Should I coat my roof or replace it?
Coat the roof if the shingles are worn but intact; replace it if they have failed. A nano coating restores and protects material that is still doing its job. It cannot put back a shingle that has lost its mat, dry out a rotted deck or close a hole that water is already coming through.
We see Ottawa homeowners quoted for a full tear-off on a roof with years left in it, and we see roofs treated that should have come off.
What makes a roof a strong candidate for coating?
A strong candidate is a roof that is losing its surface but has not lost its structure. Look from the ground, with binoculars if you have them, and from inside the attic.
- Shingles still lie flat. Edges and corners sit down against the course below rather than lifting away from it.
- Colour has faded but the surface is continuous. Dull, chalky or patchy colour is a surface problem, which is what coatings are for.
- Granules are thinning, not gone. Some grit in the eavestrough after a heavy rain is normal wear. Bare black asphalt showing through in patches is not.
- No active leaks. No staining on attic sheathing, no damp insulation, no ceiling marks.
- The deck feels solid. No sag between rafters, no soft spots, no daylight through the sheathing from the attic.
- One layer of shingles. That keeps replacement genuinely open later, which is what a coating buys you time for.
At the free on-site assessment we get on the roof, check its condition and photograph it.
When is roof replacement the right call?
Replace the roof when the shingles have stopped being a weather barrier. Any one of these findings on its own is usually enough for us to tell you to get replacement quotes.
- Structural deck damage. Sagging between rafters, spongy sheathing underfoot, rot around chimneys or valleys. The problem is under the shingles, so treating them changes nothing.
- Widespread cracking or curling. Isolated curling at a hot south-facing edge is one thing. Cracking and cupping across whole slopes means the asphalt has lost its oils and the shingles are brittle.
- Missing or blown-off shingles in several areas. The fasteners and the mat are failing, not just the surface.
- Active leaks at more than one point. A single flashing leak is a repair. Several separate leak paths mean the assembly is done.
- Bare mat showing. With the granules gone, the asphalt is exposed to UV and degrading fast. Nothing applied on top reverses that.
- Two or more existing layers. The deck is already carrying more weight and heat than it was built for, and the original layer cannot be assessed from above.
Coating a roof in this condition spends money that should go toward the replacement you need anyway. A coating delays replacement on a sound roof. It does not cancel it on one that has failed.
Which option matches my shingle age and condition?
Age narrows the product choice; condition decides whether coating is possible at all. Here is how we match the three roof products to your roof.
| Shingle age | What you are seeing | Usual answer |
|---|---|---|
| Under 5 years | Sound, full granule coverage, no visible wear | GoNano NuRoof Fortify. Protection applied before damage starts. |
| 6 to 20 years | Faded colour, some granule loss, shingles still flat and sealed | GoNano NuRoof Revive. Penetrates deep into the shingle to rebuild flexibility and reinforce structure. |
| Generally 15 years or older | Weathered and dull but intact, no leaks, deck solid | GoNano NuRoof Boost. For older roofs that no longer score high enough for Fortify or Revive. Suitability is decided by the Roof Health Score GoNano assigns your roof at the assessment. |
| Any age | Missing shingles, bare mat, widespread cracking, multiple leaks, soft deck, or two existing layers | Replacement. Coating is not an option and no assessment will change that. |
Not sure what a symptom on your roof means? The guide on curling shingles and granule loss works through the signs one at a time.
How much life does each option actually add?
A coating adds years to the roof you already have; a replacement starts a new roof's service life from zero. They are different purchases.
- GoNano NuRoof Fortify: up to 20 years of added roof life.
- GoNano NuRoof Revive: up to 12 years of added roof life.
- GoNano NuRoof Boost: up to 10 years of added functional roof life on a full treatment.
- Replacement: a full new service life, plus the shingle manufacturer's own warranty on new material.
Every one of those numbers is "up to": what the product can add to a roof in good condition, not a promise on every roof. The warranty is a separate, shorter term, covered below.
A GoNano treatment is a single application, not an annual maintenance product. Have the roof reassessed every 10 to 15 years to decide whether a retreatment is worthwhile.
How disruptive is each option, and how long does it take?
A coating goes on in one day with nothing removed from your house; a replacement is a multi-day job that strips the roof to the deck.
With a coating there is no tear-off: no dumpster on the driveway, no nails in the lawn and no exposed deck overnight for weather to get into. The sequence is the free assessment, then cleaning and any minor repairs, then application. A replacement opens the roof, which means scheduling around the forecast, protecting landscaping and living with a full crew for several days.
Coatings need surfaces that are dry and above freezing, so the Ottawa season runs from spring melt to the first hard frost, and the shoulder weeks book out first. Decide in November and you are usually deciding for next spring, so book the assessment early.
What does an Ottawa winter do to an aging shingle roof?
Two things do the damage: freeze-thaw cycling works water into shingles that have gone brittle, and ice damming holds standing water against the eaves where it has time to find a way in. Both get worse as shingles age.
An aging shingle has lost oils and granules, so it absorbs water instead of shedding it. That water freezes, expands and opens the crack a little further, through every freeze and every thaw. By March a shingle that started the season merely faded can be cracked. Meanwhile snow melting off a warm upper roof refreezes at the cold eave, builds a dam and backs meltwater up under the courses.
Act in the year you first notice the wear. The coating we apply leaves the surface water-repellent, so water beads and runs off instead of soaking in. It works on a shingle that is still whole. Once the cracks are open, you are in the replacement column.
What happens to warranties, resale and insurance?
Ask your shingle maker whether a field-applied treatment affects your shingle warranty, because the shingle makers' trade association advises exactly that. GoNano's own position, from a legal review by its law firm, is that the treatment does not void the warranties of IKO, Owens Corning, BP or GAF, and we can walk you through it at the assessment. Separately, GoNano issues a manufacturer's warranty of 3 to 20 years. The term depends on the Roof Health Score GoNano assigns your roof at the assessment and on the number of coats applied.
On resale, the GoNano warranty can be transferred once, with written notice to GoNano within 30 days of the sale. Be straight with a buyer: a coating keeps a serviceable roof serviceable. It does not change the age of the shingles, and a home inspector will record that age from the roof itself.
On insurance, some insurers recognise a coating and some do not, and we do not speak for them, so ask yours directly. If it helps the conversation, under UL 2218 impact testing one treatment takes a Class 1 shingle to Class 3, and two treatments take it to Class 4. How many coats your roof gets is specified at the assessment.
What determines the price of each option?
Published Ontario roofing price guides put a shingle replacement at $8,000 to $20,000 CAD in 2026. That is not a Protexa price. A treatment on a roof that qualifies is typically a fraction of it, fixed in writing after a free assessment.
Both options are priced off the same facts about your roof, which is why we will not quote either one from a photograph: size and pitch, shingle condition and granule loss, safe access, the prep and minor repair needed, and which product tier the roof calls for. A steep roof costs more to work on safely than a walkable one, and any flashing work before a coating is part of the job.
A replacement adds tear-off, disposal, underlayment and any deck repair that only shows once the old shingles are off, which is why replacement quotes so often move after the roof is opened. The guide to what determines coating cost covers each driver in detail.
The assessment carries no obligation and is available across Ottawa, Kanata, Nepean, Barrhaven, Orleans, Gloucester and Stittsville. Book the free on-site assessment and you will have a written number and photographs of your roof to decide from.
The short version
If your shingles are worn but whole, lying flat, holding granules and sitting over a solid deck, coating is very likely the better use of your money. If shingles are missing, cracked across whole slopes, worn to the mat, leaking in several places, or sitting on a soft deck or a second layer, replace the roof and do not let anyone tell you a coating will fix it. Everything in between is what we look at during the free assessment.
For how the products are applied, see the roof nano coating service page. If your roof is in the weathered middle of that range, see shingle restoration with NuRoof Revive.