Roof Moss Removal and Cleaning in Manchester

How moss gets a hold, and what it does next

It starts where the roof stays wet longest: the north facing pitch, the shaded side, anything under a tree. Concrete tile is worst for it, because the surface goes porous and holds moisture instead of shedding it. Once established, a clump holds water against the covering all winter, and it is water held in a joint and then frozen that does the damage rather than the moss. Then it comes off. Rain and frost break the clumps free and gravity takes them into the valley, or over the eaves into the gutter and along to the outlet. That is where something cosmetic turns into a wet wall, and it is why we go at the valleys and the outlets before we worry about how the tiles look.

How to read your own roof

Most of this you can do from the pavement. An even green film across the tiles is algae and it is doing nothing. Thick clumps standing proud in the pans, along the shaded side and up near the ridge, are worth clearing. Look at the valley between two pitches: a clean channel, or a trough packed with the stuff. Look in the gutter after a dry spell, because a black seam along the bottom is moss silt heading for the outlet. What we would ask you not to do is climb up for a closer look.

What happens if it is left

Nothing dramatic happens to the tiles for a long time. The damage arrives through the blockages. A silted valley cannot take the water off two pitches at once, so in a downpour it backs up over the tiles either side and runs into the roof where the boarding is already weakest. A blocked outlet holds water until it comes over the edge onto the wall, which goes green under the fault while the plaster inside blows near the ceiling. On an old slate roof there is one more: moss dams water at the head lap and pushes it sideways under the course, which puts water inside the roof with nothing visibly wrong outside.

Roof coatings, honestly

Worth reading properly, because roof coatings are the classic doorstep sell around here and the pitch is persuasive. Here is what is true. First, a coating painted onto your tiles does not insulate your house. Insulation works by putting thickness between the warm side and the cold side, which is why it goes in the loft. A film of paint on a tile cannot do that at any thickness anybody sprays. Second, a coating does not repair what is underneath it: if the nails have rusted through the tiles are still going to slip, and if the ridge mortar has cracked it is still cracked under the paint. Third, sealing the top face of a porous covering leaves moisture in the tile with nowhere to go, and on natural slate it can do worse than nothing. Fourth, a coated roof is harder for the next roofer to work on, because coated tiles cannot be matched or reused. We do not sell roof coatings. We do not apply them and we will not quote for one. If somebody has knocked, the pattern is the same. They are working on a roof nearby, they have spotted something from the road, and there is a figure that only holds today. Do not agree to anything at your own front door. A contract agreed at home carries cancellation rights worth reading up on at Citizens Advice first, and any honest roofer will still be there next week.

Moss on Manchester roofs, and why there is so much of it

Damp air, mill towns sitting in river valleys, and a great deal of tree cover. The streets running down toward the Irwell and along the canal lines hold moisture in a way open ground a mile away does not, and those roofs fill their gutters quicker. The estates built through the fifties, sixties and seventies carry concrete interlocking tile now chalky and porous, which is exactly the surface moss wants. The Victorian terraces are Welsh slate, smoother and steeper, so they shed it better, but everything off two paired roofs lands in the shared lead valley between them. Out toward Bury and Ramsbottom there are stone flag roofs, heavy and fragile at once, and those get cleared very gently or not at all.

How we clear it

By hand. A scraper and a brush, working down the pitch so nothing is driven up under the laps, and the debris caught rather than left to find the gutters. Valleys, gutter runs and outlets are cleared in the same visit, because that is where all of it has gone. While we are up there we look at what the moss was hiding, and slipped tiles, cracked bedding or a failed flashing under it are priced separately in a free written quote, so you can see which part is cleaning and which part is repair. We do not jet wash roofs. High pressure strips the surface off an old concrete tile and takes years off its life, and on slate it drives water straight under the courses. Treatments that slow regrowth exist, but none of them replaces clearing a valley.

Is it worth doing, and what affects the price

Sometimes the honest answer is that it is not worth doing yet, and if that is what we think we will say so on the day rather than take the work. Where it is worth doing, the figure follows how much of the pitch is genuinely mossed rather than how big the house is, then whether the covering is sound enough to be worked off or fragile enough to need roof ladders and boards. After that it is how much has to be bagged and carried away, and where it lands, because clearing over a conservatory, a greenhouse or next door's drive has to be caught rather than swept. Access is the other one, as it is everywhere. Gutters and valleys done at the same time go in the same free written quote.

Frequently Asked Questions

Does moss actually damage my roof?

Less than you have probably been told. On a sound concrete tile roof a light growth does almost nothing, and we will say so. It matters when it is thick enough to hold water through a frost, when it sits in a valley, or when it is filling the outlets. The rest is how the roof looks, which is a fair reason to want it done, but it is not a repair.

Will pressure washing damage my roof?

It can, and on the wrong covering it certainly will, which is why we clear by hand and look at what the roof is made of first.

Somebody knocked and said my roof needs coating urgently. Should I worry?

Get a second opinion before you agree to anything on the doorstep. A coating is not a repair and it will not insulate the house, and a roof that has waited this long will wait another week.

Will the moss come back?

Yes. Any shaded pitch in Greater Manchester grows moss again, and how fast depends on the trees, the aspect and how porous the covering has become. Anybody promising you a roof that stays clear for good is selling you something.

Will you clear the gutters at the same time?

Yes, and we would push you to. Clearing the roof and leaving the gutters just moves the problem down a level, so both go in one free written quote.