I was thinking of using the Styrofoam-type rigid insulation I've seen recommended for basement walls, supporting it every so often by an appropriately thick piece of wood similar to what is done for the walls—wood, insulation, wood, insulation.

I don't want to build this up so high that there's a big difference between the floor in the bedroom/hallway and the bath (to minimize the potential for tripping), but I'd like to do something to make it a bit warmer in there without going to great expense.

The house was built in 1990, shows no sign of water problems, and is not in an area prone to water issues.

The floor is quite level and doesn't have any stress cracks, etc., in the bedroom/bathroom area.

Any suggestions?

I'm sorry to be so blunt, but you are creating way too much work for yourself.

A built-up wooden floor system on concrete such as you describe will only set you up for water damage and mold growth down the road. Besides, it's not necessary to build up the floor to get warmth under your feet; I have a better solution.

In a bathroom basement, for that matter, any bathroom, I recommend tile, such as unglazed mosaic, pavers, or quarry, as a floor covering. If you insist on carpet, then use throw rugs over the tile. If you just have to have wall-to-wall carpeting, do not glue it down or tack it in place. Then, if the carpet gets wet, it can easily be taken outside to air dry. Wall-to-wall carpeting will require a finished floor, e.g., vinyl, to protect the wood underlayment if your bathroom is built on a wooden floor system. Professionally speaking, I think throw rugs over tile work best.

Since floor tiles are cold in general and will become even colder when placed on a concrete slab, I recommend a floor-warming system by SunTouch that will keep the tiles and your toes toasty warm. I installed this system in our own bathroom.

I like this system because it uses an extremely flat orange mat that only increases the overall finish floor thickness by 1/8- to 1/4-inch, depending on the thickness of the thinset applied. SunTouch's floor mat kit is available both in 120 or 240 volts and includes all the parts necessary to complete the system: wall-mounted thermostat, floor temperature sensor, and double-sided tape to secure the mat.

The system can be installed over a wood floor joist system or onto a concrete slab floor. However, it's helpful if there's insulation under the concrete slab to help direct the heat into the room and not down into the ground (but don't be alarmed if it's not).

SunTouch's video will help guide you through different types of installations and floor finishes. A good tip is to install a second sensor wire in the floor and leave the wires dormant in the electrical box. If the sensor unit should fail, you can disconnect the original wires and hook up the backup wires, which eliminates tearing into a tile floor to replace a failed unit. Unfortunately, I didn't do that on my project.

Also, I didn't position the mat completely under the cabinet toe-kick and I wish now that I had. I can sure tell where the mat ends: right where my toes land. In order to get the mat under the toe-kick, I would have had to install it under the toilet, which is normal when all the plumbing is on one wall but I had some concerns about that at the time of installation. However, the manufacturer does say that the mat can be installed 4 or 6 inches from the toilet's wax ring, which is approximately 20 inches out from the wall.

The mat can be embedded into the tile mortar at the time of tile setting, but I don't recommend it because it's too easy to damage the heating elements. Instead, secure it in place using the double-sided tape and then just cover the mat and heating elements with a thin layer of thinset mortar (not pre-mix). Be sure to use the flat side of the trowel to avoid damage to the elements. Once the thin-set cures, it will protect the heating elements from the notched side of the trowel required to apply tile mortar.

To learn more about the product, go to www.suntouch.com. To purchase a kit correctly sized for your application, call them at 888-432-8932.

Now, imagine...you set the thermostat to come on two hours before your morning shower so you're asleep while the floor warms up. Then you'll step onto toasty warm tiles that are waiting for your bare feet. It'll be like a walk on the beach!

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C.R.S., Inc. · Spokane, Washington · USA