WOOD-BURNING stoves provide two kinds of heat: radiated and conducted. Both contribute to the warmth and well-being you get from a fire, but both carry the potential hazard of overheating, even setting ablaze, anything that gets too close for too long.
Radiated heat comes through the air -- it's what makes your face glow when you sit near the stove. Conducted heat is more direct -- the warmth the stove transfers to the surface it is sitting on, for instance.
Radiated heat can become conducted heat if it warms a nearby surface -- say, an ordinary wall -- and conveys heat to whatever is behind the surface -- in the case of the wall, to the studs behind the drywall.
According to the "Visual Handbook of Building and Remodeling," by Charlie Wing (Rodale, 1990, $39.95), most of the heat from a single-wall wood stove comes in the form of infrared radiation. The heat can penetrate combustible materials, alter their composition and make them ignite at lower temperatures. So too much heat could get the studs smoldering before you're even aware there's a problem.
Concrete floor not enough
This is why placement of a wood stove is so important, and why simply setting it on or next to a noncombustible surface, such as concrete or brick, may not be enough: It can still conduct heat to the surface beneath, and that surface may burn.
Conventional wisdom says that all combustible materials -- woodwork, unprotected walls, furniture, firewood, that stack of old newspapers you use to start the fire -- should be 36 inches from the stove. An unprotected stove pipe should be at least 18 inches from an unprotected wall or ceiling.
And if the legs of the stove provide a clearance of less than 6 inches, the recommendation is to install 2 to 4 inches of hollow masonry with a sheet of 28-gauge sheet metal under it.
Floor protection should extend a minimum of 12 inches from the sides of the stove and a minimum of 18 inches from the front. If you have a side-loading stove, the floor protection should extend 18 inches on that side.
Those clearances should be enough to protect you from sparks and embers. You must check the installation guidelines that come with the stove, however, because the manufacturer may recommend broader protection.
The manufacturer's specs are vital because, according to John Altmeyer, supervisor of code inspections for Baltimore County, that is what building inspectors will look at when deciding whether your stove meets code.
There is nothing to prevent you, in the interest of common sense and added safety, from exceeding the manufacturer's recommendations. We think it makes sense to protect nearby walls. The standard recommendation on wall protection is a sheet of 28-gauge metal installed 1 inch from the wall with noncombustible spacers.
You can also use brick on the wall, as long as it is spaced out 1 inch, with gaps at the top, bottom and sides to ensure good air circulation.
At a minimum, the wall protection should be at least as wide as the floor protection. (Note: Old stoves or old installations may have asbestos-containing materials as insulation. If you are going to remove them, you'll need an asbestos-removal expert to tear them out and dispose of them.)
If you don't want to put brick on the floor, you might try using a stove board.
Stove boards available
Charlie Lewis, of Courtland Hardware in Bel Air, said he can order stove boards from two manufacturers. Chesapeake Hearth, a local manufacturer, makes a concrete board that is surfaced with tile, marble or slate and trimmed in oak.
Another manufacturer, Yoder, in Washington state, makes a similar concrete board with a tiled surface and metal trim. Boards can be made to order to fit a corner installation and are testing-lab approved. Prices start at about $220.
Randy's experience of sitting in front of a stove at his family's cabin and watching sparks fly out far enough to singe the carpet leads him to recommend not installing wall-to-wall carpet right up to the stove's floor protection. Wood or tile floors are better in a room with a stove.
Remember added weight
However you install the stove, remember that you will be adding a lot of weight on the floor. You may need to reinforce the joists underneath. A structural engineer or knowledgeable contractor
can advise you on that.
Once the stove is installed, you can check the heat on nearby surfaces: Place your hand on them. If you can keep your hand there while the stove is operating at peak output, then the surface doesn't need more protection.
All of this advice -- three columns' worth -- may make it seem like wood stoves are more trouble than they're worth. But most people who have them love them because they're "off the grid." They work whether the electricity is on or off. In an all-electric house, that can be a big advantage during a power failure in January.
Randy Johnson is a Baltimore home-improvement contractor. Karol Menzie is a feature writer for The Sun.
If you have questions, tips or experiences to share about working on houses, e-mail us at homeworlark.net, or write to us c/o HOME WORK, The Sun, 501 N. Calvert St., Baltimore 21278. Questions of general interest will be answered in the column; comments, tips and experiences will be reported in occasional columns.
Pub Date: 1/12/97