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deputy_dog123
Registered Users
Posts:1
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| 02/16/2005 11:51 AM |
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| I am planning on building a new garage and am wanting to use radiant heating in the slab to heat it in the winter time. I was wondering how you insulate the sides of the slab so the insulation is not exposed to the elements and such since it is a slab on grade and the sides are not below the ground? I was wondering if anyone has used the Insul Tarp insulation instead of the standard 2" foam insulation under the slab? And also, can I use just a plain water heater if I am only going to have 1 zone and a closed system? Thanks. |
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gordb
Registered Users
Posts:5
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| 02/17/2005 7:26 AM |
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I have used insultarp and it installs and works well. I am not sure how it works compared to styrofoam though. A regular water may work if your btu requirements are low enough. Your radiant company should be able to supply all that info for you. There are many radiant sites you can go to to see how to insulate stemwalls, etc.
Good Luch,.......Larry |
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OKBlocker
Registered Users
Posts:635
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| 02/18/2005 4:36 AM |
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InsulTarp reflects 97% of the heat upward into the living space where as regular styrofoam board only reflects like 30%.
I would suggest and email to markross@arit.com for your questions on radiant floor heat systems and insulation. |
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Davee
Registered Users
Posts:25
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| 03/16/2005 2:48 PM |
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quote:
Originally posted by deputy_dog123
I am planning on building a new garage and am wanting to use radiant heating in the slab to heat it in the winter time. I was wondering how you insulate the sides of the slab so the insulation is not exposed to the elements and such since it is a slab on grade and the sides are not below the ground? I was wondering if anyone has used the Insul Tarp insulation instead of the standard 2" foam insulation under the slab? And also, can I use just a plain water heater if I am only going to have 1 zone and a closed system? Thanks.
The Legalett airduct in concrete system works well for add ons like this. I heat 1120 sq ft in Northern Ontario using the hot water tank only. It involves gravel styrofoam & concrete floor/ heat storage system. You use small grundfos pump to push water through a coil & a fan moves the heat in the slab . Developed in Sweden 27 years ago . See www.legalett.ca & say Davee sent you |
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Unregistered
Registered Users
Posts:2321
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| 03/16/2005 11:05 PM |
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here's some good text on radiant and insulation http://www.healthyheating.com/blog/
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Davee
Registered Users
Posts:25
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| 04/08/2005 11:00 AM |
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The slab on grade --foundation & radiant heat system has a lot of advantages -- Among them much simplier construction with no digging below frost (if done right!). The slab can handle poor soil conditions also. I went with Swedish system developed over 27 years which uses hot air ducts cast in the concrete. so no freeze up or puncture or pipe failure is possible. I run my walkout basement at about 65F and supplement when needed with a small electric heater because the system is slow to respond to a thermostat change. It is also very slow to lose temperature during power failures.
See the website for more info
www/legalett.ca
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tomgocze
Registered Users
Posts:2
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| 05/24/2006 9:23 PM |
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I have been involved in heating research for a number of years. Also host a radio and TV program on home construction and energy. My co-host is a recently retired Mechanical Engineering professor from the University of Maine.
We regularly get calls about foil faced bubble wrap and foil faced thin flexible foam for use in place of the standard of 2" of Styrofoam for insulating radiant slabs.
Most building materials get a Factory Mutual rating for their insulation values. All foam and fiberglass manufacturers use this service, it is like UL for electrical devices.
Is there any Factory Mutual rating for any foil faced wrap material? I don't think so.
Foil is a radiant barrier, but we are not radiating heat down into the soil underneath a slab, we are conducting the heat away.
If you consider the actual physical rating of the materials that comprise this stuff, they are more like R 1 to 3. What muddies the situation is our perception of the warmth that radiates from our skin when we hold this material reflecting back, if that is warm then it must be good?.
I think the physical separation that 2" of foam offers in segregating the slab from the subgrade is extremely important in marginal sites.
A slab can be well insulated with dry soils underneath it without foam, since the soil does have an effective R value. There is no wind or draft coming up through a slab like there would be in a poorly insulated wall or roof.
You cannot tell the slab is performing poorly except the flowers around the building start out earlier.
Here is where you can really tell: when you hit that marginal site, with wet soils that someone has not set up to drain right, the moisture is going to wick up through the relatively thin foil wrap and it is going to be lawsuit time.
This is exactly what is happening right now in Vinalhaven, Maine at Vinalhaven High School.
The architect got sold a bill of goods on foil wrap (HEY, its shiny, it must be good!?!) and he spec'ed it for the entire school.
It is a marginal site with a lot of ledge. The entire school has a radiant slab with carpeting over it, except for the gym, that has foil faced wrap with a radiant slab over it, then a 6 mil moisture barrier on top of the slab(?),then two layers of plywood and then the hardwood gym floor. In two years, the gym floor starting cupping. Moisture is coming up through the "insulation". The subfloor is rotted and now the lawyers get to have fun.
So here's my two cents worth on this whole issue: Are they using this in Europe? This seems to be our test bed for radiant and heating technology.
Are you prepared to get sued if this happens to you? I think that most installations will never have the problem they have in Vinalhaven, and it is hard to quantify heat loss through a slab. Why no Factory Mutual testing of these products? They all seem to have some other testing to offer as documentation. I am not ready to accept Joe's Insulation Testing Service.
Are you?
If these materials are this good, let's see it used in walls and roofs since 1-2 inches ought to be equal to about R-40 by their calculations, no?
There is no free lunch when it comes to physics and the laws of nature. If it sounds too good to be true, you should think seriously about what you are selling!
Tom |
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NRT.Rob
Registered Users
Posts:338
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| 05/24/2006 10:27 PM |
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Tom, I haven't heard of you before, but I like you already.
-=Northeast Radiant Technology, LLC=-
www.NRTradiant.com |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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jackofalltrades
Registered Users
Posts:0
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| 05/31/2006 8:08 PM |
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I found and bought 100 4x8 sheets of foam insulation 3 inches thick and would like to use it under my slab in my basement. I bought it for 3 dollars a sheet so it was a buy I couldn't pass up. It is white and not as dense as the pink or blue board found at the builders stores. Any problems using it? and should I have my poly barrier over or under the insulation. I have seen it both ways but am planning on using the barrier under the foam. And should I use extra rebar or glass in the concrete for that extra strength that might be required?
I hope I am not creating a problem down the road by using this type of insulation, but at three bucks a sheet, well?? |
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NRT.Rob
Registered Users
Posts:338
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| 06/01/2006 10:55 AM |
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big question is whether its compressive strength is adequate for this application.
I believe vapor barriers, in general, should be installed on the "warm" side of insulation.
-=Northeast Radiant Technology, LLC=-
www.NRTradiant.com |
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-=Northeast Radiant Technology=-
NRTradiant.com |
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tomgocze
Registered Users
Posts:2
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| 06/01/2006 10:05 PM |
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JW,
That was a good deal on the 3" foam. It sounds like expanded polystyrene (EPS).
Most EPS is usually 1 pound per cubic foot density. This has a compressive strength of about 10psi. Styrofoam and polyiso have higher psi ratings (20-30psi). They are usually 2 pound density. Density seems to be closely related to bearing strength.
I would be a little nervous about using it. You can check its density by weighing a sheet and figuring out the weight per cubic foot. If it is not too highly loaded, it can be fine with the good reinforcement.
I would consider putting the vapor barrier on the bottom, this way if any moisture does find its way into the foam, it will dry to the interior of the building. This is a matter of opinion. Some building scientists will say put it on the "warm" side. I suspect that it does not matter that much. |
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jackofalltrades
Registered Users
Posts:0
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| 06/04/2006 7:56 AM |
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Thanks for the info!
I decided that when working with cement not to
spend a dollar to save a dime. So I bought and installed higher
density foam, not wanting to find problems with my slab a few years down the road. The white foam will be put to good use insulating the walls of the walk out basement.
Now for the funpart, laying down tubing today. A new day, a new adventure!
JW |
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