Q. Our ranch has typical hollow interior doors. The outside layer (plywood?) at the bottom of one of our closet doors is warped a little, enough that it won’t close. Is there a way to unwarp that small section (about 2 inches by 1 inch), or do we need to replace the door?
GEORGE HARRAR, Wayland
A. The outer layer of plywood makes me think you have a lauan door, which is very stable. Hollow-core lauan doors do delaminate, however — the outer plywood layer peels and splinters off at an edge. Sometimes this can be remedied with glue and clamps, and at other times you can sand or apply wood Bondo.
But if your door is warping, I’m guessing you have a different type. There are a few remedies for a warped door, none of which I have the patience or time to do. I would replace the door because that’s the easiest solution, but if you have more patience than I do, here are tips for flattening a warped door:
1. Remove the door, sand, and seal it with primer or polyurethane on the top and bottom edges.
2. For a slightly bowed door, take a heavy weight and lay it across the area that is warped. Leave the weight on the door for 24 hours or until the warp is gone.
3. For a badly warped door, apply wet towels across the warped area only. Each day, re-wet the towels and add 5 to 10 pounds of weight on the door until the warp is gone.
After the area dries, apply a coat or two of finish to the whole door.
Q. A few of the doors in my house will not stay open. They slowly swing close or partially closed, and I need to use a door stop. I have a newly renovated house on an older foundation with settling, of course. Any suggestions on a fix?
JAN ARDIZZONE, Andover
A. Try this trick:
1. Remove one hinge pin.
2. Place it on a concrete floor.
3. Hit the pin hard in the middle with a hammer.
4. Insert the pin back in the hinge, using the hammer to tap it in place.
The slightly bent hinge should keep the door open.
Q. Can dirt or soot that appears on walls above electric baseboards be removed? If not, and the walls must be repainted, how do I prevent it from appearing again?
We own a 1994 Colonial with a finished walkout basement that has electric baseboard heat along two exterior walls (the rest of the house is gas-fired forced-hot-water baseboard heat). The winter after we moved in, I noticed dark streaks above the baseboards that looked like dirt or soot. When I tried to wipe down the walls, it only smeared the stuff around, making it worse. I am assuming that the walls will have to be repainted. Is there a trick to remove the streaks from the walls? If not, what could be the cause, and how can I prevent it from reappearing after I’ve repainted?
I’ve searched the Internet for a solution (using the term “ghosting’’), and some attribute it to candles, which we do not burn in the basement. Others say there may not be proper ventilation.
A. I have this ghosting phenomenon at my house too, but only on exterior walls. The dirty streaks that can appear above your baseboard are mostly created by dirt, dust, or carbon soot from a number of sources like candles, fireplaces, pets, cooking byproducts, etc. that are spread by the natural convection created by rising and circulating heat. It’s sticking to the wall because the warm, dirty air from the baseboard heater is contacting the colder exterior wall surface.
There is no magic solution. I wash the walls with soapy water and a sponge and make sure to vacuum the baseboard regularly. For stubborn stains, you can also try Mr. Clean Magic Eraser.
Rob Robillard is a general contractor, carpenter, editor of AConcordCarpenter.com, and principal of a carpentry and renovation business. Send your questions to firstname.lastname@example.org or tweet them to @robertrobillard. Subscribe to the Globe’s free real estate newsletter at pages.email.bostonglobe.com/AddressSignUp.