Replacing Roof Flashing

What You'll Need
Replacement flashing.
Metal brake
Tin Snips
Roofing nails
Replacement shingles
Pry bar
Roof cement

Roof flashing is the barrier between your home and the weather. Once you roof flashing fails, your roof will begin to leak water and cause major damage.

Periodically inspect your roof for any signs that the integrity of the structure has been compromised. If you see sagging, then it is too late you and you will have to replace a major portion of your roof. However, if you can catch a leak quickly, then you can make a quick repair.

Roof flashing replacement can be done with a few simple tools and techniques.

Remove Surrounding Shingles

Before you can get to the flashing that needs to be replaced, you will need to remove the shingles around the area. If you work carefully, you may not have to actually replace any shingles—you can keep the same ones.

Gently pry up the shingles around the flashing so you can remove them for use later. Try to slide the pry bar under the roofing nails and apply pressure, lifting the nail out.

Loosen Vinyl Siding

The flashing you need to replace might not be located on the actual roof valley. It could be the drip edge or a piece of flashing running up the corner of the house. If this is the case, gently loosen the siding around the area so you can get access to the flashing material.

Remove Old Flashing

Pry up the old flashing, taking care not to damage the underlayment or the other shingles. Scrape up the old roofing tar and replace any roof felt if needed.

Measure and Cut

Measure the length you will need for the new flashing. Transfer that measurement to the new flashing and cut with the tin snips. Wear gloves while cutting, and always hold the flashing on a stable surface.

It is not important to be exact. In fact, try to keep it a little long in case you make a mistake. It is better to have a long piece than a short piece.

Crimp the Flashing

Use the metal brake and bend the flashing lengthwis, into a 90-degree angle. If this is for a valley flashing replacement, then you do not need such a severe angle. Check the angle with a square and transfer to the brake.

Install Flashing

Lay the new flashing on the roof and nail down. Cover seams with roofing cement and smooth it out with a scraper.

Replace Shingles

Once the flashing is in place, you can replace the shingles you removed. Use roof cement along the edges of the shingles and the flashing to create a waterproof seal.