Roof Repair vs. Replacement: How to Decide

Should you repair or replace your roof?

Whether to repair or replace your roof comes down to three things: how widespread the problem is, how old the roof is, and the condition of the deck underneath. A roof that is mostly sound with one damaged area is usually a repair. A roof with wear across many slopes, repeated leaks or soft decking is usually a replacement. The harder cases sit in between, such as a 20-year-old asphalt roof with one storm-damaged slope, or a slate roof with failing flashing but sound stone. In those, it helps to get a clear diagnosis of what is causing the problem, a frank opinion on how long the rest of the roof will last, and a written scope for both options. Then you can weigh a repair now against the likelihood of more repairs soon.

When is a repair the right call?

A repair is the right call when the damage is contained and the roof around it still has good life left. Typical examples include a few shingles blown off in a nor'easter, cracked or loose flashing at a chimney or wall, a split vent boot, a single leak traced to one spot, or a stretch of fascia and drip edge damaged by ice. A good repair addresses the cause, not just the stain. If water came in at a chimney, the flashing needs attention, not a bead of caulk. If the leak came from an ice dam, the roofing may be fine and the real fix is in the attic. Ask your contractor to explain what failed and why. Keep in mind that matching older shingles can be difficult, so a repaired patch may look different from the rest of the roof.

When is replacement the better choice?

Replacement is the better choice when the surface is worn across large areas, leaks keep showing up in new places, the deck is rotted or sagging, or repairs would cover a large share of the roof. Curling and brittle shingles, heavy granule loss, many missing or cracked pieces and widespread moss are signs the material is near the end of its life. Age matters too. Repairs to an asphalt roof already near the end of its expected life often buy only a short reprieve, and each New England winter on a failing roof risks interior water damage. Replacement also makes sense when you're planning other work that affects the roof, such as an addition, a dormer, skylights, solar panels or attic insulation upgrades, so the roof and those projects can be coordinated.

Can you replace just part of a roof?

You can replace part of a roof, such as one slope, in some situations, but it comes with trade-offs. Partial replacement can make sense when one side of the house took storm damage or wears faster from sun exposure while the rest is in good condition. The new and old sections may not match in color or texture, and the transitions between them need careful flashing. If the rest of the roof is close to needing replacement anyway, doing it all at once usually gives a more uniform result and avoids a second round of setup, tear-off and disposal later. With a metal roof, ask how the new system will tie into any adjoining roofs that stay as they are, such as a porch or garage. Your contractor should explain how a partial job would be detailed and whether any warranty terms differ.

Should you roof over the old layer or tear off?

Tearing off the old roof is usually the better approach, and for some materials it is required. For an Interlock® roof, tear-off is mandatory over cedar shingles or shakes, concrete tile and natural slate, and a single layer of asphalt may be roofed over only if an inspection finds it suitable. Building codes also limit how many roofing layers a house may carry; your local building department can tell you the rules for your town. Tear-off lets the crew see the deck and replace rotted sheathing, which is common at the eaves of New England homes that have had ice dams. It also allows a fresh ice barrier membrane at the eaves and new flashing at walls and chimneys. A roof-over can mean less disruption, but only when the existing layer and deck are in good shape.

How do you choose a contractor for either job?

Choose a roofing contractor who is properly registered, insured and willing to explain the problem and the fix in writing. In Massachusetts, contractors doing residential work covered by the Home Improvement Contractor law (M.G.L. c. 142A) must be registered, which also gives eligible homeowners access to the Guaranty Fund. Connecticut requires home improvement contractor registration through the Department of Consumer Protection, and Rhode Island registers contractors through its Contractors' Registration and Licensing Board. New Hampshire and Maine have no state roofing license, so references and proof of insurance matter even more there. Ask for a written contract with the scope and materials, and details on warranties. On an Interlock® roof, the material is covered by the Guardian Lifetime Limited Material Warranty. Get a second opinion if the diagnosis is unclear.

Common questions