How to Price Roof Cleaning and Moss Removal

Summary

Roof cleaning is one of the easiest jobs to underprice because the customer sees "a bit of green moss" and you see two visits, a scaffold or tower, a respirator, biocide chemicals, gutter clearance of the dislodged moss, and the bagging and tipping of the debris. The actual cleaning is maybe a third of the cost — access and labour-at-height make up the rest. A roof priced at £200 because "it only took two hours" almost always loses money once the access cost and the return biocide visit are counted.

There are three core methods and they price very differently. Manual scraping (physically removing moss with a scraper and stiff brush) is labour-heavy but safe for the tiles. Soft washing uses a low-pressure (sub-100 psi) application of a biocide solution that kills the moss and lets it weather off over weeks — gentle, premium-priced, and the method most warranty-conscious roofers prefer. High-pressure jet washing is fast and dramatic but is the method most likely to land you in a dispute: it strips the protective surface off concrete tiles, drives water under the laps, and can shatter aged slate. Many roofing bodies and tile manufacturers advise against pressure washing concrete and clay tiles for exactly this reason. Price the method you intend to use, and write the method into the quote.

This guide is for the tradesperson deciding what to charge: typical labour, current UK chemical and plant costs, day rates, margin, the red flags that change the price, and what to itemise. For the post-treatment biocide chemistry and die-back timing see moss treatment; for the gutter-clearing that always follows a roof clean see gutter cleaning and maintenance.

Key Facts

• Roofer / cleaning operative day rate — £180-£280 regional, £240-£360 London
• Two-man team day rate — £320-£520 regional, £420-£640 London
• Scaffold tower hire — £60-£120/day, £150-£280/week (DIY-erect) or £250-£450/week supplied-and-erected
• Full perimeter scaffold (semi) — £800-£1,800; (detached) £1,400-£3,000
• Cherry picker / MEWP hire — £180-£350/day + operator/IPAF, often £350-£550/day all-in
• Biocide concentrate — BPR-registered (e.g. benzalkonium chloride or DDAC based) £25-£60 for 5L concentrate, diluted typically 1:4 to 1:10; covers 100-250m²
• Pump sprayer / low-pressure soft-wash kit — knapsack £40-£90; powered soft-wash unit £400-£1,500 (capital, amortise across jobs)
• Roof area, 3-bed semi — typically 60-90m² of slope (both pitches)
• Roof area, detached — typically 100-160m²
• Scrape rate — a two-man team clears ~30-60m² of moss-heavy roof per day depending on density and access
• Soft-wash rate — application is fast (1m² in seconds); the cost is access and biocide, not the spraying
• Moss / debris waste — wet moss is heavy; a typical semi generates 4-12 bags; tipping £5-£15/bag or skip-share
• Waste carrier licence — required to transport the moss/debris off site: register with the Environment Agency (England), SEPA (Scotland) or Natural Resources Wales (Wales)
• Zinc / copper strips — £6-£12/m supplied; fitted along the ridge to suppress regrowth (slow-release metal salts)
• Gutter clearance — moss scraped off the roof ends up in the gutters; budget £80-£200 to clear and flush afterwards
• Optional re-coat / tile sealer — £8-£18/m² applied; controversial (can trap moisture) — quote as a separate, caveated line
• Work at Height Regulations 2005 — risk assessment and suitable access for any work where a fall could cause injury
• Biocidal Products Regulation (GB BPR / EU BPR) — only use products authorised for roof/hard-surface biocidal use; check the product is registered

Quick Reference Table

Detailed Guidance

Price the Access First, the Cleaning Second

The single biggest swing in a roof-cleaning quote is how you get on (or near) the roof. Decide the safe access method before you put a number on the cleaning, because it can double the price:

• Ladders + roof ladder — only for brief, low-risk work on a dry, low-pitch roof with a documented risk assessment. Fine for a bungalow or a quick biocide spray.
• Scaffold tower (£60-£120/day) — the practical minimum for a half-day to two-day scrape on a two-storey house.
• Full perimeter scaffold (£800-£1,800+) — needed when you are working across a whole elevation, walking the roof repeatedly, or the pitch/height makes a tower impractical. This is often the line that makes the job uneconomic at a "cheap" price.
• MEWP / cherry picker — useful for soft-wash-from-the-edge jobs where you never set foot on the tiles. Day rate plus an IPAF-ticketed operator.

Write the access on the quote as its own line. If the customer balks at the scaffold cost, that is a conversation to have up front — not a margin you quietly absorb.

Choosing the Method — and Pricing the Risk

              ROOF CLEANING METHOD SELECTOR
                        |
        +---------------+----------------+
        |                                |
  Concrete/clay tile               Slate / fragile
  or aged surface?                 / heavily mossed?
        |                                |
        | YES                            | YES
        v                                v
  AVOID high-pressure              Manual scrape (gentle)
  Use SOFT WASH or                 + biocide; never jet
  manual SCRAPE + biocide                  |
        |                                  |
        v                                  v
  Apply biocide, let            Biocide return visit
  moss die back 4-8 wks         after die-back if needed
  (see moss-treatment)

Manual scraping — physically removing moss before any wash. Labour-heavy: a two-man team manages roughly 30-60m² of dense moss per day. Safest for the tiles. Price the labour days plus access plus biocide plus waste.

Soft washing — low-pressure (typically under 100 psi) application of a BPR-registered biocide. The moss is killed in place and weathers off over 4-8 weeks; sometimes a light second pass is needed. Premium method, low tile risk, easy to apply but the value is in the chemistry and the warranty story, not the labour minutes. Price it on access + materials + a margin for the result, not on hours on site.

High-pressure jet washing — the one to be careful with. It is fast and the "before/after" looks impressive, but on concrete tiles it abrades the cement face (accelerating future moss growth), on clay it can craze the surface, and on aged slate it can crack and delaminate. It also drives water up under the laps and into the loft. If you offer it at all, offer it only on robust, sound surfaces, put the risks in writing, and never present it as the default. Many manufacturers and roofing bodies advise against pressure-washing tiled roofs — quote accordingly and protect yourself.

What to Itemise on the Quote

A defensible roof-cleaning quote separates the cost drivers so the customer can see what they are paying for and you are protected if scope changes:

1. Access — tower hire / scaffold / MEWP, with duration
2. Cleaning labour — number of operatives × days, method named (scrape / soft wash)
3. Biocide treatment — product, dilution, coverage; note whether one or two visits
4. Gutter clearance — clearing the dislodged moss that lands in the gutters
5. Waste removal — bagging and tipping, stated as included or separate
6. Optional extras — zinc/copper ridge strip, post-treatment return visit, sealer (caveated)
7. Margin / overhead — your standard mark-up on labour and materials

Naming the method in writing matters: if you quoted "soft wash + biocide" and the customer expected an instant jet-washed transformation, the written method is your defence.

Red Flags That Change the Price

• Brittle or aged concrete/clay tiles — heavy moss often hides cracked or delaminating tiles; walking them or jetting them causes breakages you'll be blamed for. Inspect and caveat. Replacement tiles + a roofer visit can add £150-£400.
• Slate — natural slate is brittle and old slate fixings (nails) may already be failing. Scrape gently, never jet, and warn that dislodged slates may need re-fixing.
• Steep pitch (>40°) or three storeys — access cost climbs steeply; full scaffold likely.
• Solar panels — must be worked around carefully; never jet near panel seals or cabling. Price the extra care time.
• Nesting birds — moss-heavy roofs and gutters can hold active nests in spring/summer; disturbing them can breach the Wildlife and Countryside Act 1981. Defer or work around.
• Bats — if there's any sign of a roost (droppings in the loft, gaps under tiles), bats are protected and work must stop pending advice. Major programme risk.
• Asbestos cement — old garage and outbuilding roofs may be asbestos cement; never scrape or jet these (see asbestos removal pricing guide).
• Render/painted walls below — biocide overspray and dirty run-off can stain rendered or painted walls; sheet up and price the protection time.

Worked Example — 3-Bed Semi, Scrape + Biocide, Tower Access, Regional

A typical mid-job that you'll quote often. Roof area ~75m², moderate-to-heavy north-facing moss, two-storey, tower access.

In practice you might trim the labour and present this nearer £650-£900 if the moss is lighter or the team is faster, but the structure shows why a "two hours, £200" mental model loses money: the access, the second-task gutter clearance, the waste and the margin are all real costs the customer doesn't see.

Margin and Repeat-Business Strategy

Roof cleaning is a relationship sale. The biocide doesn't give an instant result, so the customer who pays £700 and sees little change the next day needs managing — explain the 4-8 week die-back up front (see moss treatment). The upside is recurring revenue: offer an annual or biennial maintenance biocide-only return visit at £120-£280, which is high-margin because the access is light and there's no scraping. Pair it with a gutter clear and you have a tidy seasonal round. Target 20-30% net margin on the access-and-labour, more on the chemical and return visits.

Frequently Asked Questions

Should I ever use a high-pressure washer on a tiled roof?

Rarely, and never as the default. On sound, robust surfaces (some concrete tiles, hard standing) it can be acceptable at controlled pressure and distance, but on aged concrete it strips the surface, on clay it can craze, and on slate it cracks tiles and risks dislodging them. It also forces water under the laps. Most tile manufacturers and roofing bodies advise against pressure-washing roof tiles. If a customer demands it, put the risks and your disclaimer in writing, or decline.

How long until the moss actually disappears after a biocide?

With a BPR-registered biocide, moss and algae die back and weather off naturally over roughly 4-8 weeks, sometimes longer in dry spells. Manual scraping gives an instant visual result; soft washing does not. Set this expectation before you quote so the customer isn't disappointed on day one. See moss treatment for the chemistry and timing.

Do I need a licence to take the moss away?

Yes — to transport waste you remove from a customer's property you need to be a registered waste carrier with the Environment Agency (England), SEPA (Scotland) or Natural Resources Wales (Wales). Upper-tier registration is the norm for a trade carrying others' waste. Keep waste transfer notes. See waste disposal.

Is a sealer or roof coating worth quoting?

Tread carefully. Some "roof coatings" and sealers can trap moisture in concrete tiles and interfere with the roof's ability to dry, and the long-term performance claims vary widely. If you offer one, quote it as a clearly separate, caveated line rather than bundling it in. Many experienced roofers avoid them on porous tiled roofs entirely.

How do I price a roof I can't safely walk?

Don't price to walk it. Price for soft-wash-from-the-edge using a MEWP or extended lance from a scaffold/tower, where you never set foot on the tiles. The cost moves from labour-days to access plus biocide, and you avoid the breakage risk on brittle tiles entirely.

Regulations & Standards

• Work at Height Regulations 2005 — risk assessment, hierarchy of control (avoid > prevent > minimise), suitable equipment for any work where a fall could cause injury

• Control of Substances Hazardous to Health (COSHH) Regulations 2002 — assessment and safe handling of biocide chemicals

• GB Biocidal Products Regulation / EU Biocidal Products Regulation (BPR) — only use products authorised for the biocidal use claimed

• Wildlife and Countryside Act 1981 — protection of nesting birds; do not disturb active nests

• Conservation of Habitats and Species Regulations 2017 — protection of bats and roosts

• Environmental Protection Act 1990 / Waste (England and Wales) Regulations 2011 — duty of care and waste carrier registration

• HSE INDG401 — Working at height: a brief guide

• BS 5534:2014+A2:2018 — Code of practice for slating and tiling (relevant when cleaning reveals fixing defects)

• HSE — Working at height — health and safety duties

• HSE — Biocides and the Biocidal Products Regulation — authorised biocidal products

• GOV.UK — Register as a waste carrier — Environment Agency registration

• NFRC — National Federation of Roofing Contractors — roofing good practice

• Property Care Association — surface biocide and moisture guidance

• moss treatment — biocide chemistry, die-back timing, zinc strips, pressure-washing risks

• gutter cleaning and maintenance — clearing the dislodged moss that lands in gutters

• roof repair pricing guide — pricing repairs when cleaning reveals cracked tiles or flashing faults

• fascia soffit guttering pricing guide — pricing gutter and fascia work alongside a clean