How to: Roofing Over an Existing Roof

Your home's roof plays both functional and aesthetic roles: It keeps moisture from entering and improves the home's curb appeal. Replacing it can get expensive. Laying new shingles over existing shingles can substantially cut the cost of reroofing your house though. It eliminates the cost of tearing off the old shingles and of adding new roofing felt. If done correctly, you won't, without close inspection, be able to tell that your home has a double roof. You should, however, check with your municipal building department before adding the second roof; it may be a code violation.

Ladder
Hammer or nail gun
Roofing nails
Utility knife
Shingles
Ridge vent

Instructions

- 1
  Pull the ridge vent from the peak of the roof. Don't worry if you rip it or if nails won't come out -- you'll replace it with a new vent after laying the new shingles. Toss the vent off the roof. Check the flashing around pipes, chimneys or other protrusions, and repair or replace them if necessary.
- 2
  Lay a row of shingles along the length of the lower edge of the roof by driving three roofing nails through the each shingle. Lay the first and last shingles of the row so that their ends extend two inches over the edge of the roof; this helps with runoff.
- 3
  Lay each subsequent row so that it overlaps the upper half of the previous row, covering the nails and nailing tabs. Continue installing shingles until the entire roof is covered. Unroll the new ridge vent, nailing it into place as you go.

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