If your roof is leaking, shingle replacement may seem like a straightforward task. There are actually many steps and skills required for new shingles, which is why it's a job best left to the pros.

1. Teardown and Repairs

Shingle replacement nearly always begins with tearing off the old shingles down the plywood roof decking. Once this is complete, the decking and underlying roof structure are inspected for damage such as punctures, leaks, and wood rot. The eaves and ventilation systems on the roof will also be inspected for any problems. If damage is found, it must first be repaired before shingle replacement can continue. 

2. Flashing Replacement

New flashing is installed after repairs are completed but before the new shingles are put on. Most flashing is made of aluminum or a similar thin but durable material. It's installed around rooftop penetrations, such as vent stacks and chimneys, so that a watertight seal can be created between the penetration and the shingles. Flashing isn't always replace, but it will be if it is corroded, warped, or otherwise in poor condition.

3. Ice & Water Barriers

In most areas, an ice and water barrier is not only recommended, but required by code regulations. This is a thin material that is installed on top of the decking along the edge of the roof. The barrier is designed to protect the eaves and roof edges from any water or ice that backflows under the shingles at the roof edge, a common issue if there are clogged gutters or winter ice buildup along the eaves. 

4. Shingle Installation

Once the base structures of the roof are complete, the shingles can be installed. Asphalt shingles are installed individually, working up from the eaves toward the peak so the shingles overlap to create an overlapping and watertight membrane. Most shingles are installed along the top edge with nails, and then adhesives may be used on the lower edge to prevent them from lifting in windy weather. 

5. Finishing Work

Although shingle installation is the goal, it isn't the last task when it comes to shingle replacement. Finishing work must be done to ensure there are no leaks. Sealants are painted on over flashing and shingle seams, for example, to better waterproof these areas. Ridge caps and valley seals must also be applied where shingles meet at different angles. Your roofer may also take this time to replace vents in the eaves or along the roof ridge, if necessary.

Contact a roofer to learn more about shingle replacement.