Q: An overhanging tree has been scraping my roof. How can I replace just a few shingles?

A: (from DIY home improvement expert, Brad Staggs) If your roof has had some limited shingle damage (figure A), it is possible to replace just one shingle or course of shingles. Here are some tips and suggestions.

a.

Shingle Basics: Asphalt shingles are installed in overlapping courses, and are commonly constructed as three-tab strips. Each strip is nailed at regular intervals -- corresponding with the tabs -- along it's length (figure B). The nails are placed in a sealing strip that's made into the strip. Since the courses of installed shingles overlap (figure C), when removing a section of shingle you'll need to remove the nails in the course you'll be replacing as well as those in the course above it.

b.

c.

1. Begin by using a pry-bar to gently lift the shingle tabs and break the seal ( figure D) so that you can access the nails underneath. Asphalt shingles can be brittle and may break easily, so use caution as you lift the shingle tabs so that you don't damage the shingles in the course above.

d.

2. Once the tabs have been lifted clear, use a hammer and "cat's paw" nail-puller to slide under the head of the roofing nail (figure E) and carefully pry it up to remove it (figure F). Repeat this process for each nail in the section of shingle.

e.

f.

3. With the nails removed, lift up and remove the damaged shingle (figure G)

g.

If the replacement strip is longer than the section you're replacing, you may need to cut off a portion of the strip. If you look closely, you'll notice that there are scored notches along the top edge of each shingle (figure H). You can use these scores as guides when you cut off a section of the shingle.
Important: If you need to cut shingles, and you are working on your roof, you'll need to lay down a protective surface (e.g., some spare shingle strips) on the area of roof where you're working. This will prevent you from accidentally cutting into your existing (installed) shingles.

h.

4. To cut the excess length of shingle away, use the straight edge of a framing square, locking it against the scored tab for stability. Then make a straight cut using a utility knife (figure I). It may take two or three passes with the blade to cut all the way through.

• Tip: Cutting through asphalt shingles is tough on cutting blades. Make certain you have plenty extra blades for your utility knife.

i.

5. To protect your roof sheathing, before you install the new shingle section, seal the holes where the nails have been removed using roof cement (figure J).

j.

6. Slide the new section of shingle in place (figure K), making sure it is even.

k.

7. Secure the new section with roofing nails (figure L) in roughly the same locations where the old nails were removed.

l.