Roofing guide

Roof Coatings in Alaska: What They Can and Can't Do

Last updated November 2, 2026

Roof coatings are liquid-applied membranes used mostly on low-slope roofs and metal roofs. Applied to a sound roof, they can seal minor leaks, reflect sunlight and extend service life. They are not a fix for a roof with wet insulation, rotten decking, structural problems, or the heat loss that causes ice dams.

Which roofs are good candidates for a coating?

The best candidates are low-slope (nearly flat) roofs and metal roofs that are structurally sound, mostly dry underneath, and showing surface aging, minor leaks at seams or fasteners, or rust that hasn't perforated the metal.

• Good candidates: Aging metal roofs on homes, shops and outbuildings; modified bitumen, built-up, EPDM and some single-ply roofs (with compatible primers); existing sprayed foam roofs due for recoating; mobile home roofs.
• Usually poor candidates: Asphalt-shingle roofs (coatings can trap moisture and may conflict with shingle warranties), roofs with significant wet insulation, and roofs near the end of their life with widespread damage.

Before coating a low-slope roof, contractors often look for trapped moisture using infrared scans, moisture meters or core samples. Wet insulation should be cut out and replaced; coating over it seals the water in.

Types of roof coatings

Alaska-specific considerations

Ice dams are a heat-loss problem

Ice dams form when heat escaping from the house melts snow on the upper roof, and the meltwater refreezes at the colder eaves. A coating won't stop that cycle. The lasting fixes are air sealing the ceiling, adding attic insulation and providing ventilation where the roof design calls for it. Coatings may help with the leaks that result, but only after the root cause is addressed.

Snow load and sliding snow

Coatings add negligible strength. If a roof sags or has had snow-load issues, have it evaluated before spending on coatings. On metal roofs, a slick coating can change how snow sheds, so consider where sliding snow will land and whether snow guards are appropriate.

Short, sometimes damp application windows

Most coatings require a clean, dry, frost-free surface and minimum temperatures during application and early cure. Water-based acrylics in particular must not get rained on or freeze before they cure. In Southcentral and Southeast Alaska, that often means watching the forecast closely in mid-summer and avoiding late-day application when dew forms.

Wind and coastal exposure

Coastal communities see wind-driven rain and salt. Pay extra attention to seams, fasteners and flashing details, and for metal roofs, use rust-inhibitive primers where corrosion has started (see metal rust protection).

How a roof coating is applied

1. Inspection. Check deck condition, fasteners, seams, flashings and drainage; look for trapped moisture.
2. Repairs. Replace wet insulation and damaged areas; tighten or replace backed-out fasteners on metal roofs.
3. Cleaning. Power wash or clean to remove dirt, chalking and biological growth, then let the roof dry.
4. Priming. Apply primer where the manufacturer requires it, for example on rusted metal or certain membranes.
5. Detail work. Reinforce seams, fasteners, penetrations and flashing with fabric and mastic or a seam sealer.
6. Coating. Apply the specified thickness, typically in two coats, checking wet film thickness as you go. Thickness is what delivers the expected service life.

Permits, warranties and safety

Roof work may require a permit depending on the scope and your jurisdiction; check with the Municipality of Anchorage or your local building department. Manufacturer warranties usually depend on approved installers, specific thicknesses and inspection. Working on a roof is dangerous; use fall protection or hire a qualified contractor.