How to Trim Asphalt Shingles at the Edge of a Roof

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Things You'll Need

  • Yardstick

  • Blue chalk

  • Hook-blade knife

Image Credit: Jupiterimages/ Images

Careful edging marks the difference between an elegant, neat roof and a roof that makes your house look disheveled. When re-shingling the edge of your roof, you'll want to apply the new shingles and then trim them back to avoid waste or poor guessing. This task can be accomplished in a few hours using tools you should have around the house. If you don't have a hook-blade knife, don't try to do the job with a small saw or a pair of clippers. This knife will get you the crisp edges and clean cut your roof needs to look elegant.


Step 1

Inspect the roof line of your house. Is it straight across? Are there any gaps, buckled eaves or irregularities in this line? If so, you'll need to trim the shingles in a series of steps. If you have a flat line across the entire side, your job will be easier.

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Step 2

Hold a ruler or yardstick over your shingle 1/2-inch beyond the roof line. Handyman Ian Eltringham recommends leaving a 1/2-inch overlap between the edge of the roof and the shingle. rather than cutting the shingle at the roof's edge. Draw a blue chalk line at this line. When you cut along the chalk line, you should be making the shingles even and leaving a 1/2-inch overhang where the shingles extend beyond the edge of the roof.


Step 3

Extend the chalk line along all edges of the roof so that all of the guidelines will be marked before you begin.

Step 4

Cut along this line using a hook blade. Hook blades can be purchased at your local hardware store and are ideal for cutting through thick asphalt shingles with ease. Continue cutting away the excess shingle until your entire roof has been trimmed.


Blue chalk will rinse off of your shingles with water or rain. Red chalk will not reliably rinse away.

Save the scraps of shingle. If you lose shingles in a storm you may be able to patch the root with these scraps.

You can use a chalk line in place of a yardstick and blue chalk if you have one.


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