People who are remodeling kitchens and bathrooms often find themselves up against a wall.
Despite the best attempts to design around it, the wall is still in the way. This isn't cause for despair. It's possible to get that wall out of the way.
How much trouble it will be, and how expensive, depends on what role the wall plays in the structure of the house.
There are two kinds of walls: interior partition walls that simply divide space and don't support any of the weight of the structure; and load-bearing walls, which play an important part in holding up the building.
Partition walls are generally expendable. They may support a ceiling, and if it's plaster and historic, you have to be careful about removing the support. They may also have wiring or plumbing or heating ducts in them that will have to be rerouted. But as long as the wall is simply a room divider, it can be taken out.
Load-bearing walls are a different story. They can still be altered, but the load, or weight, they support has to be transferred to some other weight-bearing element -- the foundation or the ground. Generally this alteration is accomplished by installing a beam at the ceiling level that is supported on both sides by columns. The beam and columns can be relatively unobtrusive -- in fact, the "columns" may simply be extensions of the side walls.
The problem is that it can be difficult to identify which walls are load-bearing, especially if the house is an old one that's already had a lot of changes.
While homeowners may be able to determine what kind of wall is in question, it takes a professional -- a structural engineer -- to determine what needs to be done to change a load-bearing wall. Calculating the load and determining how to transfer it are not areas where you can afford to make mistakes. In fact, in most places, building inspectors will require that plans to alter a structural element be approved by a structural engineer.
Here are some of the considerations that come into play in evaluating walls:
*All exterior walls are load-bearing to some degree. Sometimes exterior walls become interior walls when the house gets an addition. The wall at the low end of every roof is load-bearing. Generally, even with an addition, the roof line will change in some way. For instance, a back addition may have a shed roof; the wall the roofs both touch will still be a load-bearing wall, even though it's inside the house. The back wall of the addition, at the end of the shed roof, will also be a load-bearing wall.
Some exterior walls support only their own weight, or their own weight plus the weight of the roof, because floor supports run parallel to them. Removing such walls still requires structural changes to transfer the load, but the new supports won't have to be as massive as those for a wall that carries part of a floor or ceiling in addition to its own weight.
*Stairway openings in the floor-framing system are supposed to be self-supporting, so that nearby walls have no load-bearing function. But sometimes in old houses the original builders did not follow the rules, and sometimes the house has settled in a way that weakened the stairwell framing. In those cases, adjacent walls take on a load-bearing role.
*Walls that have other walls above them are often, but not always, load-bearing. Many old houses have a load-bearing structure up the center. In such cases, the basement will have a large, more-or-less-central beam supported by masonry columns. Usually the first-floor joists overlap the beam and are supported by it, and any wall above the beam is load-bearing. Even if the joists run parallel -- on the first floor or on any other floor -- the walls above may still be load-bearing.
Sometimes the original carpenters didn't bother to line up the walls exactly over the lowest beam, so walls on upper floors may be offset by a foot or two. However, any wall over the general vicinity of, and parallel to, the basement beam is probably load-bearing.
*In general, walls that run perpendicular to the floor joists will be bearing walls. If you can't see the joists because they're above a ceiling, the floorboards can sometimes, but not always, tell you which way the joists run. Floors that are one board thick are laid perpendicular to the joists. However, if the floor has a subfloor, or if you can't tell how many layers there are or which way the bottom one runs, you'll have to find another method of identifying the load-bearing walls.
Just looking at the first-floor joists from the basement of a multistory house is not enough. We once ran into a design problem in a brick row house because the joists ran side to side on the first floor, but ran back to front on the second and third floors.
If this sounds complicated, it is -- and that's why it generally takes a professional to evaluate a wall and come up with a solution for replacing it.
Next: Loads, columns and beams.
Mr. Johnson is construction manager for Neighborhood Housing Services of Baltimore. Ms. Menzie is Home Editor of The Sun.
If you have questions, comments, tips or experiences to share about working on houses, write to us c/o HOME WORK, The Sun, 501 N. Calvert St., Baltimore, Md. 21278. Questions of general interest will be answered in the column; comments, tips and experiences will be reported in occasional columns.