radiant ceilings

Mike Lampkin_2

and customer would like to have radiant installed in the
ceiling. I am looking for ideas to leave the drywall in
place and install the radiant below the drywall. There is
no insulation above the drywall. I am thinking of attaching
r-foil to the drywall,then strap ceiling with something like
1X4 spruce, so that plates could be attached, and then re-
drywall ceiling. Do you require a one inch spacing between
the r-foil and the plates for this to work properly?
Thanks, Mike Lampkin