Here's How: Tips for Replacing a Shingle Roof

James Dulley on Jun 19, 2025

Dear James: When we have a strong rain, I notice some leaks through my garage's 25-year-old shingle roof. What are some tips to replacing the shingle roof myself? -- Tonya D.

Dear Tonya: It actually is surprising that you are just starting to notice some leaks from a 25-year-old garage roof. Garage roofs often deteriorate faster because builders don't always install adequate attic ventilation over the garage like they do over the living areas. Without enough ventilation, the shingles get excessively hot in the summer sun, which shortens their life.

With a roof that old, it does make sense to reroof the entire garage rather than just sealing a few shingles each time a new leak forms. In order make repairs properly, you will have to disturb the other shingles around the repair spot. Most likely you will damage the good shingles and just end up creating worse leakage than you already have.

Installing shingles over an existing roof might appear to be a major undertaking, but it is really quite a simple job that most do-it-yourselfers can handle. If the old shingles are not badly curled on the edges, you should be able to place the new shingle over the old ones.

If the old ones are curled, you will have to tear off the old shingles first. This is a time-consuming task requiring a reasonable amount of strength, and you should leave it up to the professionals. It would take you quite a while to tear the old shingles off, leaving your roof totally exposed if it should rain. A roofing contractor can bring in a crew and do it quickly.

Whenever working on your roof, safety should be your first consideration. Always work with a helper or let someone know that you are working on the roof. It's a good idea to take your cellphone or cordless phone with you. It is possible to slip or get in to an awkward position and require help.

Wear soft-soled shoes, and never work on a wet roof. Be careful of the early morning dew. Go to a mountain-climbing outfitting store and get some high-quality rope, harness and repelling gear (which will probably total about $100). Tie the rope to the chimney or a tree. If you slip, you can safely lower yourself to the ground with it.

The basic concept of roofing is very simple. Each shingle overlaps the lower shingle so that the water runs off the roof. With the roof pitch, the water will not back up under the shingles under normal conditions. Adhesive on the shingles causes them to fuse together after a short time of exposure to the hot sun.

You can find many books with all the specifics of reroofing a house, but here are a few tips to keep in mind. Pay particular attention to the flashing where the garage roof meets the house wall, chimney, etc. Use ample roofing cement in those locations.

Always snap chalk lines to keep your shingle lines straight. People often think that they can just eyeball a straight line, and the result is an amateur-looking job. Make sure to use the recommended shingle exposure width to provide adequate shingle overlap.

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Send your questions to Here's How, 6906 Royalgreen Dr., Cincinnati, Ohio, 45244 or visit www.dulley.com. To find out more about James Dulley and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.