Roof cleaning

You notice it from the garden in autumn: the north side of the roof has turned green. Not everywhere — but in the areas under the trees, along the ridge and in the valleys, the moss lies thick enough to see from the ground. And each autumn it is a little larger than the year before.

It looks like a cosmetic problem. It is a moisture problem, and moisture problems on a roof are expensive.

What we actually do

We use the softwash method: low pressure, the right chemistry and dwell time. It is a slower method than high pressure, and that is the whole point.

1. Inspection first. Roof type, age, pitch, access and condition. We look for cracked and loose roof tiles, the condition of the valleys and penetrations, and how much moss is actually there. The fixed price is set after this, not before.
2. Protection and covering. The work area is secured, and plants, beds and facade are covered.
3. Thick moss is removed mechanically before any chemistry is applied, carefully and working upward, so that we do not pull tiles out of position.
4. Algae-killing agent is applied at low pressure and given time to work. Algae and moss are living organisms rooted in the pores — they must be killed, not just rinsed off. An agent with dwell time is why the roof stays clean for a year, not just for weeks.
5. All surfaces are treated. Roof surfaces, hips, ridge edge and valleys. Around chimneys, roof windows, vents and penetrations, which are where leaks actually begin.
6. Gutters and downpipes are cleaned, and we check that water flows freely all the way down. A roof clean that leaves the gutters full of moss has created a new problem.
7. Inspection and documentation. Loose or cracked roof tiles are noted and reported to you. Moss and debris are removed. You receive before and after photos.

Why it pays off

Moss is a sponge. It holds water against the roof tile around the clock, long after the rain has stopped. In winter that water freezes, expands, and breaks small pieces off the surface of the tile. It does not happen in one winter — it happens over twenty, and the result is roof tiles that absorb water instead of shedding it.

Then there are the gutters. Moss that comes loose naturally ends up in the gutters, blocks the downpipes, and then the water runs over the edge and down the facade and foundation instead of into the drain. That is the mechanism behind rot damage in cladding and moisture in basements.

The arithmetic is then fairly simple. A roof clean at approx. kr 9 000 every four or five years is maintenance. A new roof is an investment on an entirely different scale — and a roof that is kept clean reaches the age the manufacturer stated.

And when selling: a green roof is something every buyer in Vestfold knows to factor into their offer.

How often should you have it done?

Every 3 to 5 years for most roofs. If the house sits under trees or on the shaded side of a slope, aim for the shorter end. If the roof has just been cleaned, it is enough to check it each autumn — if green appears on the north side again, it is time.

How long does it take?

A full working day, around 8 hours, for a typical detached-house roof. We need dry weather, both for the dwell time and for safety.

Book a roof cleaning inspection — you receive a fixed price in writing after the inspection, and we do not begin until you have approved it.