Stain or paint for cedar shingles on Massachusetts houses

What actually happens to cedar shingles in salt air and morning dew?

Western red cedar and white cedar shingles are soft, porous and full of natural oils and tannins. On a cottage in Houghs Neck, Squantum or Adams Shore they spend months wet from dew, fog and wind-driven rain off the bay, then bake in summer sun. Bare cedar turns silver gray within a season or two on the south and west walls and darker, sometimes blotchy, on the shaded north side where mildew settles in. That uneven aging is the reason most owners start asking about stain.

The shingles also move. Each one swells when wet and shrinks when dry, and a wall of shingles has thousands of exposed edges and butts that drink water. Any coating you choose has to cope with that movement and let trapped moisture leave. That single fact decides most of the stain versus paint question, and it is why a finish that works on clapboard often fails on shingles.

How do semi-transparent, solid stain, bleaching oil and paint compare?

The four common finishes sit on a scale from soaking into the wood to forming a film on top of it. The more a product soaks in, the less it can peel, and the more of the cedar grain you see. The more it builds a film, the more color and hiding you get, and the more care the prep needs. Here is how they line up on a typical shingled bungalow on the Quincy peninsulas or a Shingle Style house in Milton or Wellesley.

None of these is wrong. The right pick depends on what is on the wall now, how much grain you want to see, and how often you are willing to recoat. A wall that already carries paint or solid stain cannot go back to a semi-transparent look without stripping or replacing shingles.

• Bleaching oil: a penetrating oil with a graying agent that speeds an even driftwood color; reapply every 2 to 4 years or let it weather.
• Semi-transparent oil stain: tints the wood, shows grain, never peels, fades evenly; recoat every 3 to 5 years.
• Solid acrylic stain: hides grain and old color like a thin paint, breathes better than paint; recoat every 5 to 8 years.
• Exterior acrylic paint: thickest film and crispest color, but most likely to blister and peel on shingles that get wet from behind.

Why does paint so often peel on shingle siding?

Shingles are laid in overlapping courses, so water that gets behind one shingle has plenty of places to sit. Many of the converted summer cottages around Quincy Bay were built with little or no housewrap, and once they were winterized, moisture from bathrooms, kitchens and basements began migrating outward every heating season. A thick paint film slows that vapor down. It collects under the paint at the butt edges and in the keyways, then lifts the coating in curls and blisters, usually on the lower courses and under windows first.

Paint can still work on shingles that were painted long ago and have held up, especially on walls under deep eaves. In that case we keep the system the house already has, scrape and sand loose edges, spot prime bare cedar with a stain-blocking primer, and topcoat with a quality acrylic. What we avoid is putting new paint on bare or stained shingles that never needed a film in the first place.

How should cedar shingles be prepped before any stain goes on?

Prep is where shingle jobs succeed or fail. Gray, weathered cedar has a loose layer of broken fibers on the surface, and stain applied over it sits on that layer instead of in sound wood. We clean shingles with a wood cleaner or a mild oxygen bleach solution, scrub mildew on the north walls, and rinse at low pressure to carry off salt film as well. High pressure tears the soft cedar and raises fuzz, so the wand stays well back from the wall.

After cleaning, the wall needs to dry. On a dewy morning near Wollaston Beach that can mean waiting until midday, and after a rain we usually give shingles at least two dry days before staining. Loose or split shingles get replaced and nailed with stainless or hot-dipped galvanized nails, since plain steel nails bleed rust streaks through light stain, and faster in salt air. Trim is protected, plants are covered, and windows are masked.

• Clean and treat mildew, then rinse gently
• Let the cedar dry until a moisture meter reads in the low to mid teens
• Replace cupped, split or rotted shingles
• Back-brush every course so stain reaches the butts and keyways

How often will you really need to recoat, and what speeds it up?

Recoat cycles are ranges, not promises, because exposure matters more than the label. A south-facing wall on Houghs Neck that takes the full sun and the wind off the water weathers far faster than a north wall shaded by oaks in West Quincy or Canton. On the same house, the sunny sides of a semi-transparent job may want attention in year three while the shaded side looks fine at year five. Many owners recoat the hard sides first and the whole house every second cycle.

The best sign it is time is how the wood takes water. Splash a little on the sunniest wall: if it beads, the finish is still working; if it darkens and soaks in within a minute, the cedar is open and ready. With semi-transparent stain, recoating at that point is a simple clean and one coat. Wait too long and the wall goes gray again and needs fuller prep. Solid stain shows its age through chalking and faded color on the sun sides.

What does staining a cedar shingle house cost in the Quincy area?

For planning, a full semi-transparent or solid stain job on a typical shingled cottage, cape or two-story Colonial around Quincy often lands somewhere in the range of $5,280 to $12,650, with larger Shingle Style houses and steep, tall walls going higher. Recoats on a house that has been kept up sit toward the low end, because prep is lighter. These are typical ranges only. The walk-through sets the real number once we see the wall height, condition and existing finish.

The biggest swings come from what is on the wall now. Bare cedar that only needs cleaning is the simplest case. Peeling paint on shingles is the hardest, because it has to be scraped back or the worst courses replaced before a stain will look right. Shingle replacement, mildew treatment on shaded walls, ladder or lift access on a tight peninsula lot and trim painting all move the figure. Call (617) 576-8235 any hour to set up a walk-through and a written estimate.