If you own a triple-decker in Somerville or a 1920s colonial in Cambridge, the signs you need a new roof look different from what most roofing blogs describe. Flat rubber membranes, slate tiles, plank sheathing, balloon-framed walls, and a century of freeze-thaw cycles all change the rules. This guide walks through what to check, what the damage actually means, and when it makes sense to repair instead of replace. No pressure, no scare tactics. Just the same diagnostic we use on roofs across Greater Boston every week.
Start From the Ground: What You Can See Without Climbing
Most of the early warning signs you need a new roof are visible from the sidewalk or a second-floor window. You do not need to climb. Walk around the house in good daylight and look for shingle patterns that stand out, dark patches, and anything bent or lifted. On a triple-decker, step back far enough to see the full roof slope and the parapet walls at the front and back.
Things worth flagging:
- Curling or cupping shingles. The edges lift up or the center dips. Both mean the asphalt has lost its flexibility.
- Missing shingles. Often shows as a bare patch with lighter-colored felt or synthetic underlayment showing through. Common after a nor’easter.
- Dark streaks or green patches. Algae and moss hold moisture against the shingle and shorten its life.
- Visible sagging along a ridge line or between rafters. This is structural, not cosmetic.
- Flashing that looks rusty, cracked, or lifted around chimneys, skylights, and vent pipes.
On Somerville triple-deckers we often see missing shingles concentrated on the north-facing slope and around the chimney. That is where ice sits longest and where flashing gets pounded by runoff the most.
Check Your Gutters After a Storm
Granule loss is the sign most homeowners miss. Asphalt shingles are coated with small mineral granules that protect the asphalt below from UV. When a shingle gets old, those granules wash off into the gutters. A handful of grit after installation is normal. Piles of it after every rain mean the shingles are near the end of their service life.
Scoop out a gutter section in spring. If the sludge at the bottom looks like wet sand and you can rub off a dark gray dust on your fingers, that is asphalt granules. Some granule shed in the first year or two after install is normal, those are loose granules, not the bonded surface coat. On a roof under 10 years old with heavy shedding, the cause is usually a manufacturing defect, storm damage, or careless installation. On a roof 15 years or older, it usually means the surface is giving up.
Go Into the Attic With a Flashlight
The interior tells you what the exterior is hiding. Head up to the attic on a sunny day with the lights off. Here is what to look for:
- Daylight coming through the roof deck. Any pinhole of light is a hole water can follow.
- Dark brown or black water stains on the rafters or the underside of the roof boards. Fresh stains are soft and damp. Old stains are dry but still tell you the roof has leaked.
- Mold or musty smell. Often concentrated near the eaves or under valleys.
- Sagging decking between rafters. Push up gently with a gloved hand. Soft, spongy plywood or boards means rot.
- Insulation that is wet, matted, or discolored. Once insulation is saturated, it stays wet and feeds rot.
In older Somerville homes we find the worst attic damage in two places: right behind the chimney where old flashing has failed, and along the eave where ice dams have backed water under the shingles.
Ice Dam Damage: The New England Pattern
Ice dams form when heat escapes the attic, melts snow on the upper roof, and the water refreezes at the cold eave. The ridge of ice traps more meltwater behind it, which then finds its way under the shingles. By the time you see the icicles, water may already be inside the wall.
A new roof alone will not stop ice dams. The permanent fix is air sealing the attic floor, insulating to R-49 or better, and making sure soffit and ridge vents are clear and balanced. Any roofer who says a tear-off will solve your ice dams without discussing the attic is selling you the wrong job.
Watch Out: Never climb on an icy roof to chip at an ice dam. Every winter, Boston-area ERs treat homeowners who fell trying this. If ice is backing up water into your ceiling, call a pro with a steam machine. A roof rake used gently from the ground, on the bottom 3 to 4 feet of pitched slopes only, can reduce snow load without tearing shingles. On flat triple-decker roofs a rake does nothing.
Signs ice dams have reached the point where a new roof is on the table:
- Water stains that return every February in the same spot on a ceiling or top-floor wall.
- Peeling paint on the underside of an overhang or soffit.
- Shingles at the eave that are lifted, cracked, or missing after the melt.
- Visible rot on the fascia board.
One ice dam season usually will not kill a healthy roof. Five or six in a row on a 20-year-old asphalt roof often will. More on ice dam physics and prevention in the Boston.com ice dam guide.
Flat Rubber Roofs on Triple-Deckers: A Different Checklist
Most Somerville and Cambridge triple-deckers have a flat or low-slope roof covered in EPDM rubber or modified bitumen. These need a completely different diagnostic. On a flat roof the warning signs are:
- Ponding water still sitting 48 hours after the rain stops in dry weather. That is the NRCA industry threshold, and the point where many manufacturer warranties are voided. Puddles that do not drain point to either a clogged scupper or sagging decking.
- Bubbles or blisters in the rubber membrane. Once the seal breaks, water gets under the rubber and the roof fails from below.
- Cracks along parapet walls or at the edge where the rubber meets the wall. These let water into the top-floor ceiling.
- Seams that are lifting or peeling. EPDM seams, whether seam tape or older liquid adhesive, lose bond over the last third of the roof’s life. Lifting seams on a 15-plus year EPDM roof usually means you are close to the end.
- Drain or scupper blockage. A clogged scupper turns the whole roof into a pond.
On triple-deckers we also see parapet wall cracks that look harmless from the street but let freeze-thaw water right into the brick or wood structure behind them. That one is worth a closer look every spring.
How Long Should Your Roof Actually Last?
Age alone does not mean a roof needs replacement, but it tells you where to set your expectations. Material matters more than most homeowners realize.
| Material | Typical Life | Common on |
|---|---|---|
| 3-tab asphalt shingle | 12-18 years | Older colonials, ranches |
| Architectural asphalt shingle | 22-30 years | Most current installs |
| EPDM rubber (flat) | 15-25 years | Triple-deckers, flat-roof additions |
| Modified bitumen (flat) | 20-25 years | Older triple-decker flats |
| Slate | 75-100+ years | Victorian and turn-of-century homes |
| Standing seam metal | 40-60 years | Modern rebuilds, porches, dormers |
Slate is the outlier. Top-tier Vermont or Buckingham slate can hit 150 years. Softer Pennsylvania slate tops out closer to 75 to 100. We have worked on Cambridge homes with original slate over 110 years old that is still doing the job. Usually the slate itself is fine and the flashing is the problem. Replacing the copper flashing and a handful of cracked tiles is often the right call, not ripping the whole roof off.
Repair or Replace? A Plain-English Rule
A repair makes sense when damage is localized, the rest of the roof is under 75 percent of its expected life, and the deck underneath is still sound. A replacement makes sense when any of these are true: the roof is past its rated life, you are finding leaks in multiple spots, the decking is rotted, or your insurer has flagged storm damage across a large area.
One rough guide we share with homeowners on the fence: if a repair runs more than about a third of a full replacement, and the roof is past the halfway point of its rated life, replacement usually wins on cost per remaining year. Under halfway life with sound decking, repairs often make sense even above that ratio.
Pro Tip: Before getting quotes, take dated photos of every warning sign you found. Insurance adjusters and roofers both move faster when you can show them exactly what you are worried about. It also helps later if a storm claim comes into play.
What to Ask a Roofer Before Hiring
The biggest mistake we see homeowners make is picking a roofer on price alone. A cheap tear-off done badly will cost you the whole roof again inside a decade. Before you sign anything, ask:
- Are you licensed and insured in Massachusetts? HIC (Home Improvement Contractor) registration is mandatory for any residential exterior work. A CSL (Construction Supervisor License) is required when the job touches structural elements like replacing rotted decking or modifying the roof structure. For a straight re-roof on sound decking, HIC alone can be compliant, but you want a crew with CSL access in case decking surprises come up. Both are public records through the MA Division of Occupational Licensure.
- Do you pull the permit or do I? The answer should be them. In Massachusetts, pulling your own permit on HIC work waives your access to the state Guaranty Fund, so you lose a real financial protection if the job goes bad.
- Who does the work, your crew or a sub? Neither is wrong, but you want to know.
- What underlayment and ice-and-water shield are you using at the eaves? Massachusetts code requires ice-and-water shield from the eave to at least 24 inches inside the warm wall line. Many New England roofers go further, running two courses (about 6 feet up-slope) on vulnerable eaves. Ask what they spec and why.
- Warranty terms in writing. Manufacturer warranty on materials is standard. Labor warranty separates a real roofer from a flip.
On a triple-decker, add one more question: have you worked on flat rubber roofs and parapet walls before? The detailing is not the same as pitched asphalt. Experience matters.
When the Signs Add Up, the Next Step Is Usually a Free Look
Most of the damage we catch on Somerville and Cambridge roofs is small enough to fix if homeowners call early. The roofs that turn into full replacements are almost always ones where an easy signal got ignored for three or four winters.
We have been working on Greater Boston roofs, including triple-decker flats, slate, and every generation of asphalt, for over 20 years. If you noticed something from this list and want a straight answer on whether it is a repair or a replacement, we are glad to take a look. No sales pitch, no pressure. You get an honest read on what is happening up there. Learn more about our approach on the roofing services page, or reach out directly below.
Bastos Construction Group Inc
617-510-9251 | Contact Bastos Construction
