Roof soft washing in Harvey Cedars

What owners tend to describe

• A neighbour's roof cleaned last year that still looks clean, next to yours that does not
• Moss or lichen sitting in the shingle courses on a shaded roof
• Dark patches on the north slope while the south slope still looks new

Why this comes up in Harvey Cedars

Here is what makes Harvey Cedars particular: the island is so narrow through the borough that a house can take ocean salt on one elevation and bayside damp on the other, and both are working on it at the same time. The bay-facing walls grow algae faster than almost anywhere on the island because the air off the meadow is humid and the afternoon shade is deep.

Heavily rebuilt after 2012, so a high proportion of the stock is modern, elevated and tall — three usable levels above a ground-floor entry is common. Cedar shake, painted fibre cement and PVC trim dominate, with a good deal of glass facing both water.

What access looks like here

There is very little room between houses here, and much of the bay side is reached through the property rather than around it. Boom and ladder work is the norm on the newer stock simply because of how tall it is.

Harvey Cedars handles permitting for work at this address.

What the work involves on this island

The black streaking is a cyanobacteria, Gloeocapsa magma, that feeds on limestone filler in asphalt shingles. The Asphalt Roofing Manufacturers Association's guidance is low pressure and a cleaning solution; pressure washing strips granules and is excluded under most shingle warranties. Ask what pressure the crew works at and what they do to protect the gutters, plantings and the run-off path before they start.