What a Full Roof Replacement Includes: Layer by Layer

1. Tear-off and protecting the property

A full replacement starts by stripping the old shingles, underlayment and nails down to the wood deck. Massachusetts follows the residential building code, which allows no more than two layers of shingles, so a roof that already has two must come off completely. Before tear-off the crew should cover shrubs, protect windows and siding, and set up a dumpster or trailer close to the house.

Many older Springfield, Chicopee and Holyoke houses have several layers or old wood shingles underneath, which adds time and debris. Ask how many layers the roofer expects to remove.

2. Inspecting and replacing decking

With the old roof gone, soft, rotted or delaminated boards become visible. These are cut out and replaced before anything new goes down. Pre-war houses often have plank decking with gaps between boards; some products call for a layer of plywood or OSB over planks. Because nobody can see the deck before tear-off, a good contract explains how replacement decking will be handled and approved.

3. Ice and water barrier

In western Massachusetts the code calls for a self-adhering ice barrier at the eaves, running from the edge of the roof to at least 24 inches inside the heated wall line. On a deep overhang or a low-pitch roof that can mean two or more rows. Most crews also run it in valleys and around chimneys, skylights and walls. It is the main defense against ice dams.

4. Underlayment

The rest of the deck is covered with underlayment, usually a synthetic sheet today rather than felt paper. It is a second line of protection under the shingles and keeps the deck dry if weather turns during the job.

5. Drip edge and starter course

Metal drip edge runs along the eaves and rakes so water drips clear of the fascia instead of soaking it. The code requires it on asphalt shingle roofs. A starter strip at the eaves and rakes gives the first course of shingles something to seal to, which matters in the wind that comes down the Connecticut River valley.

6. Flashing

Flashing is the metal that seals the joints where the roof meets something else: chimneys, sidewalls, dormers, skylights and plumbing vents. Old flashing that is rusted, bent or buried in tar is a common leak source and should be replaced rather than reused. Chimneys usually get step flashing plus counter-flashing cut into the mortar. New pipe boots go on every plumbing vent.

7. Shingles, ridge and ventilation

Shingles go on in courses following the maker's nailing pattern, with ridge cap shingles at the peaks. A replacement is also the easiest time to fix attic airflow: a continuous ridge vent at the top, clear soffit vents at the bottom, and old box vents closed off so they do not compete. Poor ventilation shortens shingle life and feeds winter condensation.

8. Cleanup and final inspection

Expect a magnetic sweep of the yard and driveway for nails, gutters cleared of debris, and the dumpster removed. In Massachusetts the building department usually does a final inspection on the permit; keep the sign-off with your house records. See permits and licenses.

Comparing two proposals

When two contractors describe the same roof differently, line them up item by item:

• Full tear-off, and how many layers
• How replacement decking is handled and approved
• How far the ice barrier runs, and where else it goes
• Type of underlayment
• New drip edge, flashing and pipe boots, or reused
• Ventilation changes
• Shingle product line and color
• Permit, inspection and cleanup responsibilities