Everything You Need to Know About Roof Moss
Roof Moss Removal Price Guide For 2021
Products That Stop Moss Growing Back
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On many roofs, moss can be troublesome; it blocks gutters, rainwater pipes and even clogs up underground soakaways.
Patios, conservatory roofs and paths underneath the roof can also be covered in bits of moss that have been blown off the roof.
In extreme circumstances, it can also eat away at the surface of roof tiles where it accelerates the weathering process.
The good news is that any roofing professional should be able to remove roof moss and there are products that stop it growing back.
But how much does it cost to remove roof moss?
Is manual moss removal better than pressure washing?
Keep reading to explore our price guide and discover answers to common questions.
Note: The price guide on this page is for manual removal of roof moss, this type of project is completed with hand tools and brushes. To see our guide to roof power washing, check out our roof cleaning price guide.
Roof Moss Before and After Photos
These photos show what a difference manual roof moss removal can make to the appearance of a roof.
The moss on these roofs was removed with a scraper and brush, nothing else.
(Click to expand)
Project Schedule For Roof Moss Removal
Here’s a works schedule for roof moss removal:
- Raise platform access towers to the roof edge (this provides edge protection for workers on the roof as ladders cannot be used alone).
- Remove roof moss by way of scraping and brushing.
- Sweep down the roof to remove dust.
- Check the roof for cracked and broken tiles, replace them where needed.
- Clear out gutters and clean exterior of gutters.
- Check rainwater pipes to ground level and unblock as required.
- Spray the roof tiles with a fungicide treatment to kill off any moss spores which will deter the moss from growing back.
- Lower the access platforms and take away all waste.
We asked 34 roofing firms from various locations around the UK how much it would cost to remove moss from a roof and treat the tiles with a fungicide.
The roof is approximately 8 metres long and has two sides; front and rear.
The figures below are an average of the prices we received, we’ve also rounded the numbers to the nearest £50:
How to Stop Roof Moss Growing Back
Moss is spread by microscopic spores which grow incredibly fast when exposed to moisture.
They’re usually spread by the wind and they prefer shady damp areas, such as behind chimneys, on north-facing roofs and tiles located under trees.
Unless a fungicide is applied to the roof, these tiny spores from the removed moss will quickly start sprouting into new clumps of moss.
The fungicide kills off the microscopic spores on the roof, significantly slowing down the regrowth of moss.
The best fungicide for this is Benzalkonium Chloride, a chemical that’s widely used to prevent mould, moss and algae growth on surfaces and in products such as paints and sealants.
What Happens if a Fungicide Isn’t Applied?
The spores will start to grow as soon as they get wet, small sprouts of moss may form in a matter of weeks, especially if it’s winter.
More widespread moss growth will form in months, first on shaded parts of the roof and then spreading to all other areas.
How Long is the Fungicide Effective For?
Once the roof is demossed and treated with a fungicide, the moss shouldn’t grow back for several years.
On south-facing, sunny parts of the roof, the moss can take up to five years to take hold.
On damp, north-facing parts of the roof, the moss will grow back sooner, small amounts can be expected within two to three years and more prolific growth in four to five years.
How to Permanently Stop Roof Moss Growing Back
Despite some firms advertising expensive roof paints, coatings, sealants and elixirs that apparently stop moss growing, there is only one solution and it doesn’t involve any costly products.
Remove the moss once, treat the roof with a fungicide and reapply the fungicide every few years.
If the fungicide is reapplied before the moss has a chance to take hold, it can be kept in check perpetually.
There are tools and equipment that allow workers to spray a roof without even stepping foot on the roof; this reduces the cost of a retreatment considerably.
Extra Costs to Consider:
The prices on this page are for a straight-forward moss removal project.
You need to pay extra for:
Access Equipment – We’ve included the cost of access equipment in the form of tower platforms. However, some roofs may require a full scaffold system which would cost extra. If your roof is more than three or four storeys high, has a large conservatory underneath it or is otherwise difficult to access, the moss removal project will cost more.
More Substantial Repairs – When removing roof moss, contractors will check the roof for broken tiles and swap them for new ones. More substantial repairs, such as replacing a roof valley, will need to be priced separately.
Roof Size – Our prices are for an “up and over” roof, that you would typically find above a three-bed home. Larger roofs will take longer to clear of moss and cost more.
Tile Type – Moss can be removed from any roofing tile, and most roofs in the UK are covered with concrete tiles, these are tough and difficult damage. Clay tiles are less popular but are more fragile, and specialist access equipment might be needed to access the roof without breaking them.
Roof Moss Removal and Treatment
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Roof Moss FAQs
Why Can't The Fungicide Be Used to Remove the Moss?
The fungicide we recommend can kill the roof moss but the moss would still be on the roof. It could take months, maybe years, for the dead moss to decay. Rainwater would then wash it into the gutters, rainwater pipes and possibly the drainage soakaways where it would cause blockages.
The fungicide should be used as a surface biocide to clear the roof of spores once the bulk of the moss has been removed and disposed of.
I've Been Told That a Roof Coating, Paint or Sealant Will Stop Moss. Is This True?
Roof coatings and sealants can slow down the growth rate of moss that’s on the tile surface, but it won’t stop moss from growing in the gaps and overlaps between the tiles.
The close up photo below shows moss growing between the tiles, no amount of paint or sealant etc will stop this:
Why Can't This Type of Work Be Done From Ladders?
Can The Roof Be Coated or Sealed After The Moss Has Been Removed?
Paints, coatings and sealants should only be applied to surfaces that have been thoroughly cleaned. The surface should not contain any dust, contaminants or pollutants etc. that could prevent the product from adhering to the tiles correctly.
The only way to thoroughly clean roof tiles to this degree would be by pressure washing them. Demossing with a scraper and brush wouldn’t suffice.
Can Moss Be Removed From a Flat Roof?
Extra care will be needed when working on a flat roof as they’re more fragile than concrete tiles. Moss shouldn’t be scraped or power washed off a flat roof but if the roof is in good condition, one may be able to brush the moss off.
I've Been Given a Quote That is Considerably Higher/Lower Than The Figures on This Page. What Gives?
Our prices are for a two-sided roof above a three-bed home, they are a rounded average of prices given to us by 34 roofing firms.
If your price is significantly below this average, you may want to ask the roofer if they will be erecting edge protection. It’s not uncommon for roofers to complete this type of work from ladders even though they would be breaking the law. Some just walk on the roof with no protection whatsoever.
If the prices you’ve been given are much higher than our averaged price, it could be that you’ve sourced prices from a firm that has more overheads and needs to charge more. In general, the bigger the firm, the more they need to charge to make a profit.
We recommend sourcing at least three quotes from reputable roofers and comparing their work schedule and price to the information on this page.
Where Can I Find a Good Roofer?
The National Federation of Roofing Contractors and the Confederation of Roofing Contractors are well-known organisations that maintain databases of approved roofing contractors in the UK. The Competent Roofer scheme promotes roofers that agree to adhere to a high set of standards.
We’ve also partnered with Rated People – one of the best places online for finding vetted, reviewed and rated tradespeople.
How Long Does it Take to Remove Roof Moss?
For a straight-forward up-and-over roof, two workers can complete the project in around a day, perhaps a day and a half for a more complex roof. This includes the erecting and dismantling of edge protection towers.
For larger roofs, perhaps with three or four sides, the work will take between two and four days.
Extra time should be allowed for garages, porches, steep roofs or roofs that are difficult to access.
Does Moss Damage Roof Tiles?
The vast majority of roofs in the UK are covered with concrete tiles, and for the most part, these are strong enough to prevent any damage from moss.
In extreme circumstances, for example, when the roof is carpeted in moss, it may eat away at the surface, which essentially accelerates the weathering process.
On more fragile clay tiles, the extra moisture held by the moss can lead to an increased risk of damage in winter due to the freeze/thaw process.
While wet moss is heavy, the weight never threatens the structural integrity of the roof as it’s spread thinly.
What is the Best Way to Remove Roof Moss?
If your goal is to remove the roof moss and stop it from coming back, then either manual or power washing techniques will suffice.
If you need the roof to be cleaned rather than just demossed, perhaps because you want to apply a roof sealant or coating, then it should be power washed.
What Are The White Marks on Roof Tiles?
White marks on roof tiles are lichen, a slow-growing thin organism that’s very tough to remove.
The best way to remove it is by power washing or by treatment with a fungicide.
The fungicide requires time to work but 4-6 weeks after the application, most of the lichen should’ve disappeared.
We do not recommend trying to remove lichen with scrapers or wire brushes as they will scratch and scuff the tiles.
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Broken Roof Tiles
Discover how much roofers are charging to erect access equipment, go up on a roof and replace broken roof tiles. Also, get your own custom quote.
On this page, we reveal how much it costs for a pro to go up on a roof, clean the tiles and apply a protective coloured coating. This is a viable alternative to manual demossing but it costs much more.
Their prices for roofline installations were correct; we were given quotes from several firms, all were similar to [Quotaton Check’s]
Very few tradespeople provide price guides for their work, but Quotation Check has a database of prices based on estimates provided by tradespeople and companies.
Why only rely on three or four quotes for comparison? This website called Quotation Check gathered prices from hundreds of firms for various home improvement tasks and published their findings online.
Check how the quotes you’ve been given for home improvement projects compare to the national average – visit Quotation Check.
Go see the prices on the Quotation Checker website; they’re suggesting a price for a new roof that’s much lower than that.