# Warm board or similar over concrete?



## goosegunner (Nov 23, 2011)

Is there a product that you can ad floor heat over a concrete basement floor?

My lower finished basement has its own zone forced air heat so I can control temp pretty well but I am thinking of future additions to system to maximize use of storage.

The concrete does not have foam under it so maybe floor heat is not an option?

gg


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## Frozen Canuck (Nov 23, 2011)

In this instance Goose you would be throwing your btu's & money/sweat away. A slab without adequate/any insul under & around perimeter is going to radiate a ton of btu's to the ground under it & whatever it is exposed to on the perimeter. if you really want warm floors your best option is insualate the floor first with foam sheets high density of course, minimum 1" thick, tape all seams, then warmboard or other product, that allows you to run tubing, hr (hotrod) has posted some of these in the past with thermal images to show performance, then floor covering, tile with a decoupling membrane or laminate would be my first two preferences.

This will be a high cost option though. 

If you are just looking to ditch the forced air in favor of radiant then I would say some nice thin (euro) panel rads maybe a better & for sure a cheaper option, heaterman has posted a few as well as hr.

Hope this helps Goose.


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## bpirger (Nov 23, 2011)

I was going to say the same thing....insulation, then warmboard or other.  Would there be a problem with the warmboard on top of the foam?  It doesn't seem very "firm", I wonder if type would be a problem.  Maybe not.  It would be very expensive to put down the foam, then tubing, then gypcrete or gasp, more concrete.


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## goosegunner (Nov 23, 2011)

Ok thanks, I thought that would be the case for the concrete floors. I don't really need to dump the forced air, more like add to the system in stages to get the best system. Panel radiators would work too.

What about over OSB floors on the second floor, do you need insulation under the floor space if you use any of the grooved board installs?

gg


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## bpirger (Nov 23, 2011)

I think the answer to that is yes....you always want to insulate on the side you don't want the heat to go.  So in this case, below the floor in the joists....


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## velvetfoot (Nov 23, 2011)

Wouldn't it depend on how much headroom you have to work with in the basement?
You still might want to insulate the floor anyway.


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## Frozen Canuck (Nov 23, 2011)

OK Goose; for the second floor you would not need to add insulation on the floor before applying warm board or other product. You just need to insulate the floor joist perimeter as that is where the opportunity to radiate heat to the great outdoors exists. You probably have that done already.

Really when you think of it you would only be adding the cost of foam for the basement to do both floors in a warm board product. Same thing I am considering BTW as I like warm floors, so does my boss (wife). When she gets tired of the floors upstairs that will be my opportunity to get the warm board & tubing in place, then the new floors she wants. Just forces me to plan more & have my products on hand so we both are happy with finished product & the floor is not open for  longer than needed.

Hope this helps.


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## goosegunner (Nov 23, 2011)

Frozen Canuck said:
			
		

> OK Goose; for the second floor you would not need to add insulation on the floor before applying warm board or other product. You just need to insulate the floor joist perimeter as that is where the opportunity to radiate heat to the great outdoors exists. You probably have that done already.
> 
> Really when you think of it you would only be adding the cost of foam for the basement to do both floors in a warm board product. Same thing I am considering BTW as I like warm floors, so does my boss (wife). When she gets tired of the floors upstairs that will be my opportunity to get the warm board & tubing in place, then the new floors she wants. Just forces me to plan more & have my products on hand so we both are happy with finished product & the floor is not open for  longer than needed.
> 
> Hope this helps.



I should have actually said first floor. The box sill is insulated, I do not have access to most of my basement ceiling because it is all finished with drywall.


As far as adding foam to the basement floor. I don't think that would work too well. Wouldn't that throw off the rise on your bottom stair?  I would have to strip all my base and reset my doors. I do have the header height to raise doors but man, my wife would probably have me committed. Sounds like Panel Rads would avoid a lot of trouble for me.

gg


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## rkusek (Mar 22, 2012)

Bringing this one back to life. I was wondering if anyone had considered the Roth panels directly on uninsulated concrete basement floor since that wasn't mentioned. Unlike warmboard it appears to be a 1" piece of extruded foam like pink or blue board except it's white. http://www.roth-usa.com/products_radiant_panelsystem.cfm.   The 1" panel has grooves in the insulation and covered with a sheet of aluminum that fits in the grooves with channels for the pex to snap into.  There is no OSB or plywood from what I can see.  At $8 a sq. ft. I don't see how it could be justified but it sure seems I could make something very similar myself for about $1 sq ft.  1" high density pink board with 1/2" channels cut on table saw with a dado blade and either homemade or purchased aluminum transfer plates bonded to the pinkboard.  The Roth panel allows for either 6" or 12" spacing but a homemade job could just as easily make it 8" which would also come out evenly (6 channels) on a 4x8 sheet.  I'm not sure how difficult it would be to form the correct channels  with a flat sheet of aluminum but I would think one could buy the 2x4 1/2" pex aluminum ones for about $2.40 apiece (or about 60 cents sq ft.).  The gaps in between the plates could be covered with some of the rolled aluminum like used on roofing.  If you wanted to avoid wasting that pinkboard cutting a 1/2 channel, I also think it would work to use 3/4" pinkboard, with 1/2" plywood or OSB between the pex laying on top of the pinkboard.  Use construction adhesive to glue the pinkboard to the concrete floor and also to glue the wood to the pinkboard.  Secure the aluminum and transfer plates to the wood and it seems you would have something very similar to a Roth panel maybe even better.  The headroom in this case would be only 1 1/4" if using carpet or wood laminate, tile would add another 1/2" for the backer board.  3/8" tubing would have less headroom but more work I would think.  The Roth panels say their 3/4" (3/8" pex) is R 3.7 and 1" (1/2"pex) is R 4.5.  Does anyone have experience with this or know why it won't work?  Since the Roth website advertises as such I would think it would be viable and allow for quick response (no thermal mass), no noise, and utilize low water temps because of all that aluminum next to the floor surface.  Any thoughts?


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## mikefrommaine (Mar 22, 2012)

Jlc had an article which used this method. But they used wedi board and mortar to fill the gaps. 

Getting foam to adhere well to the concrete seems  like the biggest obstacle to me. Maybe screws through the plywood into the concrete would lock everything down.


http://www.hansoncarlen.com/upload/pdf/hanson_jlc_02_2012-secured.pdf


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## rkusek (Mar 23, 2012)

Never heard of Wedi board but I see it is specialty backer board insulated underneath and waterproof  for bathroom.  I think I could justify the time, labor,and cost of the 2nd method I talked about.  3/4 pink, 1/2" pex, 1/2 plywood or OSB strips between the pex, either homemade or purchased aluminum radiant plates on top of the wood.  If I buy the plates, I would still cover the rest of the wood with aluminum.  The ends would be the only challege and even that should be easy with a jigsaw cutting the plywood.  Should be able to secure the plywood to the floor thru the pinkboard with fasteners if the glue would be a problem.  Probably looking at about $1.25 sq ft.  I might even go with 12" spacing on the pex since we still have the forced air to supplement heat.


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## 711mhw (Mar 24, 2012)

Check out another forum http://www.greenbuildingtalk.com/Forums/tabid/53/afv/topicsview/aff/12/Default.aspx
There are some pro's over there and lots of experienced folks on that topic.


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## dogwood (Mar 25, 2012)

Nice link to GreenBuildingTalk, 711mhw. Right up my alley. I cast my vote for panel radiators. Why make massive changes and create so much work and cost for yourself when panel rads should give you as good or better heat, and will absolutely maximize your storage. Just sayin'.

Mike


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## rkusek (Mar 26, 2012)

The basement is unfinished except for 2 outer framed walls and the floor is bare uninsulated concrete so I need to do something with it anyway.  Wife won't go for the panel rads and that would cost about the same the last time I checked.  The forced air does a decent job now so I might be money ahead to just finish the basement and add a couple registers.  This would be mainly in the new bedroom and new bathroom.  I suppose carpet with a thick pad or tile with a backer board would provide enough of a thermal break against the concrete anyway.  It's probably best to keep it simple.


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