Moss in the Gutters

There is a version of moss work that stops at the roof edge, and it leaves the wettest part of the building untouched. This page is about the strip everyone skips: the trough itself, the hangers holding it, the fascia edge behind it, and the two or three roof courses immediately above.

It is deliberately narrow. Full gutter cleaning — debris, downspouts, flow checks, the whole run — is a trade of its own, and it is not this one. What is on this page is growth that has taken root, which is a different thing from a trough full of needles, and it comes off as part of a roof visit.

Why a trough grows things

A gutter is the wettest horizontal surface on a house. Everything that comes off the roof passes through it, and a good deal of that is grit — shingle granules, broken-down needle litter, dust that has washed down the slope. It settles in the bottom of the trough and, over a couple of wet seasons, turns into something with enough substance for a spore to root in.

After that it is a growing surface rather than a channel. Unlike a roof slope, which at least sheds and dries between showers, a trough with any fall problem at all holds water somewhere along its length from October right through to March. Growth in it does not have to survive a dry spell.

What follows is not a blockage in the usual sense. A blocked outlet is an event — water over the front edge in the next heavy rain. Growth is slower and quieter. It narrows the channel along its whole length, holds water rather than passing it, and puts weight into a run that was sized for a moving flow rather than a standing one. That weight is what starts hangers pulling away from the fascia, which is when a gutter problem turns into a fascia problem.

The fascia edge and the drip line

Behind and below the trough is a strip of fascia that stays damp in exactly the same way, and it is worth clearing while everything is open.

Lichen in particular likes it there. It shows up as flat grey-green patches on painted fascia and along the drip edge, and it keys into the paint film rather than sitting on top of it. Taken off early it comes away and leaves paint behind. Left for years it takes some paint with it, because by then the film underneath has already gone.

The lowest courses

The two or three roof courses immediately above a gutter are the part of a roof we look at hardest, and they are the part almost nobody can see.

They sit at the bottom of every drainage path on that slope, they are shaded by the gutter’s own edge, and on most houses they are directly under whatever is overhanging the eave. They stay wet longest of anything on the roof. On an asphalt roof this is usually where granule loss shows first; on cedar it is where the butts go soft.

Clearing the trough without clearing that strip means the growth is simply reseeded from six inches above, which is why the two get done together.

What we do not do

We do not clean gutters. We will lift out what has rooted, brush the trough, put water through it and tell you whether it went where it should — but a proper gutter service is debris clearing, downspout work, flow checking and knowing what a run should look like, and that deserves a crew who does it every day rather than an add-on from a moss crew.

If that is what you actually need, both of these are people we work alongside on this part of the Island:

• Saanich Gutter Cleaning — Saanich and the peninsula
• Totally Clean Gutters Victoria — Victoria and the core

Sending the work out is the honest answer, and it means neither job gets half-done.

Booked with the roof

This is almost never a visit on its own. The ladder is up, the roof is being cleared, and the trough and the roof edge are the last part of the same pass. Say so when you ask for an estimate and it is priced together.

Free estimate, Monday to Friday, insured and WCB-registered.

The slope above it is roof moss removal, and slowing the return is moss treatment and prevention.