Repair vs. Replace: How to Decide on Your Roof

It is the question every island homeowner faces eventually: patch the roof one more time, or bite the bullet and replace it? Get it wrong in either direction and you lose money — pouring cash into a roof that is beyond saving, or tearing off one that had a decade left. This guide gives you a clear framework for deciding, calibrated to the specific realities of roofing in the San Juan Islands.

Start With Three Questions

Before you look at a single estimate, answer these. They resolve most cases on their own.

1. How old is the roof?

Age is the strongest single signal. Asphalt shingles on an island typically last 15 to 25 years, less if moss has been neglected. Standing-seam metal can run 50 years or more. If your asphalt roof is past 20 and giving you trouble, you are usually replacing. If it is 8 years old with one leak, you are almost certainly repairing.

2. How widespread is the damage?

A single leak at a flashing detail is a repair. Water showing up in several places, sagging areas, or daylight through the deck point to systemic failure. Localized problems get fixed; widespread ones get replaced.

3. What condition is the deck in?

If the wood decking beneath the roofing is rotted or soft — a real risk after years of moss holding moisture on shaded north slopes — patching the surface solves nothing. Deck rot almost always tips the decision toward replacement.

The Decision Table

Use this to place your situation. Ranges are an estimate, not a quote, and reflect island pricing including ferry logistics — crew and material staging plus off-island disposal — which add roughly 10 to 25 percent over a comparable mainland job.

Situation Repair Replace Estimated Cost One isolated leak, roof under 15 yrs ✔ $450 – $3,500 Moss present, no deck damage yet ✔ (treat) $400 – $1,600 Multiple leaks, roof 20+ yrs ✔ $11,000 – $40,000+ Rotted or sagging deck ✔ $11,000 – $40,000+ Failing flashing, sound roof ✔ $450 – $3,500 Frequent repairs, rising cost ✔ Asphalt $9k–$24k / Metal $14k–$45k+ Flat section, aging membrane ✔ or ✔ $8,000 – $26,000

When Repair Is the Right Call

Repair wins when the roof is fundamentally sound and the problem is contained. Classic repair situations on island homes include:

• A leak traced to worn flashing around a chimney, skylight, or vent.
• Wind damage on the west side that lifted or tore a small area — island wind runs roughly 20 percent stronger than Anacortes, so localized wind damage is common.
• A cracked valley or a few displaced shingles.
• Moss that has taken hold but not yet rotted the deck.

In these cases a targeted repair, plus preventive steps like ice-and-water membrane at the fixed valley and zinc or copper ridge strips to slow moss, buys you years at a fraction of replacement cost.

When Replacement Is the Right Call

Replacement wins when repairs are chasing a losing battle. Signs it is time:

• The roof is at or past its expected lifespan.
• You are repairing the same roof year after year, and the costs are climbing.
• Leaks appear in multiple, unrelated locations.
• The deck is soft, sagging, or rotted.
• Granules are washing into the gutters in quantity, or shingles are curling across whole slopes.

Think in cost-per-year, not sticker price

A $2,500 repair that buys two years costs you $1,250 a year. A $28,000 standing-seam metal roof that lasts 50 years costs $560 a year — and it is the best long-term island roof, resisting salt air, wind, and moss when built right. When you find yourself repeatedly repairing an old roof, the "cheaper" repair is often the more expensive choice over time.

Island-Specific Factors That Tip the Balance

A few things weigh more heavily here than on the mainland:

• Salt air. Near saltwater, corrosion attacks cheap fasteners and coatings. If a repair means matching an aging, already-corroding system, replacement with 24-gauge marine-grade metal and PVDF (Kynar 500) coating may make more sense sooner.
• Ferry logistics. Mobilizing a crew and staging materials on-island carries fixed costs. If you are going to pay to get a crew out for major work anyway, doing the job once and completely often beats repeated trips.
• Moss and rain. With 40 inches of rain a year and heavy November downpours, a marginal roof degrades fast. Deferring replacement on a failing roof risks deck rot that raises the eventual cost.

Homeowners weighing these factors and searching for guidance on https://dallaspjxf852.talesignal.com/posts/how-to-find-and-fix-a-roof-leak should get a professional inspection before deciding — the deck condition in particular is hard to judge from the ground, and it frequently settles the question.

A Simple Rule of Thumb

If your roof is young and the damage is localized, repair. If your roof is old and the damage is widespread — or the deck is compromised — replace. When you are genuinely on the fence, weigh cost-per-year and the island's harsh conditions, both of which tend to favor doing the job right rather than patching indefinitely.

The Bottom Line

There is no universal answer, but there is a reliable method: assess age, extent of damage, and deck condition; place yourself on the decision table; then think in cost-per-year rather than sticker shock. Do that honestly, factor in salt, wind, moss, and ferry logistics, and you will spend your roofing dollars where they actually protect your home.

About the Author

Nathan Prewitt is a Salish Sea building inspector who has evaluated hundreds of roofs on the question of repair versus replacement. He specializes in helping island homeowners read the true condition of an aging roof before they commit to a decision.