Zolton Cohen Cold floors Warm them up with insulation, heating systems

Zolton Cohen: Cold floors? Warm them up with insulation, heating systems

Zolton Cohen Q: I have two rooms with marble tile floors. One is over an unheated crawlspace; the other is over an unheated basement. The floors were installed before there was the option of putting warming pads under the tiles. Is there any way to warm the floors with a product that goes between the floor joists, or any other way?

A.L. Climax.

A: There are several options you could explore to help warm up your marble floors. One would provide localized heat via electric pads stapled to the sides of the floor joists under the subfloor somewhat similar in nature, though not identical, to the electric mats that are placed under tile floors as they are being constructed.

Another choice would deliver warmth from hot water running through plastic tubing placed under the subfloor. A third would entail incorporating the crawlspace and basement into the houses living area, providing them with heat, thus warming the floors from the underside.

Companies like Sun Touch (www.suntouch.com) make electric mats that can be stapled to the floor joists, two inches under the subfloor. Insulation is added under the mats and a thermostatic control device is wired into the grid.

Electrical mats, however, are not an inexpensive system, either to install or operate. The mats alone run between about $13 to $15 per square foot. Wiring, thermostat, installation and insulation add to the cost. Drawing about 10 watts per square foot, a 100 square foot area would draw 1,000 watts one kilowatt of electricity per hour. At, say, 12 cents per kilowatt, thats $2.88 per day if the mats were left running 24/7, less if operated intermittently.

A hydronic radiant tubing system might be worth checking out, in particular if you are able to use your existing water heater as the heat source. Youll have to check with your local building code official to get clearance on that issue. Hydronic systems utilize a small pump to circulate water through plastic piping stapled under the subfloor. Insulation installed under the pipes helps direct the heat upward. Because youre only seeking to warm the floors rather than heat entire rooms, a water heater would be more than sufficient to supply the heat required for both the domestic water supply and the flooring.

Though you could install the PEX plastic tubing and insulation yourself, youd need a local professional to hook the system up to the water heater and to the pump and control unit, and any zone valves. Online sellers of these systems, like www.radiantec.com, offer good illustrations and engineering help to design an installation.

It is possible that the least expensive way to go about this project would be to warm up the basement and crawlspace so heat would migrate through the subfloor and into the marble. But the only way that would make sense would be to first insulate both areas so the heat isnt lost to the soil and air surrounding the foundation.

The crawlspace, in particular, would first need to be evaluated for moisture and air infiltration problems, and any deficiencies remedied. Then rigid foam panels could be applied to the inside of the foundation walls of both areas, as well as to the floors. Forced-air heat runs could then be diverted into those locations, and the only place for the heat to go would be upward, into the floor system.

Although this method wouldnt result in floors as warm as could be achieved by the other ideas mentioned above, it might provide enough of a boost to make them reasonably livable and probably at less initial installation and operating cost.

Zolton Cohen is a Kalamazoo-based newspaper columnist and former American Society of Home Inspectors-certified home inspector. Write to Zolton B. Cohen, Around the House, P.O. Box 2007, Kalamazoo, MI 49003.

Leave a Reply