As hole grows, homeowner's heart sinks

Sinkholes can be caused by improper backfilling of a foundation, usually when the fill contains wood that later decays. (ISTOCKPHOTO.COM)

Q. Help! What started as a curious little sinkhole near the side of my 150-year-old house has grown large enough to swallow up stray dogs and small vehicles! The ground abutting the foundation around a three-sided bow window was lined with an apron of asphalt, about 8-10 inches from the foundation outwards. Slowly, since the spring, a hole appeared and has grown with each rain storm over the summer. Now the asphalt around half the foundation has caved into a hole about a foot deep and up to 3 feet wide. It looks like it might be even deeper in some parts and seems to extend under my porch. I'm worried this will damage my foundation and I can't get my landscaper to come look at it. What causes sinkholes like this, and what can I do?

SINKING, SINKING

A. Sinkholes occur when water erodes earth away, sometimes well below grade or near the surface. Improper backfilling of a foundation, usually caused by wood, tree trunks and other wood products in the fill, which decays and disappears, allowing the earth above to collapse, causing the sinkhole. I don't think that is the case with your ancient foundation. Or, the earth under the new asphalt apron was not filled with the right material (sand is best) or it was not compacted enough. That is most likely. I don't think your foundation will be affected. The only thing you have to do is fill it with sand, and sod over it. If it appears again, keep filling it. It is rarely that you get a deep hole or chasm or abyss that just cannot be filled.

Q. Two of my adjoining rooms have hardwood floors, one honey colored and the other darker, and they make quite a contrast where they meet in a doorway opening. Is there any way to make the light one darker or the dark one lighter so they will match?

CATHERINE NOLAN, Tewksbury

A. There is no way without refinishing one or the other or both. But you can make the contrast less jarring by installing an oak threshold in the door opening. The threshold is a bit higher than the floor, which will help relieve the jarring, and I guarantee no one will trip. I have several in my old house, mainly to relieve different floor heights. One of those differences was 2 inches, and the only one who tripped was my mother-in-law. And she didn't even get mad.

Q. In my 110-year-old house, the 5-inch cast iron sewer pipe is leaking at the joint, not a lot, but there is some seepage. Can I fix it myself?

LOUISE

A. If the joint has been stuffed with oakum, you can buy some at a plumbing shop and put new oakum in. Do it soon because the leak may be releasing sewer gases into the basement, something you definitely do not want. It would be better to have a plumber do it. If the joint is sealed with lead, you do need a plumber and will have to wait a few days. So seal the leak with Gorilla Tape or an asphalt tape that will give a pretty good temporary seal.

That oily 'splat'

When Nancy by e-mail asked about a "splat" of a greasy looking mess she found on her basement floor, and with a brown-black oily substance soaking the insulation in the ceiling above, the Handyman said it might be an oil leak from the oil line to her heater, if indeed she uses oil for fuel.

Here are some of the replies the Handyman received by e-mail:

From Ernie: My kitchen range includes a griddle that we use for pancakes, eggs, bacon, etc. It includes a container to catch the grease runoff. If the container is not emptied it will overflow and eventually deposit on the basement floor. This may be the problem noted in the Globe.

From James Cote of Haverhill: Nancy mentioned the kitchen stove is just above that spot, or nearby. I would have her check her roasting pans for pin holes. A leaking roaster pan could cause that kind of mess. And if someone had carved a bird or roast in the pan, there could very well be pin holes. It has happened to me.

From Jim Slack of Lexington: I think that the oil "splat" is more likely to be grease from the oven than heating oil. Over 20 years, a lot can accumulate. If the copper "pipe" is actually the gas line to the oven (illegal, but not impossible), grease and steam from the oven could be condensing on the pipe and running down through the floor. Regardless, the grease-soaked insulation should be removed from the basement ceiling at once. While it might not necessarily cause a fire, it is does pose a very serious hazard should a fire get started. She could remove it herself or find any home handyman or carpenter. At that point it will probably be obvious what the problem is.

From Sam Havdala: I had a nest of mice in the insulation, and when I pulled the insulation, the droppings were there. The insulation was stained with a black 'oily' substance and it dripped on the floor and desk. There were no pipes or wires around.

Thank you all. In some cases, how that oily stuff could go through two layers of wood floors is a mystery, although it certainly can go through the cracks.

Q. I am renovating my house. I want to install crown molding made of medium density fiberboard. I would like to glue it. What kind of glue would be best? Finally, I know I can't miter the crown molding, but how is it best fitted into corners?

JOE COHEN, Grafton, N.Y.

A. Liquid Nails is a good adhesive, so is an adhesive caulk, but both have to be held in place for a few minutes until the glue cures. Molding that does not work well by mitering into corners can be coped. Instructions on coping can be found in any woodworking book or the Brosco catalog. Briefly, it is done by cutting the end of a molding at a 45-degree angle. Then, with a coping saw (very thin blade good for cutting small corners) cut squarely, following the contours of the inside mitered cut.

Globe Handyman on Call Peter Hotton is also in the g section 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.