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This article will help you understand the best methods for cleaning roof tiles, including the processes involved for removing algae, slimes, lichens & moss from roof tiles.
Floorseal has two roof cleaning products which can be used independently of each other. Or as part of a more in depth method of cleaning by using them concurrently.
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Moss, algae, and lichens not only detract from your roof’s appearance but also retain moisture, which accelerates roof wear and damages underlying materials, this can lead to issues with damp and mildew inside the house. A build-up of moss can also clog gutters causing water to back up and overspill onto general masonry. Roof cleaning prevents long-term issues while maintaining the appearance of your roof and keeps gutters clear of moss.
This will vary depending on the type of roof tile, orientation (facing North or South), being surrounded by trees, general climate & age. Roofs will commonly suffer from moss, algae, fungi, & lichens. All of which can be removed with a cleaning solution.
Deciding between a DIY approach and hiring a professional depends on factors such as the roof’s condition and access to the roof. Roof bio washes can be applied using a pump-up sprayer and are the most cost-effective approach. A professional may follow the same approach as a DIYer but can be quicker!
Factors which influence how you clean a roof are – How much effort you wish to put into cleaning the roof and also if you wish to see immediate effects of cleaning. Or whether you are willing for a (residual action) cleaning product to work over a period of time i.e. weeks/months. The roof may be fragile or at a very steep angle preventing easy access.
All these factors will affect the decision as to how to clean your roof. You may not wish to scrape the roof. Alternatively you may need to scrape the roof due to very heavy build-up of organic matter & to produce the cleanest finish possible. You can also follow up with a residual effect cleaner which keeps the roof ‘cleaner’ for longer.
Floorseal Roof Cleaner Bio Wash – A residual action biocidal roof cleaner. The most cost effective product and easiest way to clean roofs. Dilute with water at 1:5 (general cleaning) or 1:3 (for heavy contaminations) then spray over the surface and leave it to work. This product continues to act for several months, up to approximately one year. This product does not require rinsing, only apply to dry surfaces. Typically used as a process to remove green organic matter, slimes, lichen & algae. This product will act over time continuing to remove (& resist regrowth of) lichens, moss & algae.
Floorseal Roof Cleaner Rapid A faster acting product which will make the roof seem cleaner at the end of the process, you will see a more immediate result. Apply at 1:1, rinse off after use. This product is can be used on damp days and can be applied to damp or wet surfaces. Can be used at full strength.
You can still spray over the surface (once fully cleaned with Roof Cleaner Rapid) with Roof Cleaner Bio Wash to keep the surface ‘cleaner’ for longer. This follow up treatment resists regrowth of organic matter.
It depends on what you are trying to achieve and the time you have to carry out the work. Is it heavily contaminated with moss? & can you access the roof? Is it fragile, a steep angle and are you happy to allow a cleaning product to do the work over time? Or do you want immediate results? There are three methods of cleaning a roof below to help you decide how to clean your roof.
Simply dilute Roof Cleaner Bio Wash at 1:5 or 1:3 and spray over the roof. This 1st method does not involve scraping green organic debris or making full access to the roof. You can apply with a simple low pressure pump-up sprayer.
Spray the surface with the solution at around 1 litre of product (after dilution) covering approximately 5m2 of surface area. Be liberal with the product spray the entire roof evenly, do not just patch spray. Leave the product to take affect on the contaminations over the next weeks/months (up to a year). Organic contaminations will slowly die/disappear, allow clumps of matter disintegrate /drop away over a period of time. The tiles should become ‘cleaner’ over the following weeks/months. You can repeat once or possibly twice per year.
5 litres of concentrate covers approximately 120m2 (or more) at a dilution rate of 1:5. Roof Cleaner Bio Wash will have no negative impact on tiles, lead flashing, glass or UPVC frames.
Follow the process as per option 1, but scrape the debris or clumps of any organic matter from the roof before treating. Scraping can be beneficial on really heavy build-ups of organic matter. Or because a contractor has been instructed to do this by the homeowner or main contractor. Possibly because the roof may appear cleaner before work starts on treating the tiles.
Then follow the 1st method as noted above.
This method of cleaning your roof will probably mean scraping the roof if moss is present. If moss is not present you may be able to proceed immediately.
Scrape the roof (if required) and apply Roof Cleaner Rapid at a dilution rate of 1:1 (can be used undiluted on very heavily contaminated surfaces) and allow to dwell on the tiles for at least 15 minutes. You will need to keep the surface wet (by applying more product) to prevent premature drying. You can extend this dwell time for as long as is required to remove organic staining. Particularly black and white spot lichens. Rinse off after use. Avoid lead flashing and UPVC, rinse well if contact is made with these surfaces.
Obviously you will need access to the roof to scrape. Sometimes when working on fine grained clay tiles, the moss will slide off by steaming or rinsing with a hose pipe.
You should see an immediate change through the course of the process. This method is more labour intensive but can rapidly create a dramatic change in appearance. It is particularly effective on black lichens and heavy lichen staining/contaminations.
Roof cleaning companies will sometimes follow this process to produce a very clean roof that is apparent as the work is being carried out. It’s a lot more labour intensive/costly.
5 Litres of Roof Cleaner Rapid can cover up to a maximum of 40m2 of surface area when applied at 1:1.
*The final variation on option 3 is to overspray with Roof Cleaner Bio Wash after treating the roof with Roof Cleaner Rapid to make the ‘clean’ last longer. This is the most involved method of cleaning a roof as you are often scraping the roof, cleaning with Roof Cleaner Rapid followed by a Roof Cleaner Bio Wash to make the clean last longer and/or to remove really ingrained organic contaminations.
The products are safe to use on all tile type including concrete, clay, composites, natural stone, marley tiles & more. Natural stone’s including slate, general sandstone, granite, limestone, Indian sandstone & York stone.
For the best results apply using a low pressure pump up sprayer. It is possible to purchase telescopic lances for some sprayers, if no access to the roof can be made (or desired). Generally no specialist equipment is required to clean your roof.
You should not need to use abrasion when using either product. It is the product which does the work. Possibly light agitation is beneficial when using Roof Cleaner Rapid but not crucial.
Floorseal Roof Cleaner Bio Wash is an easy to use residual action cleaner. Spray directly onto the surface and leave to work. Cheap and easy to apply, dilute at 1:5 or 1:3 with clean water. Can be applied at any time of year. No particular skill is required to use this product. Spray at 1 litre of product (after dilution) over 5m2 of surface area. Just saturate the surface and leave it to dry/work over weeks/months. 5 litres of concentrate covers 120m2 of surface area (or more). You can pre-scape the roof of any clumps of organic matter (or not depending on individual preference). Many DIYers do not pre-scrape as it will mean accessing the roof. Using this product following the ‘option 1’ method of roof cleaning above is the easiest/most popular way to clean a roof.
Floorseal Roof Cleaner Rapid provides a more immediate visible result very effective on black/white lichen. Requires some dwell time and rinsing. Avoid lead flashing & UPVC. Will make an obvious change to the surface providing a more obvious/immediate clean. Using this product is a little more labour intensive. 5 litres of concentrate covers up to a maximum of 40m2. The roof can be pre-scraped (or not) depending individual preference. Many DIYers do not pre-scape as it will mean accessing the roof. Roof Cleaner Rapid can be followed up with an overspray of Roof Cleaner Bio Wash to inhibit regrowth.
Floorseal Roof Sealer a breathable impregnating sealer for use on porous roof tiles. Can be applied after cleaning, when the surface is dry. The roof can still have Roof Cleaner Bio Wash applied again at a later date to help to maintain. 5 litres covers from 25m2 upwards (surface type dependent).
Only apply a sealer in dry conditions, typically from spring to Autumn. Cleaning roofs is carried out with either of the cleaning products above all year round.
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View our handy in depth Guide to Sealing Roofs
The information contained in this article is not exhaustive. If you need further information please contact Floorseal at info@floorseal.co.uk
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