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The Boston Globe

Lifestyle

Handyman on Call

The mystery of the 22-year leak

Q. In cleaning out the attic while preparing to sell my 1939 Cape in Newton, I discovered way in the back three containers, one with water in it, (the others too far in the back for me to dare peek at) and a punky spot on a board nearby. The bottoms of some cardboard boxes in the area were damp too. The last time anyone was back that far in the attic, that I know of, was 22 years ago (1992) when skylights were installed.

My late husband and I had struggled with a persistent leak in the ceiling of the upstairs hall for many years, hiring several roofers to take a look. No one fixed it. But finally, one day, he told me that the leak was fixed at last. That was probably 15 years ago. Now I see that the “fix” was temporary, though it did put my mind at ease. In 2010, four years after my husband’s death, I had a new roof installed and a chimney cover put on as recommended by the contractor. No one ever mentioned a leak. I assume the problem was with the chimney flashing.

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My question: Should roof shingles be placed on top of the flashing, under it, or both? A new contractor said he may have to take off the chimney cover (a big white box that cost $960 in 2010) to find the leak at a cost of $2,000. I hope to get the leak fixed at last.

A. It might not be a leak all by itself, and I say get rid of the white elephant called a chimney cover; that is, if the chimney looks OK as it is. The other problem is condensation of water vapor in the attic. That part can be fixed by venting the attic with a ridge vent at the top of the roof and soffit vents in the roof overhang.

For your question: Chimney flashing generally goes on top of shingles. In other areas, such as roof edges, shingles go on top of flashing.

Q. We have a screened-in porch (about 14 by 12 feet) in the back of our house and every spring over the past several years I have had to clean it with bleach and water. I noticed mildew starting to reappear just a few months after cleaning it. The ceiling has a coat of oil-based prime. We did not put a final solid stain coat on it because that tended to bubble and chip periodically. The oil-based prime seems to hold out, except for the reappearing dark spots of mildew over ¾ of the ceiling (which is tongue and groove cedar boards, I think). The screens run from the floor to a 2½-foot overhang on three sides of the porch.

You suggested ventilation vents and maybe a ceiling fan but my roofer/contractor was adamant that it’s dead cold space above the screened porch and shouldn’t need ventilation. Do you have any added suggestions or contrasting opinions in dealing with this chronic mildew problem?

A. I was not as clear on ventilation as I should have been. The space between roof and ceiling is what needs venting. That can be done by putting in vents on those three overhangs. AND vent the roof where it butts into the house. Cut a 2- or 3-inch slot along the roof where it meets the house. Then cut the vent part of one side of the ridge vent, with the other side on the slot and the other half going up the house wall, under the siding.

Globe Handyman on Call also appears in the Sunday Address and Real Estate section. He is available 1-6 p.m. Tuesdays to answer questions on house repair. Call 617-929-2930. Contact him at photton@Globe.com.
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