Question: Some of the floors slope in my condo on the third floor of a triple-decker. The slopes go from the sides of the house to the middle. I don't mind the slopes, but recently they have gotten a bit steeper, and there are some squeaks when I walk on the floor. Can those floors be straightened out and the squeaks stopped? If so, how? — Kara Scheyette, Cambridge
Answer: You might be able to straighten out the floors, but you would be better off keeping the slope from getting steeper. The squeaks can be stopped by screwing the top floor tighter to the subfloor and both floors to the joists.
Here is what happened. The house is too wide to set up joists to span 20 to 30 feet, so a large beam is installed in the basement, from front to back, right in the middle, with ends sitting on the foundation and the intermediate parts supported by posts. Then, joists are set from foundation to center beam, a short enough span for one joist to cover. Joists are also set from the opposite foundation to the center beam.
The house is then built on top of this floor, and in the case of a three-decker, there is a lot of weight on that floor and on the center beam. As each floor is built, a wall is installed over the beam, or close to it, on each floor. These are called carrying walls or load-bearing walls, because they support what's above them. Now, back in the basement, there are wood or steel posts supporting the beam every 8 feet or so. Woe betide anyone who takes down those supporting walls and/or the posts under the beam.
Sometimes a wood post will rot out, or the steel post, which sets on the concrete floor, will be driven through the floor into the ground underneath by sheer weight. There should be footings under these posts to keep that from happening, but there may not be in an old house.
If a post fails, the beam will sag. This sag is transferred to the walls above the beam, so that all floors are affected. Have an architect, structural engineer, or a certified building inspector look at the beams. It is possible to install new posts on proper footings to keep the slopes from increasing. Trying to straighten them out by jacking up the beam is difficult and iffy. This work is structural and should be done by, or with, a professional.
It appears that the beam has sagged a bit more. If that is so, then it is getting more and more urgent to find someone to fix it.
Question: Is it OK to blow cellulose in the walls without a vapor barrier in an old house? — Emily Sherwood, Lynn
Answer: Yes, it is OK; insulation without a vapor barrier is less effective than insulation with a barrier, but there are ways to provide a vapor barrier. You may already have one. In fact, if you have wet cellulose blown in (some companies do it), the well-packed insulation is a vapor barrier when it dries. Also, the interior face of your walls may be a vapor barrier; vinyl-coated wallpaper or wall-Tex is a vapor barrier; so are most oil paints and many latex paints.
Question: I just converted the heating system from electricity to oil. I noticed that a lot of the cellulose insulation in the attic floor has been disturbed, apparently by air currents, and some of the loose cellulose has been pulled down through the door of the pull-down steps. I spent several days moving the insulation back into position. My two questions are: Can cellulose be disposed of safely, in case I want to take some away? And how can I keep the insulation from being blown around and sucked down through the stairway door? — J.S., Northborough
Answer: First of all, cellulose is not a hazardous material and can be disposed of at curbside collection. Actually, there is no need to dispose of any; if you seem to have too much, you can re-rake it into a thicker pile, but be sure to keep it out of the roof overhang.
To keep the cellulose from blowing around, put polywrap insulation on top of it, at right angles to the joists. Polywrap is 8-inch fiberglass wrapped in perforated polyethylene, which makes it easy to place over cellulose and other insulation, and keeps the itchy fiberglass away from tender skin.
To stop infiltration through the stairway door, I suggest putting down an insulated cover that is gasketed. This could be 1-inch styrofoam covered on both sides with plywood or hardboard or just a piece of plywood covering the opening.
Write Peter Hotton at the Boston Globe, Boston, MA 02107; E-mail: hotton@globe.com