Layering Insulation under concrete.

[Leaflessshadetree]

I can't believe I couldn't find any existing threads on this.

Getting ready to pour a 1800 sgft "radiant ready" concrete floor.
It appears that I can get 3 sheets of 1" thick insulation quite a bit cheaper than buying 3" thick insulation. with multiple layers I would stagger the joints between layers.
Is there any reason why I shouldn't put 3 layers of 1" thick insulation under my concrete floor to get the 3" thickness I desire?

 

[aptdweller]

I think the main thing is that it is going to be more work, but otherwise you should be fine. Just remember to buy the correct pressure rating, as some foam insulation isn't rated for under-floor use. Don't forget the cost of tuck tape or whatever else you are planning on using to joint the insulation together.

 

[fickster03]

Any more advice? Found some from farm trek n thought bout using theirs

from central Missouri. cattle man live like there's no tomorrow.

 

[Jess]

It will be fine. I used 2 layers of 2" extruded foam under my floor, staggered the joints and put rebar and mesh on top before laying out the pipe. The mesh makes it easier to get the piping to stay where you want it for your design. I have also used foam staples in the smaller rooms and they work ok. Mt floor is only 1200sq ft and we used over 400 tyewraps to secure the pipe before they pumped in the concrete.

 

[LJFULLER]

Compare and make sure the 1" cumulative "R" value and compressive strength are the same as the 3". It might be cheaper for a reason

 

[buddyboy]

how much cheaper? go 4 or 5 layers!!

just make sure the only difference in the 3" and 1" is just the thickness

you don't want the foam that can hold water