Roof cleaning is a job best left to the professionals
Q. One side of my asphalt-shingled roof, which is shaded by a large maple tree, has small growths on it that look like the lichens that grow on trees. There are also black stains on other parts of the roof. How can I clean this stuff off, and what is it?
A. The growths that look like lichens probably are lichens, which can grow on asphalt shingles as well as on trees. The black stains are a fungus. Shingle stains like these are very common, especially in areas of high humidity and on roofs shaded by trees.
Unfortunately, cleaning a roof isn’t easy, and it is usually not a good do-it-yourself project, mainly because roof work is dangerous, especially on wet, slippery surfaces. The only way for a do-it-yourselfer to work on a roof with reasonable safety is to wear an approved safety harness, which can cost $50 or more. The harness must be attached to an appropriate restraining system (not a length of clothesline looped around a tree).
Safety equipment for roof cleaning should also include safety glasses, gloves, long sleeves and long trousers. In addition, ladders must be set up and used according to safety rules.
Many mixtures for roof cleaning are available at home centers and on the Internet, but care should be used in selecting one. Some cleaners contain either chlorine or oxygen bleach, and some experts say bleach should be left on asphalt shingles for no more than five minutes or it will damage the shingles. Other cleaners contain sodium hydroxide, which is the chemical name for lye, or caustic soda, a powerful chemical that can be hazardous if not used properly. Many roof cleaners can also damage plants unless the plants are thoroughly soaked with water before and after use.
For all these reasons, it pays to hire professionals to clean the roof — but it is sometimes difficult to find a pro that uses safe cleaning methods. Many roofers won’t clean roofs, and some who do want to use pressure washing, which can damage the shingles if the water pressure is too great. Garden-type sprayers are usually used to apply cleaners, and most experts recommend rinsing the roof with a hose equipped with a nozzle that delivers a forceful stream of water.
If you are successful in finding a roof-cleaning pro in your area, find out what method of cleaning is used and make sure it is safe for your roof and plants before signing a contract. The roof cleaner should also have liability insurance and worker’s compensation for employees.
Q. A chunk broke off the side of my concrete driveway, and I tried to patch it with a good-quality patching cement. The patch looked fine for a while, but then it broke off at the same point where the original had broken. How can I make the patch stick?
A. Your best bet is to use a concrete bonder to help hold the patch in place. Bonders are liquids that are usually applied to the broken area with a paint brush, but they can also be mixed with the patching mixture.
Bonders can be bought in containers of various sizes at most home centers, hardware stores or on the Internet. Elmer’s and Sakrete are two well-known brands.
An alternative method is to drive several concrete nails partway into the broken surface, letting the nails protrude an inch or more. The nails grip the patch and help hold it in place. Concrete nails are very thick, strong nails that won’t bend if driven properly. It doesn’t matter if a few nails get bent, as long as they protrude enough to help grip the patch.
Q. I use a 24-foot extension ladder to clean my rain gutters and do other high work on my house. I have never felt really safe on it, and recently I came close to having an accident when it started to slide sideways. What can I do to improve safety?
A. There are several things you can do to improve the safety of the ladder, but you should keep in mind that ladders are basically dangerous and must always be used with extreme caution.
One good step is to equip the ladder with a stabilizer, a removable device that greatly increases the span of the ladder at the top. A stabilizer (sometimes called a standoff) is a U-shaped device that is bolted near the top of the ladder.
Stabilizers are normally about 4 feet wide and have padded feet to rest against a roof or siding without damaging them. This device not only makes it easier and safer to clean gutters, but it can also span windows to make it easier to paint, clean, caulk or make various repairs. A disadvantage is that a stabilizer makes a ladder slightly top-heavy and awkward to move.
You must still make sure your ladder is firmly planted at the base and that it is resting on a level surface. Since the ground around a building usually slopes or is uneven, there are several ways to level the ladder.
If the slope or unevenness is minor, you can use wood shims under the bottoms of the rails to keep the ladder perfectly vertical. This will help eliminate those very dangerous sideways slides. I keep a supply of shims in a cardboard box; they are flat pieces of wood that range in thickness from 1/4 inch to 1 1/2 inches. Each of the shims is large enough to give the ladder foot adequate support. However, I don’t recommend using shims on sharply sloping or very rough ground. If you use shims, you should also avoid stacking more than a couple of shims; too many shims will not be stable.
There are also ladders and retrofit attachments that bolt to the bottoms of the rails and can be adjusted to keep a ladder vertical on sloping or rough ground.
A third, very important, step is to make sure the base (rail bottoms) of an extension ladder is the correct distance from the building it is leaning against. A rule of thumb is that the base should be 1 foot away for every 4 feet of ladder height. Q. I plan to buy a chainsaw for occasional use on my property. I’ll mostly be sawing fallen limbs into firewood. Some limbs are up to 8 inches in diameter. Do you recommend a gasoline-powered or an electric chainsaw?
A. For occasional use, I would choose a good electric chainsaw. You need a three-pronged, grounded electrical outlet to plug it into, and the outlet should have a ground-fault circuit interrupter for extra shock protection. If you add a couple of heavy-duty, outdoor extension cords, you can use the saw 100 feet or more from the outlet.
The main reason I would go electric is convenience. All you need to do to use the saw is make sure it contains some bar-and-chain oil to lubricate the chain. A saw with automatic chain oiling is best — you won’t have to keep pushing a button with your thumb to oil it.
I’d get a saw with 16-inch bar — a good-quality saw with sharp chain can easily slice through 8-inch limbs.
Gasoline-powered saws are great for people who use them regularly — they are powerful and can be carried anywhere without reliance on electricity.
A downside is that gasoline chainsaws require a carefully prepared gas-oil mixture to operate. Another disadvantage is that gas saws are extremely noisy, much more than electric saws.
The fuel ratios vary, but a mixture of 40 parts gasoline to one part two-cycle engine oil is often used for gas-powered saws. Occasional users who mix too much fuel and then try to store it for later use often end up with stale fuel that makes the saw difficult, or impossible, to start. This can happen even if a fuel stabilizer, such as Sta-Bil, is added to the mixture.
I have used both gasoline and electric saws, and mixing small quantities of fuel that I could use within a reasonable time was quite a hassle.
Chainsaws of any type are much like ladders in that they are basically dangerous. When sawing, wear heavy gloves, safety glasses and noise-deadening earmuffs. Most saw manuals also recommend some special clothing, such as protective pants. Keep chainsaw blades sharp and at the correct tension for best and safest performance.
QUICK TIP I’ve heard from a couple of sources, including reader John Robertson, that a device called ThermaCELL is a first-rate mosquito repellent for areas like decks, patios or campsites.
ThermaCELL works by heating a small pad containing a chemical repellent, and is available in a couple of forms, including a lantern and what ThermaCELL calls an appliance, which is shaped something like a television remote control. Prices start at about $27.
I haven’t tried the ThermaCell, but it does seem to have staunch advocates. The ThermaCELL website ( www.thermacell.com), answers many questions, and also gives buying information. ThermaCELLs are also sold at some sporting-goods stores.