Is Pressure Washing a Roof Safe?A pressure washer makes a roof look clean in minutes, and that speed is the problem. This guide explains what a hard…Guide · 9 min readRoof Cleaning & Moss Removal in Crawley
Moss off by hand, tiles checked by roofers, gutters cleared.
Our roof cleaning in Crawley and across Sussex and Surrey removes moss, lichen and algae by hand and with gentle washing, treats the surface, clears the gutters and checks the tiles, with one written price.
- Survey photos of your own roof
- One written price
- Repairs, re-roofs and emergencies
- Tidy site, waste taken away
Signs your roof is ready for a clean
- Green cushions along the ridge and tile edges
- Dark streaks running down a shaded slope
- Grey or orange crusts stuck to the tiles
- Moss and leaves piling up in the gutters
- A surveyor or buyer has mentioned the roof
What a roof clean from us covers
Hand moss removalMoss lifted off the tiles with scrapers and soft brushes, working down the slope so nothing is pushed under the laps.
Gentle soft washingLichen and algae washed from the tile face at low pressure, so the surface of the tile stays intact.
Biocide treatmentAn authorised biocide applied to the cleaned roof, following the product label, to slow the return of growth.
Gutter clearingMoss, silt and leaves cleared from gutters and outlets, with the run checked for sagging joints afterwards.
Roof condition checkSlipped, cracked or loose tiles, ridges and flashings noted and photographed as the roof comes clean.
Repairs while we are thereAny fault we find priced in writing before work starts, then fixed on the same job if you agree.
Clean it, repair it first, or re-roof?
- CleanThe tiles are sound and the growth sits on top: lift it off and treat it.
- Repair firstTiles are cracked, loose or crumbling: fix those before any washing begins.
- Re-roofTiles and battens are worn across the slope: a clean would only delay the larger job.
How a roof clean runs from call to finish
- 1Photo of the worst slopeSend a picture from the ground and tell us the house type and where the moss is heaviest.
- 2A survey of the roofWe check access, tile condition, gutters and any fragile roofs, photographing each point as we go.
- 3One written priceYou get one total for the clean, with the photos and the method we propose for your tiles.
- 4Clean, treat, clear, checkWe remove the growth, apply the treatment, clear the gutters and send you after photos.
The roof cleaning diary
Inside a roof clean and moss removal job
Six stages of a roof clean around Crawley, from telling moss from lichen on the ground to the last look along the gutters.
Stage 01 · First look
Roof cleaning in Crawley, done by roofers
A roof clean is a roofing job as much as a cleaning one, so the person on the slope should read tiles properly.
Roof cleaning, Crawley or anywhere else, starts with knowing what is growing on the roof. Moss is the thick green cushion that collects along ridges, in the gaps between tiles and wherever the surface stays damp. Lichen is the flat, crusty patch in grey, orange or pale green that sits tight against the tile. Algae shows as dark streaks, most often down a slope that gets little sun. Each one holds moisture against the covering, and each calls for a slightly different approach, so we identify what is there before deciding how to treat it. We come to the work as roofers, which matters because the person standing on the slope sees every tile as it comes clean and can tell a sound one from a tired one.
- Moss along the ridge
- Lichen crust on a tile
- Dark algae streaking
- Moss at the tile edge
What does a mossy roof do to the tiles underneath?
Moss holds water against the tile and keeps it there long after the rain has stopped. A thick mat can also sit across the joint between two tiles and steer water sideways, and in the gutter it can choke an outlet until rain spills over the fascia board. None of that means a mossy roof is about to fail. A light covering on a sound roof is mainly a question of looks, and we tell you that when it is what we find. The trouble starts when growth sits on tiles that are already worn, because a damp surface weathers faster and the mat hides cracks you cannot see from the ground. That is why we look at the tiles as well as the moss. Our blog post asking whether moss is damaging your roof compares the removal methods side by side, and the pages below go through each one in turn.
Why does one roof go green faster than its neighbour?
Shade, shelter and slope decide it. A north-facing slope dries slowly, overhanging branches drop leaves and keep the surface damp, and a low pitch lets water linger. Crawley was laid out neighbourhood by neighbourhood, so on a street built in one go the roofs often share the same tile, and the difference you see between neighbours usually comes from the trees and the aspect rather than the covering. The answer we give is never a guess from the road. Whichever tile you have, the sequence is the same: we read the roof, choose the gentlest method that will work, clean it, treat it and look again at what the clean has revealed. If you are choosing between roof cleaners, Crawley firms included, ask each of them who will actually be on the roof and what they will do if they find a loose tile.
Keep reading
Is it worth cleaning a roof that still looks fine from the street?
Sometimes it is, and sometimes it is not. A roof with a thin film of algae and sound tiles can wait, and we will say so rather than book you in. A roof with moss packed along the ridge and into the valleys, or with gutters that overflow every time it rains, is different, because the damp is already doing something. Looking from a bedroom window or the garden tells you more than a glance from the pavement, and a photo from the ground is all we need to give you a first opinion.
Stage 02 · Method
Roof moss removal in Crawley: our method
We remove moss by hand first, then wash the tiles gently, because the aim is a clean roof with the surface still intact.
Roof moss removal, Crawley or anywhere else, is slow, careful work, and the order matters. We start at the ridge and work downwards, so that loosened moss never gets pushed up under a tile above it, and we lay boards or ladders where we need to spread our weight. Before any tool touches the roof we look at the tiles themselves. A tile with a flaking face or a snapped nib is marked for repair rather than scrubbed, because cleaning a failing tile only finishes it off.
How is moss taken off a roof by hand?
Thick moss comes off with a flat scraper and a stiff but soft-bristled brush, a section at a time, and drops into the gutter or is lifted straight into a bag. We keep the tools flat to the tile and move with the lay of the covering, never against the laps. Our guide to manual moss removal and scraping by hand describes the tools and the technique in more detail. Hand work is slower than a jet, and it is gentler on the tile. It also means we notice every cracked or loose tile as we reach it, which is how most of the faults we report are found.
What we check before cleaning
- Tile face
- Sound surface, no flaking or crumbling
- Fixings
- Tiles seated, nibs and clips holding
- Access
- Ladder, tower or scaffold, set safely
- Fragile areas
- Sheet roofs and rooflights identified first
What is soft washing, and when do we use it?
Once the thick growth is off, the thin film of lichen and algae that remains is washed from the tile face at low pressure, with water carrying the cleaning solution rather than force doing the work. The tile surface is not blasted, and the water is directed down the slope rather than up under the laps. We keep the pressure low and the nozzle at a distance, and we stop if the tile surface starts to come away. On some roofs the hand work alone is enough, and the washing is left out.
Why do we keep high-pressure jets off the tiles?
Marley, a major tile maker, says that "the use of high powered jet washes is not recommended as it can damage the surface of the slate or tile, thus reducing its expected life considerably." A jet can also drive water up under the laps and into the loft. For that reason we keep to low-pressure washing, and our guide on whether pressure washing a roof is safe sets out the reasoning. On slate or thin clay tile we lean even more on the hand work, and the wash is kept light. Concrete tiles carry a surface layer, and heavy jetting can strip it, which leaves a rougher face that holds the next lot of growth.
Keep reading
Safety on the roof comes into every step. We set the access before the first tile is touched: a ladder with a roof ladder for a low slope, a tower for a taller house, or a scaffold where the height or the pitch calls for it. Wet moss is slippery, and a roof that is being washed is slipperier still, so we work in dry conditions where we can and we never stand on a slope we have not checked. Neighbours' gardens, parked cars and your own windows are covered or moved clear before any water is used, and you are told what is happening each day.
Stage 03 · Treatment
Roof biocide treatment after the clean
Cleaning removes what is there. A biocide treatment slows what grows back, and it has to be applied properly, to the label.
A roof biocide treatment is a product sprayed onto the cleaned tiles to kill the spores and root fragments of moss, lichen and algae that the brush and the wash leave behind. Without it, growth tends to return from what was missed, so for the roofs we clean it is a sensible final step. It is also the stage where the rules matter most, because the products are regulated. Our page on how biocide roof treatment works goes through what happens on the roof after the product is applied.
Treatment words
- Biocide
- Product that kills moss, lichen and algae
- Soft wash
- Low-pressure wash carrying a cleaning solution
- Lichen
- Crusty growth that grips the tile
- Data sheet
- Maker's page of use and limits
Who is allowed to use these products?
The HSE is clear that the public should never use any biocidal product made only for professionals, and it adds that professionals themselves need specific certification for some of those products. The law also requires biocidal products to be used in line with the terms of their authorisation and their label. In practice that means we choose a product authorised for the job, read the label, follow the dilution and the dry-time it gives, and keep it away from places it should not reach. Nobody may advertise a product as approved by the HSE, so you will not see us do it.
What about the garden, the pond and the pets?
Run-off from a treated roof ends up in the gutter and the downpipe, and from there in a drain or a water butt. Before we start we ask where your downpipes run, move planters and covers where we can, and disconnect or cover a water butt for the day. Our guide to roof cleaning chemicals, gardens and ponds goes into the precautions in full. The label sets the time before people and animals can go back to the area, and we tell you what it says for the product we use.
Should the roof be coated after cleaning?
A coating is a separate decision from a clean, and it is not always needed. A coating changes how the tile looks and behaves, so it is worth reading the maker's data sheet and asking what it says about the tile you have. Our guide to roof tile coatings and whether they are worth it covers the questions to ask. If we think a coating adds nothing for your roof, we will tell you that plainly, and the written price will not include one.
A clean roof looks right on the day. The treatment decides how it looks next winter.
If someone in the house is sensitive to sprays, or you keep animals that roam freely, tell us at the survey. We can choose the timing of the treatment, ask you to keep windows closed for the day and agree where pets and children stay until the label says the area is safe to use again.
Ask how long a treatment is expected to last and you will get a range of answers, because shade, trees, the slope and the tile surface all play a part. The position is that the product's label and data sheet give the maker's claim, and your own roof then decides. We put that claim in front of you with the written price, and we say plainly if your roof is the sort that grows moss back sooner, such as a shaded slope under branches.
Stage 04 · Clear-out
Gutter cleaning in Crawley with every roof clean
Moss does not stay on the roof. It ends up in the gutter, so clearing the gutters finishes a roof clean properly.
Gutter cleaning, Crawley or anywhere else, belongs in the same visit as the roof clean, because every handful of moss we lift from the tiles has to go somewhere. Some of it we bag from the slope. The rest of what loosens, including grit from the tile faces, drops to the eaves and into the gutter, where it joins whatever was already there. If we left the gutters as they were, the next rain would carry that debris into the outlets. So we clear the gutter run by hand, outlet by outlet, from a ladder or tower set up for the job, and flush the downpipes to prove the water has a clear way out.
What do we look for in the gutter itself?
A clear gutter shows its faults. We watch for joints that weep, brackets that have pulled away, a run that sags between fixings and standing water that suggests the fall has gone. Our guide on moss in gutters and clearing up after a roof clean explains why gutters collect it. If the gutter is failing, a clean will not cure it, and we show you the photos. Renewing the guttering, soffits and fascias is a different job covered on our gutters, soffits and fascias page.
What to look at
- Gutter run at the eaves
- Downpipe outlet
- Fascia board behind
- Eaves tile course
What about concrete gutters and flat roofs?
Some 1950s houses were built with concrete gutters of the Finlock type, and an RICS defects record on them notes that leaking joints have badly damaged many examples, while warning that removal should not be taken for granted. On a gutter like that we lift debris out gently and avoid scraping across the joints. Flat-roofed garage blocks and extensions collect moss and leaves in the same way, and their outlets can block quickly, so we clear those as well. Our flat roofing page covers what differs when the surface is membrane rather than tile, and we use softer tools on felt, EPDM and GRP alike.
What if there is a nest or a roost in the roofline?
Birds and bats use gutters, soffits and roof edges. Wild birds are protected by the Wildlife and Countryside Act 1981, under which deliberately removing a nest, or harming one that is occupied or still being built, is an offence, and GOV.UK names repairing a roof as one activity capable of affecting bats, whose roosts have full legal protection. If we find a nest in use or any sign of bats, we stop that section and talk to you before doing anything more. A short delay is a small price for keeping the work on the right side of the law, and we agree a new date with you.
Keep reading
Once the runs are clear we run water through them and watch it travel. Water that stands in a section tells us the fall has gone, and water that leaks at a joint or behind a bracket is something you will want to know about before the autumn. You get photos of anything we flag, and you can decide whether to book guttering work with us or with someone else.
Stage 05 · Condition
Roof health check and repairs on one visit
A clean roof shows you what was hidden under the moss. Because we are roofers, we can deal with whatever we find.
Most roof cleaners clean and leave. We are roofers, so the health check is part of the job. As each section comes clean we look at it properly: the tile faces, the ridge, the hips, the verges, the flashings around chimneys and walls, and the eaves. We photograph anything that is not right and mark it, and when the roof is finished you get a short report with the photos. It is a survey, taken on the way through, and it is the same kind of look we give any roof before we price a repair.
Which services follow if we find a cracked tile?
Small faults are common once the cover of moss is gone. A single tile can be replaced on the spot if you agree, using the method on our page about pitched roofing, and a cracked tile found mid-clean is photographed before and after, so you see exactly what was done. Anything bigger is explained first, with the photos, and quoted as one written total before work begins. Nothing is added on the day without your agreement.
What the health check covers
- Tiles
- Cracked, slipped or crumbling ones marked
- Ridge and hips
- Caps tight, joints sound, fixings present
- Flashings
- Sealed to walls and stacks
- Gutters
- Joints, falls and brackets checked
- Loft side
- Daylight or damp marks reported
Is the ridge safe to clean around?
A mortar-bedded ridge that is cracked can rock under a brush, so we test it by eye and by touch before we put weight near it. Since the 2014 revision of BS 5534, Marley points out, mortar by itself is not trusted to hold down the ridge and the hips, and any bedded fitting should also carry mechanical fixings. If a ridge turns out to be loose, a repair with mechanical fixings is usually the next step, and we will tell you if a dry system would suit the roof better.
You receive the photographs by email or WhatsApp, in the order we took them, with a line under each saying what we saw. Faults that need action are listed first, and anything we would simply keep an eye on is listed after them. Nothing is dressed up to sound worse than it is, because a roof that needs nothing more than a clean should be told so, and a roof that needs a repair should hear that from the photographs rather than from a sales pitch.
Moss can hide a cracked tile. A clean roof gives it nowhere to hide.
What about garage and outbuilding roofs?
Corrugated sheets on a garage, shed or older extension need to be identified before anyone walks on them. HSE guidance warns that these roofs are always fragile, and it advises assuming asbestos is present in any building put up or refurbished before 2000. If we meet a sheet roof we are not sure of, we do not step onto it, we tell you, and we look at it from the ground or a ladder first.
You can use the health check for more than the repair itself. A buyer's survey, a mortgage valuation or a landlord's inspection may well have flagged the roof, and a dated set of photographs after the clean shows the condition of the tiles at that point. Cleaning before you list can make sense when the roof is the first thing a buyer sees from the pavement. The photographs also give you a record to hold on to, so that next time you can compare the roof with how it looked after this clean.
- £8.50 to £14per m² for roof cleaning, April 2026
- Around £11.50per m², hand removal plus biocide
- Around £18per m² for scaffold, if needed
Stage 06 · Pricing
Roof cleaning cost in Crawley
The price of a roof clean turns on four things: the size of the roof, the access, the method and the roof beneath.
Roof cleaning cost, Crawley or elsewhere, depends on the roof, so the written quote gives a single total once we have surveyed and photographed the roof. We do not publish a roof cleaning price list, because two roofs that look alike from the road can differ by a good deal once you are on them. The size of the roof, the height and access, the method the tiles can stand and the state of the gutters decide the figure, and you are always told what it covers before you agree.
What do national guides say roof cleaning costs?
Checkatrade's roof cleaning cost guide, with a table dated April 2026, gives a typical UK range of £8.50 to £14 per m², and around £11.50 per m² for hand removal plus biocide. The same guide puts a semi-detached house at £637.50 to £862.50. These come from a national guide and say nothing about our own pricing, and every roof differs, but they let you spot a quote for roof cleaning in Crawley a long way above or below the range. Our answer on how much roof cleaning costs goes through the figures.
Why does access change the price of a clean?
A bungalow roof can often be worked from a ladder and a roof ladder. A two-storey house with a steep rear slope may need a tower or a scaffold, and the guide gives scaffold at around £18 per m² on top. Scaffold on the public pavement or road needs the licence that section 169 of the Highways Act 1980 requires from the highway authority. We sort that out together with the scaffolder before anything goes up. Scaffold on private land needs none. A licence takes time to come through, so a roof that needs scaffold is booked later than one that needs a ladder.
What should a roof cleaning quote tell you?
It should be a total in writing, and it should say which slopes and outbuildings it covers, what method will be used, whether the gutters are included, and whether VAT and any scaffolding are in the figure. Check each of those if you are weighing up more than one quote. A price that looks low may leave out the gutters or the treatment.
Pricing words
- Aspect
- The direction a slope faces
- Access
- How we reach and work on the roof
- Scaffold licence
- Permission for scaffold on public highway
- Off-premises contract
- A contract signed away from our premises
If you sign for the work at home after our visit, the contract is an off-premises contract, and you normally have 14 days from the day you sign to cancel. The right to cancel is lost if you called us out specially for urgent repairs, though a roof clean is rarely that, and you should never feel rushed into signing. For a first price, send a photo of the worst slope taken from the ground, name the house type and say whether the gutters overflow, so we know where to look on arrival.
Typical UK prices for roof cleaning
| Work | Guide price |
|---|---|
| Roof cleaning, all methods | £8.50 to £14 per m² |
| Clean for a semi-detached house | £637.50 to £862.50 |
| Gutter clearing with the clean | priced on survey |
These are guide figures from a national source, so treat them as context. Your own figure arrives as a single total in writing once we have looked at the roof.
Checkatrade roof cleaning cost guide, table dated April 2026 (hand removal plus biocide averages around £11.50 per m²; scaffold around £18 per m²).
Roof cleaning guides and answers
Quick answers and longer reads on moss, biocide, soft washing, coatings and gutters, for anyone deciding how their roof should be cleaned.
Guides and posts
Is Pressure Washing a Roof Safe?A pressure washer makes a roof look clean in minutes, and that speed is the problem. This guide explains what a hard…Guide · 9 min read
How Biocide Roof Treatment WorksSpraying a biocide onto a mossy roof sounds simple, yet the products are regulated and the results arrive slowly.…Guide · 9 min read
Roof Tile Coatings: Worth It or Not?Coatings are sold after a roof clean as a way to lock in the result. This guide asks what they can do, what they…Guide · 9 min read
Cleaning Your Roof Before Selling Your HouseA mossy roof catches a buyer's eye from the pavement and gives a surveyor an easy line to write. This guide covers…Guide · 9 min read
Cleaning a Clay Tile or Historic RoofClay, slate and historic roofs are cleaned differently from modern concrete ones. This guide explains the gentle…Guide · 9 min read
Manual Moss Removal: Scraping by HandScraping moss off by hand is the slowest way to clean a roof and the kindest to the tiles. This guide shows how it is…Guide · 9 min read
Roof Soft Washing ExplainedSoft washing swaps force for a treatment solution applied at low pressure. This guide explains the method, how…Guide · 9 min read
Moss in Gutters: Clearing Up After a Roof CleanMoss rarely stays where it grows. It slides, flakes and washes into the gutter below, and a roof clean that ignores…Guide · 9 min read
Cleaning Moss Off a Flat RoofMoss on a flat roof is a symptom, usually of water that has nowhere to go. This guide covers safe clearing on felt…Guide · 9 min read
Roof Cleaning Chemicals, Gardens and PondsWhatever is sprayed on a roof ends up at ground level. This guide follows the water from tile to gutter to garden…Guide · 9 min read
Should You Clean Your Roof? Advice on Roof CleaningNot every roof needs cleaning, and not every dirty one is a problem. Here is how to decide, from what the roof is…Blog · 9 min read
Is Moss Damaging Your Roof? Moss Removal Methods ComparedA green roof looks harmless, but moss holds water against tiles and can choke gutters. Here is what it does, and how…Blog · 9 min readQuick answers
- How Much Does Roof Cleaning Cost?
- How Long Does a Roof Biocide Treatment Last?
- How Often Should You Clean Your Roof?
- Should You Coat Your Roof After Cleaning?
- Can Moss Cause a Roof Leak?
- Is Lichen on Roof Tiles a Problem?
- Can a Roof Be Cleaned in Winter?
- Can You Remove Moss From Your Roof Yourself?
- What Are the Black Streaks on My Roof?
- Why Does Moss Grow on the North Side of a Roof?
- Do Zinc Strips Stop Roof Moss?
- Why Do Concrete Roof Tiles Get So Mossy?
- Is Roof Biocide Safe for Pets and Children?
- Does Home Insurance Cover Moss Damage?
- How Do You Get Rid of Green Algae on a Roof?
- How Do You Clean a Conservatory Roof?
- Should Solar Panels Be Cleaned With the Roof?
- How Long Does a Roof Clean Take?
- What If Broken Tiles Are Found During a Roof Clean?
- What Is the Best Moss Killer for a Roof?
Related services
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Flat roofingOur flat roofing service covers garage, extension, dormer and balcony roofs in Crawley and the towns around it: GRP…
Dry ridge & dry vergeOur dry ridge work in Crawley covers loose ridge tiles, failing verge mortar, rattling verge caps and full dry-fix…Roof cleaning questions
Will cleaning the roof stop a leak I already have?
Not by itself. A clean removes growth and lets us see the tiles, but a leak comes from a fault such as a slipped tile, a failed flashing or a cracked valley. Moss can hide those, so the clean often helps us find the cause. We then explain what we found, with photos, and give a written price for putting it right.
Which roof tiles are safe to clean by hand?
Most sound concrete, clay and slate roofs can be cleaned by hand with soft tools, provided the tiles are well seated. A tile with a flaking face or a snapped nib is marked for repair instead. Old handmade peg tiles need extra care, and Marley's jet-wash warning applies with extra force to any tile whose surface is already worn.
Who should apply a roof biocide?
The HSE says the general public should never use biocidal products that are intended for professionals only, and professional users must hold certification for some of them. The law also says a biocide must be used as its authorisation and label allow. Ask any firm which product it uses and read the label for yourself before the work.
Do the gutters get cleared on the same visit?
Yes. Debris from the tiles lands in the gutters, so we clear the runs and flush the downpipes before we leave. We also look at the joints, brackets and falls. If the gutter itself is failing, we tell you, show you the photos and price any repair as one total, so the clean does not hide a gutter problem.
Can you clean a roof just before I sell?
Yes, and a dated set of photos after the clean helps if a buyer's surveyor raises the roof. We check the tiles as we go, so you hear about any fault before a buyer does. Build the work in before you list, because a repair found late can hold up a sale. Send us a photo and the house type for a price.
Is a roof clean a good time to fix other faults?
Often, since the access is already set up and the tiles are clean enough to read. We photograph any cracked tile, loose ridge or tired flashing, explain it, and quote the repair as a single written total before work starts. You decide whether we do it then or later, and nothing is added without your agreement.
Show us the slope with the most moss
Send a photo of the worst slope, taken from the ground, with the house type and whether the gutters overflow.