If there's one skill that separates a master carpenter from a contender, it is stair-building. A lot of people can frame walls, hang drywall and put down tile, but not that many contractors these days can build stairs from scratch.
Most stair-building has been delegated to specialty shops, or, in the case of new construction, is mass-produced.
The specialty shops and factories both produce great stairs. But shop-built stairs don't always fit in a rehab situation. Floor-to-floor heights in old houses are hardly ever conveniently 8 feet. The only alternative is site-built stairs -- by someone who knows what he or she is doing.
Stairs have to be built so the treads are absolutely level, and the step heights are absolutely consistent. If either is just a little off, the stairs will be difficult, uncomfortable or just plain dangerous to climb.
Tracy Kidder, in his book "House" (Houghton Mifflin, 1985, $17.95), which describes in detail the human and mechanical process of building an elaborate Greek-revival house in New England, has a passage that illuminates the art of stair-building:
"In stair building," he writes, "the steeper the stair, the taller the risers between the treads and the narrower the treads. All the books . . . prescribe that the width or a tread and the height of one riser should add up to 17 or 18 inches. The collective, successively refined wisdom of the tribe of carpenters seems to have produced that formula. It is the one that works best for the largest variety of human feet. A more basic rule for stairs says: Every tread must be as wide as every other, and every riser must be as tall as every other one."
Mr. Kidder quotes Jim Locke, a partner in the house's construction firm, Apple Corps: "It's amazing. You start up the first stair and after that first step your legs know what the rise should be. You can trip on a bump in a flat sidewalk. A quarter of an inch variation will do it."
Mr. Kidder concludes: "Stair making carpenters are like school crossing guards or trainers of seeing-eye dogs. They take on one of society's small trusts."
It takes a heap of stair-building to become a master. But almost anyone can collect enough knowledge to speak the language of stairs and to help in determining if the person to be hired knows what he or she is doing.
This may help:
* First, a little vocabulary. The part of the stair you step on is the tread. The part your toe hits if you swing it forward too far as you are stepping is the riser. The zig-zag frame that the treads and risers are nailed to is the stair carriage. The notched side board that finishes the stair is the stringer. Rise and run is the height of a riser plus the width of a tread. A flat platform at the top or bottom of a set of stairs, or one in the middle that allows a change of direction, is a landing. Wedge-shaped treads that take the stairs around in a half circle, or part of a circle, are called winders.
* If you are building a new house or doing a gut rehab where you can relocate the stairs, consider figuring out where they will go before you decide on room layouts. Remember that stairs serve as natural ventilation; where you put them can have an impact on your heating and cooling layouts -- and on the costs.
* Three common types of stair layouts are the straight run, the long "L," and the narrower "U." Some stairs replace landings with winders, which save space. If you're trying to fit in a stair with winders, check local building codes first; some locales won't allow them.
* If you have to have a door at the top or the bottom of a landing, make sure there's enough clearance to open the door without having to step up or back to get out of the way. But doors at the very top or bottom of stairs are not a good idea from a safety standpoint; it's too easy for someone going the other way to crash the door into an unsuspecting person carrying laundry or groceries. Try to avoid that kind of layout.
* Minimum head heights -- the distance from the treads to overhead obstructions -- on main stairs should not be less than 6 feet 8 inches. (Basement stairs should be not less than 6 feet 4 inches.)
* Open-riser stairs -- often used in basement steps -- need treads about 2 inches wider, to add extra foot support.
* If you are redesigning the space, a main stairway should be not less than 3 feet wide. (A basement stairway can be 2 feet 6 inches wide.) If you're putting new stairs in an old stairwell space, however, wider stairs may not work.
The floor joists around the rectangular stair openings have to be framed with double headers (on the narrow ends) and double trimmers (on the wide sides). Changing the width of a set of stairs can create problems in the floor framing, especially if there's a wall along the side or at one end. This is why it's difficult to change the width or length of a stairway in a rehab -- you have to reframe the floors.
You don't need a master builder for every job. But when it comes to stairs, you need to put your trust in an expert.
If you have questions, tips or experiences to share about working on houses, 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.