Removing dirt and mold from brick patio

My patio is made of red bricks, which are very nice except they are very dirty and probably have mold on them. How can I clean them?

GINO MARRINUCCI, Walpole

Pressure-washing should clean them up very nicely. You can rent a pressure-washer. If your bricks are in sand, with sand sprinkled in the joints, the pressure-washing might scatter the sand, but after it dries you can sweep it back in where it belongs.

Another method: Mix one part household bleach in three parts water and apply this to the patio; let it sit for 5 minutes without evaporating (add more if it starts to evaporate), then scrub if necessary and, finally, rinse. Wear skin and eye protection when working with bleach.

I have two two-car garages on concrete slabs. One garage is well insulated, but the floor is damp in summer, looking as if someone just hosed it down. The other garage's slab was poured on 6 inches of crushed stone, and is as dry as a bone. What's wrong with the first slab, and how can I prevent that just-hosed look?

Those 6 inches of crushed stone under the slab make all the difference; it provides drainage, so little or no water vapor gets through. That slab also may have a plastic vapor barrier under it, making it even tougher, in fact impossible, for vapor to get through.

The other slab was probably poured on bare earth, providing a perfect path for water vapor to go through it. Water cannot go through concrete, but water vapor can and will. If there is a crack in that slab, water vapor and water will find it soon enough. The solution? You cannot stop it but you can accommodate it by ventilating the garage to release the water vapor that comes up through the slab. You can also run a dehumidifier, but they are expensive to operate, so do so only in the most humid months, July and August.

I am having a terrible time removing the wood strip that separates my two-window sash. I think it is called a bead of some kind, but I just can't get it out without breaking it. I have to remove it so I can take out the sash for repair.

R.B., Lexington

You are half right. It is called a parting bead, because it keeps the sash apart. And you are 100 percent right that it is, or seems, impossible to remove without breaking it, unless you know or learn how to sneak it out. And there are ways. The bead is free floating; that is, not nailed. It fits in a groove loosely, held in place by a notch in the bottom of the upper sash and a notch in the top stop, a small board nailed to the top of the window or held in place by the side stops. Sometimes if you remove one or both side stops, the top stop will fall right down. Anyway, remove that top stop, lower the upper sash (you have already removed the lower sash), and pull out the bead from the top down. If that doesn't work, try twisting the bead with pliers so it slips out of the notch at the bottom of the lower sash. lf all else fails, you can trim the notch to release the bead.

The Handyman has done this with 17 windows, and might have broken two, probably more out of impetuosity than ignorance.

My roof is 17 years old. I asked a roofer to put in soffit vents and a ridge vent, and he said I need a new roof. What should I do?

MANNY ABRAMS, Natick

Get rid of him. Unless the roof is defective and he can prove it, that roof has 8 to 13 years of good service left. It is true that it is easier to install a ridge vent when a new roof is applied, but it is definitely possible to put the ridge vent on the old roof. It's just more work. It requires removal of the ridge shingles and cutting a 1- to 2-inch open strip in the sheathing on each side of the ridge board, then putting on the ridge vent, and ridge shingles on top. This is a little more work, but a competent roofer can install the vent in a day.

I am helping my daughter put in an a/c unit in a vinyl window. I am having trouble getting the ''wings" of the unit to stay in place in order to seal the unit against the outdoor heat. I am concerned about screwing or nailing into the vinyl. Gluing might be OK except I want to take the unit out during the winter. Any great handy ideas?

OSCAR FREITAS, New Bedford

Unless there are any special ways of handling the vinyl windows, I think gluing is your best bet. But instead of putting a bead of glue along the whole end of each wing, put two or three dabs of adhesive caulk on each end; that way you can pry or cut off a dab of glue more easily. I don't know if it is a great idea, but it can work.

I am insulating my turn-of-the-century, three-level Victorian. What is the best stuff to blow in the walls? The third floor is finished but not occupied, but it may be in the future. Should I do just the first two floors or the entire house?

BIG DRAFTY HOUSE

A good blown-in insulation for the cost is cellulose, with fiberglass a close second in insulating value. Even better is a new foam called Icynene, but it is quite a bit more expensive. By all means, do the whole house while you are at it. It would not hurt to blow insulation in the floors (first, second, and third), which would make it easier and less expensive to heat and cool, and will make zoning of the heating system much more efficient if you plan to do that. The first floor is, of course, the basement ceiling, which should be insulated, regardless of where else you insulate.

I have light-green lichen on my roof that seems impossible to remove. I was told that power-washing will remove it. I can't use copper sulfate because of possible contamination of the well water. Should I power-wash?

JAMES KU, Hillsborough, N.J.

Power washing will remove the lichen but also the gravel on the asphalt shingles. Don't do it. Let the lichen alone. It is harmless.

There is one thing you can do to deter further growth: Install zinc strips under the second-to-last course of shingles near the ridge of the roof, with about 3 inches of the strips exposed. Rain will wash off a bit of zinc and flow over the roof and any mold or algae, deterring its growth; lichen is a combination of algae and fungus (mold). It may not kill what is there, nor remove it, but it can prevent future contamination. The strips are sold by Gutters Direct, 800-989-8802, ext. 250.

My Andersen French doors tend to expand and contract, and this summer the sill swelled up and one door stuck at the bottom, tearing the rubber weather-stripping gasket. Is there a way to adjust that door so the gasket will not scrape so hard? Where can I get a new gasket?

BROOKS, Sudbury

Aha! You came to the right place. A friend of mine, a colleague at the Globe, had a similar problem with her Andersen door, and called Andersen. She not only got a new gasket, but instructions on how to install it, and how to adjust the door. So, call Jeff Engle, customer-service supervisor, at 651-264-5150.

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