Floor heat Insulate or not

[Bill Manke]

When doing floor heat are you insulating under slab first? Mine have always been without insulation but been talking to a builder and they say it should be insulated.

 

[Waxman]

I installed the rigid, tongue and groove, foam inulation under my floorslab.

 

[Parker]

You should definitely use insulation under your radiant heat tubes no question

 

[PaulLovesJamie]

Yes, insulate underneath - it will reduce the cost to run the heat.

 

[Eric H]

The insulation is usually spec'ed in the tubing layout instructions.

Beyond that, someone here (I think it was Galen) advised to poor a 4' footing around the apron. To clarify: around the apron, not the building perimeter. I think the 4' footing would drive up the building costs so I plan on putting rigid insulation vertical around the apron. This should keep the heat for "leaking out" under the driveway.

 

[Ric]

25 years ago we did not put down insulation. Now we do. I'm sure it helps... but heat rises and I doubt if there is much heat loss down into the ground...not 4' down anyway.

 

[PaulLovesJamie]

heat rises and I doubt if there is much heat loss down into the ground

yes it does - conduction down into the ground will cause much more heat loss than convective heat loss (ie heat rising). Think about it this way, which will get you cold faster: sitting on 20 degree concrete or standing in 20 degree air? Thats why those "stadium seats" sell so well.

 

[Ric]

yes it does - conduction down into the ground will cause much more heat loss than convective heat loss (ie heat rising). Think about it this way, which will get you cold faster: sitting on 20 degree concrete or standing in 20 degree air? Thats why those "stadium seats" sell so well.

Good point Paul. Thanks. I guess I'm not too old to learn after all

 

[pitzerwm]

Hey Paul, maybe its because your butt/etc are more sensitive than the whole body)

 

[PaulLovesJamie]

Hah - yeah, probably.

 

[dpessler]

Put the insulation down. We have one with & one without - big difference. Also, make sure you keep the tubing near the surface. We used "dobe" concrete bricks & rebar to hold the mesh up. The concrete guys never pull it up! Doug

 

[mjwalsh]

I just wonder if the concrete with insulation under it would be more likely to collapse (long term wise) under heavy vehicles than if the concrete was poured directly over a small rock, sand, or even hard dirt BASE. It seems that engineers can be pretty fixated on soil testing under any kind of loads which could include heavy vehicles.

I wonder if there has been any settling from anyone caused by using a less than ideal insulation?

 

[Whale of a Wash]

We have floor heat which is only the first 3 feet perimeter around our car wash, so that doors don't stick and to reduce ice. It also heats the washes, it has 2" of blueboard foam under the sand, and in 15 years is still in perfect condition. I think the concrete disperses the weight over a larger area.

 

[Dirtychuck]

Yes, insulation does help.

We used a product from our local heating supply house called insultarp:

http://www.insulationsolutions.com/products/insultarp/information.html