I am currently working on a project with radiant heating in the slab and we
are planning to place crush rock base, sand or crusher fines, 10 mil
visqueen, then rigid insulation below the slab. We do plan to embed radiant
piping in the slab, however some systems can be placed directly under the
floor cover or in a topping slab/mortar bed.
The general indicated that the insulation was not required, but that's how
he has normally installed it. All my solar home books have the slabs
insulated below as well. You may want to check local energy codes like title
24 in CA. The UMC requires that the piping embedded in the slab be
continuous with fused joints. There are numerous radiant systems on the
market so you might want to check out builderonline at
or Roth who manufactures the systems at
If the project is located in an area subject to freezing, make sure the
system is completely drained after testing. I've heard some horror stories.
Robert Shaffer, PE
Santa Cruz, CA
From: JCohen [mailto:jccpc(--nospam--at)email.msn.com]
Sent: Wednesday, April 04, 2001 7:19 AM
Subject: Radiant heat systems
I am interested to know if there are any codes/standards/guidelines on
designing and installing radiant heat systems in ground slabs. I have been
unable to locate any through Internet searches. Manufacturers/designers also
do not list any.
There is a question regarding the requirement (vs. need) for underslab and
foundation insulation and embedment of the pipes within the concrete.
Many thanks for any response.