Installing foam insulation is not a do-it-yourself job

DAGIMP, in Hotton’s chat room

A. No, installing foam is very tricky, and too often the foam, which expands greatly, can cause the walls to bulge. You can blow cellulose into walls with less likelihood of distorting them because it is easier to handle. Also with foam, you must make sure it is nonflammable. I think Icynene is the best of the foam, and it is installed by professionals, usually on new construction, or on walls that are open to the studs.

Q. My family room and a bedroom have concrete floors set directly on the earth. Years ago the family room slab dropped considerably. The contractor came and fixed the problem, adding a new layer of concrete. Now the bedroom floor slab has dropped, but only about 2 inches at one end of the room, making the floor slightly sloped. Why does that happen, and can the contractor fix it as he did in he past?

BARBARA, Salem, N.H.

A. The occurrence is rare, though there are plenty of homeowners who would tell you otherwise. Water gets under the slab and erodes away the earth and crushed stone underneath. It can also occur on earth that was not tamped (compacted) or was not tamped enough. Normally a builder can add concrete on top of the dropped concrete. In extreme cases, the old concrete must be taken up and new crushed stone or stone dust must be added before laying a new slab. Also, in some severe cases, hot water baseboard radiators may have to be raised. In your case, with a 2-inch drop, you can leave well enough alone or the builder might be able to put a level layer of concrete on top of the old. Q. My deck is white pine, with a few pine trees nearby. I am plagued by lots of drips of pine tar on the wood. How can I take it off?

MAURICE LEVIN, Amherst

A. If the drips are dry and stiff, you can scrape them off. If the drips are sticky, dissolve them with denatured alcohol. Some call the drips tar, others call them resin. You can’t stop it, and I don’t think you want to cut down those pines. In fact, the tar may be coming from the deck pine. I have several exposed pine or fir beams in my old house, and some of them (all are very old) are still exuding the yellow sticky stuff.

Q. I am redoing my kitchen, and I am plagued by an exposed beam that is 24 feet long and supported in the middle by a wooden post. I would like to remove it. If I do, or can, I would reinforce the beam by putting strong steel sheets on each side of it. Is that possible?

JOHN

A. Don’t even think about it. I don’t know the rules that require posts under exposed beams, but I am sure you cannot take that post down. Check with a structural engineer as to what you can do and how to do it. I doubt that you will ever be able to remove that beam without major renovations.

Q. I have been having a problem with a leaking fireplace. I have checked the concrete cap or crown. There were some hairline cracks, so I put a new skim coat of cement on top. I have two of those wire covers. It seems that when it rains straight down with no wind the fireplace is completely dry. When there is a driving wind with rain, the fireplace gets wet. The water is coming straight down the ceramic inserts. I was told to check the flashing, with no good results. I have also been told that I can coat the entire outside of the fireplace with a sealer to stop water from being absorbed through the brick. Any thoughts or suggestions? I thought of moving the wire mesh caps to cut off any entry points. My wife is getting impatient.

LOUIS T. GIARDINI, by e-mail

A. Since the water is coming down the ceramic inserts (they are called clay flue liners), there probably is no problem with the flashing or the bricks. Extending the steel cage chimney caps might help, but it would require larger caps. But before you do anything, check those clay flue liners as they come up through the concrete chimney cap that you skim coated. Those flue liners should extend at least 2 inches above the concrete chimney cap. This is to prevent horizontal wind-blown rain from going right down the flue. If your flue liners are flush with the concrete chimney cap, that is the problem, and you can extend those clay flue liners by at least 2 inches. You can cut a regular clay liner to 2 or 3 inches and install it with thin-set mortar. If your flue liners are already sticking up through the cap, then a new, different kind of steel chimney cap is needed, restricting that horizontal rain.

Globe Handyman on Call Peter Hotton is also in g on Thursdays. He is available 1-6 p.m. Tuesdays to answer questions on house repair. Call 617-929-2930. Hotton also chats online about house matters 2-3 p.m. Thursdays. To participate, go to www.boston.com. Hotton’s e-mail is photton@globe.com