plan to have "Cleanspace" encapsulation system installed on the dirt floor and up the walls next week. Foundation is lose stone with a concrete block cap, sill on the blocks. I have recently closed the one vent in the foundation and have been spraying foam insualtion (Great Stuff) between the lose rocks and cracks.

Would it be beneficial to hang a baseboard type radiator (ie slantfin)in the crawlspace if I do not put XPS insulation on the ground under the Vapor Barrier or along the walls? Would I just be wasting money?

Follow-Up Postings:

RE: Heating unvented crawlspace/no insulation

Yes adding heat there is a total waste of money. It would work to keep the floors above warmer but will leak to the outside quuckly. There are way cheaper solutions. How much is this "cleansopace" system going to cost you? You know you can do the exact same thing yourself right? 2 inch XPS against the wall up to the sill, close and seal the vents, 6 mil poly on the floor lapped up the walls. All sealed. I did the exact same thing for a 18x10 crawl under my parents house a few months ago. Did wonders for a long standing problem and was pretty dirt cheap to boot.

RE: Heating unvented crawlspace/no insulation

Heating the crawlspace is a waste of money. Put insulation in the floor joists. Use kraft faced with the kraft face up twoard the heated area. They make stiff metal wires that you push up that holds the insulation in place. Your floor will stay warmer. With the encapsulation system you can shut off the vents and the crawlspace should remain well above freezing. Just insulate all the pipes and you wont have any problems.

RE: Heating unvented crawlspace/no insulation

Insulating the walls is not possible with rigid foam due to the uneveness of the foundation. As mentioned, it is composed of lose rock, think stone wall, and a bad one at that, topped with 1 course of concrete block. There is probably a 4 inch variation.

I actuallty considered doing it myslef with 15 Mil VB from Raven Industries. I even went so far to look into plastic friction type plugs (think automotive trim clips) that I could push into predrilled holes in the concrete block to hold the VB against the wall.

The problem is I have lots of utilities and a sump in the space and need to access it often, with tools. Tools will puncture 6mil poly. Also, I have poly in another crawlspace in my house, and trying to crawl around on it is frustrating as it moves. Since the Cleanspce product is warrantied for 25 years, I can get them to repair it. Plus, the product is white, and will make the space much brighter, and easier to work in.

I already put 2" foam board in between the joists. I did not find it very effective, but then, it was an vented space. Now, it will be a nonvented space.


The following article lends some credence to heating a crawlspace.

Its noted that if insulating the interior, then the rim joists are most important.

Here is a link that might be useful: Heated crawlspace

RE: Heating unvented crawlspace/no insulation

First of all, you did the right thing by great stuffing the open spaces. You will find that sealing off the vents in your crawl space is very beneficial! To answer your question though, I would have to say it would be a waste of money to hang ie slantfin in the crawl space. You said you are going to have your crawl space encapsulated anyways, so you will be fine!

Here is a link that might be useful: Unitedcrawl

RE: Heating unvented crawlspace/no insulation

You can still hang bat insulation on your foundation wall. I would wait until its insulated to see if you need aux heat. My insulated crawlspace stays at a comfortable temperature without added heat.

Here is a link that might be useful: option 3

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