This is the question that stalls the most decisions, and the one with the most convenient answers floating around. Here are the texts themselves.
What the warranties literally say
BP Canada excludes "any exposure to paint, inadequate cleaning solutions, coatings, chemicals, atmospheric or liquid, any application of the above products, any modifications of any nature whatsoever."
IKO, at clause 8.B of its Canadian limited warranty, excludes "the effects of chemical reactions with the shingles or chemicals applied to the shingles."
These are broad exclusions. They do not name nanotechnology treatments, but they cover the general category of products applied after installation.
The manufacturers' association position
The Asphalt Roofing Manufacturers Association (ARMA) is explicit in its technical bulletin: it strongly advises against applying any field-applied coating over installed asphalt shingles. Three risks are cited: creating a vapour barrier that can rot the deck, possibly altering the fire rating, and granule detachment.
One important nuance, however: that bulletin addresses coatings, film-forming products that sit on the surface. ARMA has not published a separate formal position on penetrating treatments, which work differently. The ambiguity is real, and we are not going to pretend it is settled.
The Quebec legal argument, and its limits
Several Quebec applicators argue that under the Consumer Protection Act, a manufacturer cannot void a warranty because a third-party product was used. The argument rests on the legal warranty, which genuinely exists.
What is accurate: in Quebec, the legal warranty under sections 37 and 38 of the CPA applies independently of any contractual warranty. It requires goods to serve their normal use for a reasonable time, and a merchant cannot contract out of it. A manufacturer therefore cannot make you waive your legal rights.
What is less accurate: that legal warranty does not automatically neutralise an exclusion clause in a contractual warranty. These are two distinct regimes. We found no published ruling and no Office de la protection du consommateur position confirming the broad reading some sellers give it.
Presenting that argument as an absolute green light goes further than known law supports.
What this means for you, concretely
- If your roof is under 10 years old and an active manufacturer warranty has real value to you, the question is worth putting to the manufacturer directly before any treatment. Write to them. Keep the answer.
- If your roof is over 15 years old, the manufacturer warranty is often already heavily prorated, or exhausted for labour. The practical stake drops sharply.
- In every case, Quebec's legal warranty continues to protect you against a latent defect or abnormally short durability, an independent safety net.
- Ask for the applicator's warranty in writing: duration, what is covered, what is not, and whether it transfers to a buyer.
A seller who tells you flatly that "the warranty cannot be voided in Quebec" is giving you half an answer. A seller who explains the tension between the two regimes is giving you something to decide with.
And home insurance?
That is a separate subject, and often more decisive. To our knowledge, no Quebec insurer has published a position excluding surface treatments. On the other hand, Intact has revised its roof underwriting: standard coverage on asphalt shingle is capped at 20 years, with an exclusion endorsement beyond that carrying a $5,000 deductible for water intrusion and no coverage for damage to the roof itself. One year's notice is given.
For an owner whose roof is nearing 20 years, that reality often weighs more than the manufacturer's warranty.
How we handle it
We raise this at the inspection, before talking price. If your manufacturer warranty is active and you value it, we suggest writing to the manufacturer and waiting for their answer. A sale delayed two weeks beats a customer who learns the nuance afterward.