More radiant heat questions.

[Kapt]

I've decided to go with radiant heat, but I have a few more questions before I order the parts.

My local building supply has both the Owens Corning Formular 250 insulation and the Dow Scoreboard, both rated at 25psi. Is this the stuff most have been using under their slab for insulation? A 4x8 sheet cost around $32 for either product.

For the wire mesh to reinforce the slab and attach the PEX tubing, my building supply has 6"x6" grid mesh in flat 5'x10' sheets in 10 gauge all the way down to 4 gauge. Is 4 overkill or recommended? Also, when they pour the concrete is it sufficient to just lift the mesh up into the concrete or should it be elevated in some fashion? My slab will be 4" thick on grade (non-structural).

Anything else to think about before I get the ball rolling on my slab?

TIA Tom.

 

[PAToyota]

I never spec less than 6ga mesh and put it on chairs - less than that and the concrete deforms it. I've seen too many times where a slab is demolished and all the mesh is at the bottom with "tents" where they they tried to pull it up into the slab... The mesh is cheap insurance and you might as well do it right to get the benefit of it.

And either the Foamular or Scoreboard is just what you want - DOW Styrofoam SM is another product that can be used for such an application.

 

[HoosierBuddy]

Great Choice on the Radiant. It rocks.

Dow reccomends their SM product for under slab. It's 30 psi. I got mine from the concrete company. The box stores don't carry it. It was a couple of bucks more per sheet.

Phil

 

[Nosman]

I've decided to go with radiant heat, but I have a few more questions before I order the parts.

My local building supply has both the Owens Corning Formular 250 insulation and the Dow Scoreboard, both rated at 25psi. Is this the stuff most have been using under their slab for insulation? A 4x8 sheet cost around $32 for either product.

For the wire mesh to reinforce the slab and attach the PEX tubing, my building supply has 6"x6" grid mesh in flat 5'x10' sheets in 10 gauge all the way down to 4 gauge. Is 4 overkill or recommended? Also, when they pour the concrete is it sufficient to just lift the mesh up into the concrete or should it be elevated in some fashion? My slab will be 4" thick on grade (non-structural).

Anything else to think about before I get the ball rolling on my slab?

TIA Tom.

It's also highly recommended to insulate around the perimeter, where most of the heat loss to the earth will occur. You might want to be careful lifting the tubing up into the concrete, 4" thickness doesn't allow much room for error if you're going to saw cut the slab. Good luck, you'll love it once it's done.

 

[Scott Pearson]

Here are some pictures of the radiant heat I put in my 40X50 garage.

Scott

 

[boiler7904]

I never spec less than 6ga mesh and put it on chairs - less than that and the concrete deforms it. I've seen too many times where a slab is demolished and all the mesh is at the bottom with "tents" where they they tried to pull it up into the slab... The mesh is cheap insurance and you might as well do it right to get the benefit of it.

I second the chairs. Pulling the mesh up once or twice while the guys are still walking through the fresh concrete is pointless. All the mesh ends up directly on top of the vapor barrier in interior slabs or on the stone in exterior slabs with little or no contact with the concrete. Waste of everyone's time and money.

On a side note, how do you feel about fibermesh in concrete?

 

[toms73novass]

Do you guys have a picture of the chairs that you speak of?

 

[Scott Pearson]

I used Fibermesh in everything. All my footings and the 8" floor in the garage. I also used commercial expansion joints. You have to set them in before you pour the floor. It was a little work but well worth it. No cutting later and not a crack anywhere in the floor. Its over 4 years old now and looks like the day I did it. We poured 52 yards and power trowled it for 6 hours.

 

[PAToyota]

I have seen a number of floors that were literally furry with fibermesh... Personally, I hate the stuff...

Reinforcing chair: http://www.mitre10.co.nz/shop/building_supplies/concrete_and_metal_products/mesh_bar_chair_7590mm_430125.cfm

Also, they just sent me a copy of this guide:
http://www.radiantpanelassociation.org/i4a/pages/index.cfm?pageid=246

Might seem a bit pricey for a special issue magazine, but it does have a fair amount of information and resources - would be worth spending $20~25 before spending thousands on a system.

 

[krooser]

I have seen a number of floors that were literally furry with fibermesh... Personally, I hate the stuff...

Reinforcing chair: http://www.mitre10.co.nz/shop/building_supplies/concrete_and_metal_products/mesh_bar_chair_7590mm_430125.cfm

Also, they just sent me a copy of this guide:
http://www.radiantpanelassociation.org/i4a/pages/index.cfm?pageid=246

Might seem a bit pricey for a special issue magazine, but it does have a fair amount of information and resources - would be worth spending $20~25 before spending thousands on a system.

Mine was 'furry' too...I used a orbital sander to knock it off before i expoxied my floor...took about 15 minutes to get rid of it (1500 sq. ft.)

 

[toms73novass]

I
Reinforcing chair: http://www.mitre10.co.nz/shop/building_supplies/concrete_and_metal_products/mesh_bar_chair_7590mm_430125.cfm

thanks!! PAToyota

 

[70pcuda]

Here are some pictures of the radiant heat I put in my 40X50 garage.

Scott

Scott, I'd love to here more details of your install. What heat source did you use? Do you have a tubing layout I can look at? I am in the planning stages of a 40'x50' building any info would be very helpful.

Also, has anyone used this under their floor: http://www.thebarrierinsulation.com/26201.html

Just wondering how it compares to the 2" foam board stuff.

Thanks.

 

[Scott Pearson]

I will be using an oil fired boiler. I have one big enough to heat boat bottom and top floors. Layout was really simple. 8 zones at 242feet each. I did not use a foam barrier at all. I just dont trust them and really dont know what will happen down the road. I just used a plastic barrier between the stone and the tubing. I have a bunch more pictures if you need them.

 

[70pcuda]

So has anyone used this stuff? Is it as good as they claim?

http://www.thebarrierinsulation.com/26201.html

Thanks

 

[wmonroe]

I am looking at that stuff also, but haven't found anyone yet that has used it.
Hopefully someone that has some experience using it will chime in.
Will

 

[wmonroe]

Scott-I would be interested in seeing the pictures of your install if you don't mind. My email is [email protected]
Thanks
Will

 

[bg71361]

I used the Insulation Barrier in my 30x70 garage. Installation went well, seems like a very good product. I only have one season of heating on my radiant floor system.
Bill

 

[wmonroe]

Bill- What are you using for the heat source? Boiler, Hot water tank, gas or electric?
Thanks
Will

 

[bg71361]

Will,

I used the Takagi T-K Jr. (see link below) basicall a tankless hot water heater, it is a closed system running on propane. I do believe if i were to do it again I would choose an oil fired burner. Propane is not cheap in my area. Let me know if you have other questions, I also have tons of pictures.
Bill

http://www.takagi.com/web2003/c03.htm