Flashing is the term used for thin sheets of galvanized aluminum (sometimes copper) which are placed where shingles abut chimneys, skylights, the valley between intersecting roof sections and wall sections. Drip-edge flashing is used where shingles end at the edges of the fascia and gable ends. If the flashing begins to push up, due to swelling underneath on the shingles, it can be re-nailed gently in place. If the problem continues or can not be corrected this way, it will need to be replaced. Use nails of the same metal as the flashing if you nail it down. Different metals can cause corrosion.

Chimney flashing that is held in place by masonry cement or roofing tar will form gaps. Flashing for roof alleys and that which bridges the gap between shingles and vertical siding is held in place by the siding and seldom needs repair if it is not loose or visibly damaged. Plumbing and furnace vents are flashed with a one-piece collars with the base lying under the shingles. Check for any swelling under the flashing or raised edges on the shingles. Special flashing adheasives are available at most hardware stores.

Flashing leaks are covered in Section V of The Home Waterproofers Manual – Home Waterproofing A to Z. Remember, in the waterproofing business it’s “buyer beware”. Most salesmen get a percentage of the sale and don’t consider it their job to save you money. They charge as much as they can. If there’s a cheap way to fix the problem, they won’t mention it, but will only talk about preventing serious damage and try to scare you into signing a big contract.

You can save thousands of dollars and many headaches by learning what is going on first. Often what looks like an expensive and serious problem may not be. Once the problem is explained, solving it is just common sense. I’ve used the knowledge I’ve put in The Home Waterproofers Manual – Home Waterproofing A to Z every day to fix water problems. It will work for you too.

But remember, when dealing with salesmen, in the waterproofing business it’s “buyer beware”. Most get a percentage of the sale and don’t consider it their job to save you money. They charge as much as they can. If they see a problem that can be fixed at low cost, or one that has a simple solution, they won’t mention it, but will only talk about “preventing serious damage” and try to scare you into signing a big contract.