Radiant heat insulation

[383 240z]

With my new build I am wanting to add in-floor radiant heat.

My first issue is how to best insulate the slab from the ground. What are you guys in the Northeast using? The general consensus is sheet foam over washed gravel works best, but some quick math tells me that I will need 63 sheets for R-10 and 126 sheets for R-20, at $32 a sheet that's a little over $4000.

That is based on $32 a sheet for the 2" thick pink 4x8 sheets from Home Depot.

What other options are out there? Is the pink insulation the right material for this? Is there a better option, or a better place to purchase it?

 

[Randy in Maine]

I went to the local concrete supply place and they sold me my 2" of rigid foam 4x8 for a little less than $32 a sheet (about $1 per square foot). R-10 is fine and it is a good thermal break from the heated floor to the unheated ground. They also delivered my 6'x 6" mesh wire (4'x10' sheets) that I attached my pex tubing to.

 

[thoyer]

I had my builder get the 2" sheets at his cost - approx 32 sheets were used. 2" is what the radiant floor heat manufacturer called for in my installation. We used 1/2" rebar on a 15" grid spaced 2" off of the insulation which put the tubing centered in the 5" slab. I tied the tubing to the rebar. I did the tubing install to save on labor.

 

[Chris705]

I was able to find used insulation on Craigslist...... saved me a ton !

 

[Mark_17]

Talk to contractor services (pro desk) at the home depot, They might be able to give you a better price

 

[DJF3]

Find a building supply wholesaler. They will be much less than Home Depot. Not sure about the states, but in Canada wholesalers are not allowed to actively advertise. But if the yellow pages still exist, they should be listed under Insulation.

 

[dbldmnd]

For my build, 40x64, I needed R15 under the slab to meet code. I bought my insulation from home depot. I was able to custom order 64 sheets (only available in a pallet of 32 sheets) of 3 inch R15 and get bulk pricing and delivery. Then for the remaining area I doubled up 1.5 inch R7.5 using 32 sheets from HD. I priced out insulation from HD supply Whitecap, but it was cheaper from Home Depot with bulk pricing.

I used 6"x6" wire mesh 8 foot x 20 foot sheets with 1.5 inch stands and 10 mil vapor barrier. I bought all of that from HS Supply Whitecap as it was cheaper than anything from Home Depot.

For all the radiant tubing and manifold, I bought everything from supply house.