Roof Flashing Shingles
Fix a Roof

Leaves and twigs that accumulate in the gutter will eventually clog the downspout opening and when that happens, the gutter overflows. Pick a dry day with little or no wind and use an extension ladder that reaches at least 2 feet above the gutter. Use an old whisk broom to sweep up all the leaves then scoop them into a pail with a garden trowel.
Now to prevent the clogging install leaf strainers that fit into the downspout openings to trap leaves. An even better solution would be to cover the entire length of gutter with mesh screens. These are made of metal or plastic and are also sold in hardward stores, these screens usually have molded edges or clips along the outer edge so you can snap them on over the outside rim of the gutter. The other edge of the screen slips up under the first row of roof shingles, allowing water to flow into the gutter, but keeps out the leaves.
I would suggest if you have holes, cracks or ruster-out sections that you use a heavy-duty patch in order to repair. Start by cleaning the metal thoroughly with paint thinner. Then use a putty knife to spread a liberal coat of asphalt roofing cement over the damaged area, spreading it out several inches beyond the actual hole. Cut a piece of heavyweight aluminum foil large enough to cover the cement and press it down, smoothing to eliminate air bubbles. Spread anotehr layer of cement over the foil to cover it 2 inches beyond the foil on all sides. searching for roof
I would also make another suggestion to avoid letting water from the downspout pour out onto the ground next to the house. The safest disposal method is to connect the downspout to an underground dry well at least 10 feet away from the foundation (make your own dry well with a 50 gallon drum filled with rocks). Or you could attach perforated plastic hoses or soakers to the bottom of the downspout. These are normally rolled up so they are out of the way. When it rains, however, the water coming out of the downspout unrolls them and allows water to seep out over the ground several feet away from the house.
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Roof Fixing - Tip for Repairing your roof - Getting a roofer - How to Check your roof - Further Resources