I'm quoting on a set of bookshelves that will have to be built over some baseboard heaters (about 9" high, 3" deep). How should I construct the base of the unit so that it still conveys the heat but doesn't show the heater?
From contributor L:
Is this forced air or hydronic heat? If it's water, be very careful because at some point there may be plumbing problems that can only be resolved by removing your casework. Beyond that, if the radiation unit doesn't "show", how is it going to transfer the heat into the room? At the very least there needs to be a plenum and presumably a vent cover.
In the past I've made ladder-type bases into heat plenums (for forced air heat ducted through the floor) and cut vents into the baseboard of the casework. As a precaution, I screwed a layer of drywall underneath the bottom of the cabinet (at the "top" of the plenum cavity) to insulate the books and cabinetry from heat transfer. This may be unnecessary, but it's easy enough to do while installing the unit and is cheap insurance.
Underneath the unit (at the joints), I used heavy duty furniture levelers to take the some of the weight off the french cleat. I built a removable toe kick assembly that was basically a small face frame with brass wire mesh in the center to let the heat out. I got the wire mesh from Rockler. I placed a couple of rails on this frame to hide those furniture levelers. I put the wall unit high enough above that radiator so that anyone who ever had to work on it could have access. The home owner wanted to cover the radiator up - real bad idea!