Roof sealing is sold hard and understood poorly. The honest version is that it works well on some roofs, does nothing useful on others, and the difference is measured rather than guessed.
Two very different products
A film-forming sealer lays a skin over the shingles. A penetrating treatment works into the material instead. The first can peel, blister and trap moisture; the second has no film to fail.
Most of the bad reputation roof sealing has earned comes from the film-forming kind applied to the wrong roof.
Where sealing helps
On a roof that is structurally sound but drying out, a penetrating treatment restores flexibility and water repellency, and buys years of service without a tear-off.
It also helps where biological growth keeps returning, because a surface that sheds water is a poor place for algae and moss to settle.
Where it does not
An active leak, missing or blown-off shingles, soft decking, or damage around flashing are repair jobs. Sealing over them hides the symptom and traps the problem underneath.
A roof at the very end of its life is also the wrong candidate for a long warranty. A bridge treatment may buy time while you plan a replacement, and that is a different purchase.
Questions worth asking
Is the product penetrating or film-forming? Is there a written manufacturer warranty, and is it prorated? Does the price include cleaning and minor repairs, or are they extra?
A treatment sold without an assessment of the roof is being sold on hope. The score is what makes the recommendation honest.
Source
Written for Dr. Armor. The original GoNano article this guide draws on: The pros and cons of roof sealing treatment
Questions
Common questions, answered in full
- How long does roof rejuvenation last?Coverage runs from 3 to 20 years, and the roof’s condition score decides which.
- Can you treat a roof that is leaking?No. A leak is a repair job and has to be fixed before any treatment.
- What does the warranty cover?Peeling, curling or warping caused by the treatment, and water getting through.