A lot of people on the East Coast and elsewhere are still dealing with the surprising ferocity of last winter. Storm after storm racked up foot after foot of snow, and while it's easy to see the cratered driveways, pot-holed streets, flattened shrubs and battered fences, some of the winter's worst damage may be out of sight -- on the roof.
You can almost bet that the snow and wind and ice that made walking from the house to the car a feat worthy of Roald Amundsen took a bite out of both shingled and built-up roofs. Even if your roof wasn't damaged by the weather, you should think now about doing some routine maintenance, or having a professional do it, to prevent problems in the future.
How you go about maintaining a roof depends on what it's made of and how steep it is. The two roof types common in most cities are "flat" built-up types laid in hot tar and steeper shingled roofs. Steepness is measured in inches of rise per horizontal foot of roof. For instance, "flat" roofs should have a pitch of no more than 3 in 12 (three inches of rise for every 12 inches). And shingle roofs work best at a pitch of four in 12 or higher.
Clearly working on a flat or low-pitched roof is easier than working on a steep roof. To work on a steep roof you need safety equipment, so if you slip, you don't go over the edge. Prices for restraining systems start at $65 for a body harness and go up to $300 for harness, rope and anchors. Thus working on a steep roof could require too large an equipment purchase for the average do-it-yourselfer. And there's another point: even harnessed, you need to be comfortable with heights. If you're not happy off the ground, stay off the roof.
As long as they're not damaged, fiberglass shingle roofs do not require as much periodic maintenance as flat roofs. When you install a new roof, be sure to squirrel away some extra shingles. If a tree falls and punctures the roof in a couple of places, or if the wind somehow whips off a few shingles, you can replace them fairly easily. Shingles are nailed in the top part about an inch above the section you can see. Each shingle is about 12 inches deep, with about five inches showing.
Use a pry bar (a flat metal tool with one curved end and one forked end) under the damaged shingle to pry up the nails. Remove the old shingle and clean up the space it occupied. Then put a couple of dollops of roof cement under the front half of the new shingle and slide it into place, lining it up with the bottom of the adjoining shingles.
Carefully pull up the top shingle or shingles and hold back gently (you'll need an assistant for this). Nail the new shingle to the roof about an inch above the part that's visible. Use galvanized roofing nails and make sure they are long enough to go into the wood sheathing.
Finally, put some cement on the bottom side of the top shingle(s) and gently pat back down over the new one.
A standard built-up roof, like that found on most Baltimore rowhouses, requires a hot-tar coating every three years. You should have gotten a 10-year guarantee when you had the roof installed; the guarantee is predicated on having the roof recoated at regular intervals. The hot-tar process is not one homeowners can generally tackle -- how many of us have a hot tar pot in the garage? There are "cold" method coatings that come in a can, but before you try that, check to make sure you are not voiding the guarantee by using the cold system.
If you just bought a house and don't know when the roof was installed or coated, you need to start your own maintenance record. Whatever the guarantee, you still need to check the roof periodically.
With either a flat roof or a shingle roof, a lot of leaks occur because the mortar leaks above the flashing at chimneys or adjoining roofs. It looks like a roof leak, but it's really a chimney or parapet wall problem. Windows are another source of pseudo-roof leaks, when water seeps in through damaged or missing caulk. You need to keep the mortar pointed up, and you need to caulk all windows. A homeowner who's at ease at the top of a ladder or walking on the roof can probably accomplish these tasks.
Flashing around roof protrusions also needs regular attention -- anywhere the roof meets another surface, pipe, chimney or wall. If a piece of metal flashing is loose or has a hole, secure it with roof cement or fill it with caulk.
If you get up to the roof and find widespread damage, schedule a visit from the roofer soon -- don't wait until leaks let you know there's something wrong. You may want to get right on this: Winter starts again Dec. 22, and that's only 225 days away.
Pub Date: 5/11/96