Renovating in Modules
By John Thomas
No ones job is simple. If you think it is you probably dont understand it.
Building, however, is reducible to a few basic concepts. Whether youre building new
or renovating, virtually all buildings are made up of repetitive modules of rectangles and
triangles with the occasional curve thrown in. We combine these modules in patterns that
should be level and plumb and square.
Everything is related. If the floors are out of level, for example, the walls sitting on them probably wont be plumb. Then the doors and windows in the walls might not sit level and square and probably wont close properly. And so on
Building is not a pure science, however. Although the modules are abstract, the reality is that we work to acceptable tolerances. In rough framing, for instance, 1/8 is generally close enough. In finish carpentry, 1/32 may not be close enough, depending.
Building new or renovating, the same principles apply. One reason renovating is more difficult, however, is that in renovating youre trying to adjust for the mistakes of others, or the effects of time, which cause buildings to settle, rot, and otherwise go out of whack.
Lets say youre building a wall in new construction. If its new, this is usually a simple rectangle. Top and bottom (plates) are the same length. The studs are all equal, and when its nailed together the diagonals of the wall are equal so you know its square. If it is square, it can be plumbed in both directions. If its not square, it will never be plumb in one direction. Walls meet walls. If the first is out, so will the second be.
Okay, now youre renovating. And now youre trying to attach your new wall to an existing wall thats out of plumb by 2 top to bottom. What to do?
If you build your new wall square and nail it to the out-of-plumb wall, your wall will be forced out of plumb by 2. To make matters worse, lets say the floor youre building on is an old kitchen floor, 2 out of level with a 1 dip in the middle. (Flat and level are different; floors can be flat but not level.)
To correct the problems, you could cut top and bottom plates different lengths (2 to compensate for out-of-plumb.) And you could cut each stud a different length to accommodate for the dip in the floor. The simplest way, however, the fastest way, the best way, usually, is to go ahead and build your wall square but allow for the out-of-plumb-and-level in the existing building by measuring to the shortest dimensions. That is, make the wall square but 2 shorter in length to compensate for the out-of-plumb. And cut all studs 2 shorter to account for the out-of-level, and ignore the dip for now. Then erect the wall plumb and level and shim the gap where it meets the old wall, and shim the gaps in the floor. You may have to prenail the shims or use long nails to nail through.
This scenario recreates itself endlessly in renovating.
When measuring, never assume anything is actually plumb and level and square. It almost never is. If you assume its out of whack from the start, youre already ahead. Then, whether youre building walls, cabinets, roofs, or forms, stick with the modules. Leave room to compensate for irregularities at the edges by measuring accurately to the shortest points, and filling in the gaps. Youll save a lot of time and avoid the frustration of trying to custom cut each piece of the puzzle.