Insulation ?

RayH

I'm installing radiant heat in a basement slab. What is the prefered insulation to use ? Thank, Ray

Snowmelt

im thinking anything with a .5 r value or better

Zman

You absolutely don't want any product that claims reflective properties like "double bubble".

I would recommend any closed cell product with a weight rating of 25 psi or better. Dow Blue Board or field applied sprays are commonly used.

The energy code should call out the required R-value for your zone. R-10 (2") is a good place to start.

hot_rod

I think some codes now require 2" minimum. About 5 per inch R for the blue and pink foam boards, and they are intended for under slab use.

Or the CreteHeat products with the knobs to hold down he tube, you get a vapor barrier included with those products.

GroundUp

2" XPS is R10 and what I use as a minimum on all installations. As was mentioned. That "double bubble" crap is a joke at best

nibs

Ray, am a newbie so do not know if you are DIY or pro.
If it is DIY you can sometimes find Used Dow Roof mate EPS that a roofer has taken off a flat roof, it is 4" thick stepped and has a good PSI, you can walk on it with boots and not leave heel marks.
You can lay it on a vapor barrier, tape the joins and have R20 for a lot less than the big box hardware stores. You might check with your local inspector to see if he will accept it. He should it is excellent closed cell material.

nibs

Dennis, why would Hydrofoam have a different response to the movement of heat, than say XPS, or other closed cell foam?
Trying to learn as much as possible about insulation thank you.

Gordy

^ it doesn’t. At least not more so than any other similar product as hydrofoam.

As a matter of fact a tube fully encompassed by the concrete is more effective at heat dispersal/ exchange than tube laying on the foam inslation covered in concrete. A fraction of the tube unless it floats off the foam during pouring is against the insulation medium.

RayH

Has anyone ever used Rapid Grid for Viega ?