The roof drains as designed
Clear slates, clear valleys and clear gutters mean rain leaves the building instead of sitting on it.
Roof Cleaning in ShetlandMoss, Lichen and GrowthRemoved Without Damage
Get a clean, free-draining roof that sheds island rain the way it was built to, without a jet wash stripping the surface off your slates or forcing water under them.
17 years' property experience · Lerwick-based team · Free, no-obligation estimate
17 years' experience
In Shetland property
Shetland & Orkney
Lerwick-based team
Mon–Fri, 9am–5pm
Local office hours
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Overview
What roof cleaning involves
Roof cleaning is the controlled removal of moss, lichen, algae and organic debris from the covering of your roof, slate, concrete tile, clay tile or profiled sheet, along with the valleys, verges and gutter line where that material collects.
On a Shetland roof the growth is rarely cosmetic only. Moss holds water directly against the covering, lifts slate tails, blocks the gaps that let a roof drain and breathe, and washes down into gutters and hoppers where it sits until something overflows. Cleaning the roof deals with the cause rather than the symptom further down the building.
We work to the covering in front of us. Natural slate, fibre cement and concrete tile all behave differently, and the method we use is chosen for the roof rather than for speed: scraping and brushing where that is right, low-pressure softwashing and biocide treatment where a mechanical approach would do harm.
Why professional work matters here
Roof work is height work. Access has to be set up properly, and on an exposed island site the weather window matters as much as the method.
A high-pressure wash aimed at a slate roof is the fastest way to strip the surface, loosen nibs and drive water under the covering. Undoing that costs far more than cleaning it correctly in the first place.
We come at this from managing property, not from a van that appeared last season. If the clean uncovers slipped slates, failed pointing or a tired flashing, we tell you about it and can carry out the repair with the same team.
Who it is for
- Homeowners with a visibly green or blackened roof that is getting worse each winter
- Landlords and property managers maintaining a portfolio across Shetland and Orkney
- Owners preparing a property for sale, survey or valuation
- Anyone whose gutters keep filling with grit and moss no matter how often they are cleared
When it is needed
- Moss visible on the tails of slates, in valleys or along the ridge
- Gutters repeatedly blocking with dark, gritty organic material
- Dark streaking or patchy green across a north-facing slope
- Before any roof coating, painting or exterior decoration work
- After a storm has left the roof carrying debris and displaced growth
What It Costs To Ignore
What happens if it is left
Left alone, moss does not stay still. The root system works into the joints and under the tails of slates, and each growth season it holds more water against a surface that was designed to shed it. In freeze-thaw weather that trapped water expands, and the damage moves from the growth itself to the covering underneath.
The second problem is drainage. Everything that falls off the roof ends up in the gutter. A roof carrying heavy growth will block gutters faster than you can clear them, and blocked gutters push water down the wall face, into the wallhead, and eventually into the fabric of the building. The repair bill for saturated masonry or a rotten wallplate is in a different category to the cost of cleaning a roof.
There is also the simple matter of what the property looks like. A blackened, mossy roof reads as a neglected building to a buyer, a surveyor or a prospective tenant, often before anyone has looked at anything else.
Common mistakes we are called out to
- Hiring a pressure washer and going up a ladder: the most common cause of avoidable slate damage we see
- Killing the moss and leaving it in place, so the dead material washes into the gutters over the following months
- Cleaning the roof and never clearing the gutters, guaranteeing an overflow at the first heavy rain
- Waiting until growth is inches thick, when slates have already been lifted and the work takes far longer
- Treating a roof in the wrong weather window, so the product is washed off before it has done anything
Our Process
How we carry out roof cleaning
Step 01
Inspection
We look at the covering, the pitch, the state of the valleys, flashings and ridge, and how the roof drains. You get an honest picture of what the roof needs, which is sometimes less than you expected, and occasionally more.
Step 02
Assessment and clear pricing
We tell you the method we would use and why, and give you a price for the work. No vague estimates and no pressure to decide on the doorstep.
Step 03
Safe access and protection
Access is set up for the property and the weather. Ground-level areas, planting, paths and drainage are protected before anything comes off the roof.
Step 04
Cleaning
Growth is removed using the method suited to the covering, careful mechanical removal, low-pressure softwashing, or biocide treatment where killing the growth at the root is the right call.
Step 05
Clearing the drainage line
Gutters, hoppers and outlets are cleared of everything the clean has brought down, so the roof and the drainage are dealt with as one job rather than two.
Step 06
Completion and walk-round
We tidy up, walk the job with you, and flag anything we found, slipped slates, failed pointing, a flashing on its way out, so you can decide what to do next.
Benefits
What you actually get out of it
Longer life from the covering you already have
Removing growth before it lifts slates is far cheaper than replacing sections of roof that failed early.
No surface damage
Method chosen for the covering, not for speed. Softwashing and controlled removal instead of a jet wash at full pressure.
Fewer blocked gutters
Most repeat gutter blockages on island properties start on the roof. Deal with the source and the clearing interval stretches out.
Problems found early
A clean puts trained eyes over every part of the roof. Small defects get reported while they are still small.
A property that presents properly
For sale, for letting, or simply for your own satisfaction, a clean roof changes how the whole building reads.
In Detail
Roof Cleaning, methods, materials and situations
Roof coverings we work on
- Natural slate, common on older Lerwick and Scalloway properties, and the covering most easily damaged by high pressure
- Fibre cement slate, durable but surface-sensitive; softwashing is almost always the right approach
- Concrete and clay tile, moss favours the textured surface of concrete tile in particular
- Profiled metal and cement sheet on outbuildings, workshops and agricultural buildings
- Flat and low-pitch roofs where standing water and organic debris are the main issue
Methods, and when we use each
Mechanical removal, brushing and scraping growth off by hand, is used where the covering is sound and the moss is thick enough that chemical treatment alone would leave a mat of dead material behind. It gives an immediate visible result.
Softwashing applies cleaning solution at low pressure, letting the product do the work instead of the water. It is the right method for fragile, painted, coated or surface-sensitive roofs and for any situation where forcing water uphill under a lap would be a risk.
Biocide treatment kills lichen and algae at the root so regrowth is slowed. It works over weeks rather than in an afternoon, and is often combined with removal for the best of both.
High-pressure washing has a narrow, specific place in roof work and is not our default. If someone offers to jet wash your slate roof, that is worth a second thought.
Why island roofs grow moss faster
Shetland and Orkney give moss everything it wants: persistent damp, mild winters by UK standards, clean air and long periods of low light on north-facing slopes. Add salt-laden wind carrying spores and grit inland, and a roof here will carry growth that an inland mainland property of the same age would not.
It also means the cleaning interval is shorter here. A roof cleaned properly and treated will stay clear for years, not decades, and planning for that is more useful than pretending otherwise.
Residential and commercial work
On houses the priorities are usually appearance, gutter performance and protecting the covering. Work is planned around the household, access is kept tidy, and the site is left clear at the end of each day.
On commercial and let property the priorities shift to access management, minimal disruption to occupants or trading, and a clear record of what was done. As a business that grew out of property management, scheduling around tenants and reporting back to an owner is routine for us rather than an inconvenience.
What we find while we are up there
- Slipped, cracked or delaminating slates
- Failed or missing ridge and verge pointing
- Lead and flashing detail that has lifted or split
- Gutter brackets pulling away from the fascia
- Blocked or damaged outlets and downpipes
- Vegetation growing in a valley or behind a chimney stack
BeforeAfter
Before & After
The same property, before and after
Drag the handle to compare. Both photographs are from one of our own roof cleaning jobs in Shetland.
Our Work
Roof Cleaning jobs we have carried out
Photographs from our own jobs on Shetland properties, no stock images.
Where We Work
Roof Cleaning across Shetland and Orkney
We are based on Commercial Street in Lerwick and travel across both island groups for cleaning and maintenance work.
Shetland
- Lerwick (base)
- Scalloway
- Brae
- Sandwick
- Whalsay
- Bressay
Orkney
- Kirkwall
- Stromness
- St Margaret's Hope
More detail on the areas we cover is on the homepage areas section.
Questions
Roof Cleaning: the things people ask first
How much does roof cleaning cost in Shetland?
It depends on the size and pitch of the roof, the covering, how much growth there is and how we can get access to it. We do not quote blind; we look at the roof and give you a clear price for the work before anything starts. The estimate is free and there is no obligation.
How long does a roof clean take?
Most domestic roofs are a one to two day job. A larger property, a difficult access situation or a roof carrying very heavy growth can run longer, and weather on the islands can move a date. We tell you the expected duration when we price the work.
Will cleaning damage my slates?
Not with the method matched to the covering, which is the whole point of how we work. Damage comes from high-pressure water aimed at surface-sensitive coverings. We softwash or remove growth mechanically where that is the right approach for your roof.
How long will the roof stay clean?
In this climate you should expect growth to return in time: damp, mild island conditions favour it. A biocide treatment slows regrowth considerably, and keeping gutters clear helps. We will give you a realistic view for your particular roof rather than a number that sounds good.
Do you clean the gutters as well?
Yes. Everything the clean brings off the roof ends up in the gutter line, so clearing gutters, hoppers and outlets is part of the job rather than an upsell.
Do you work in Orkney as well as Shetland?
Yes. We are based at 68 Commercial Street in Lerwick and work across the Shetland Islands and Orkney, including Scalloway, Brae, Sandwick, Whalsay, Kirkwall, Stromness and St Margaret's Hope.
What happens if you find a problem with the roof?
We tell you, with a straight explanation of how urgent it is. Because the same team carries out roofing and maintenance work, we can usually repair it rather than sending you looking for another trade.
Can you clean the roof in winter?
Some work can be done through the winter, but wind and driving rain limit safe access and affect how treatments perform. We plan the job around a sensible weather window rather than pushing on and doing it badly.
Do you offer emergency call-outs?
Our office hours are Monday to Friday, 9am to 5pm. Call 01595 747045 and tell us what has happened: if it is storm damage or water getting into the building we will tell you honestly how quickly we can be there.
Should I clean the roof before having it coated?
Always. A coating applied over moss, lichen or loose grime will not bond properly and will fail early. Cleaning is the first stage of any roof coating job we do.
Related Work
Other work the same team handles
Free Estimate
Get a clear price for cleaning your roof
Tell us the property type and what the roof looks like. We will come and assess it, explain the method we would use, and give you a firm price: free, with no obligation to go ahead.
property@arthurandsimpson.com
68 Commercial Street, Lerwick, Shetland ZE2 9EZ
Mon–Fri, 9am–5pm · Closed Sat & Sun
17 years' property experience · Lerwick-based team · Free, no-obligation estimates