Roof cleaning is essential maintenance, and can help prevent costly repairs and increase the lifespan of your roof. While pressure washers are a popular and efficient way of cleaning roof tiles, the high pressure can be too harsh for roof tiles, especially those made from certain materials. There are alternative, more gentle methods to wash roofs that will still clean well, but won't cause any damage.
Pressure washing works. It uses a motor to pump water through a high-pressure hose and out through a narrow nozzle. The resulting water stream is powerful, high-velocity, and much more intense than a standard garden hose. It can efficiently and effectively lift dirt, grime, oil, and organic growth from surfaces. So why shouldn't you use one?
A pressure washer is perfect for cleaning large, durable surfaces, but roofs are surprisingly fragile. A tile roof is laid very carefully, with overlapping tiles that precisely direct water, preventing leaks.
A pressure washer can lift or damage tiles, and this prevents this pattern from working as it should. Instead, water can penetrate between the tiles and enter the roof structure.
This is especially a problem for older, more fragile tiles, or for certain tile materials like clay or concrete.
If water is able to penetrate the roof beneath, it can cause wide-ranging issues for the property. This includes leaks and mould growth. In extreme cases, it can even damage the structural integrity of the entire roof. If water causes the wooden elements of the structure, like the rafters and the decking, to rot, they can start to degrade and sag. This will require extensive repair work to restore the roof's integrity.
Most roofs are covered by two warranties. The manufacturer's warranty covers the materials used to build the roof, and the workmanship warranty covers the installation from your roofing company.
Both using a pressure washer and cleaning your roof as a DIY job will void both warranties. So if you do cause any damage, it won't be covered, and you will have to pay the money to fix it out of your own pocket.
A pressure wash uses a large amount of water, and the run-off from it will be equally big. There is nowhere else for it to go but the surrounding ground. This water will be full of dirt, contaminants, and harmful chemicals (if a chemical cleaning solution has been used).
It will then drain into local waterways, and could contaminate nearby plants.
Before taking you through our step-by-step guide for cleaning a roof without a pressure washer, we should emphasise that cleaning roof tiles yourself is not always the best idea.
Any type of work at height is dangerous, and roof cleaning is especially so. Being up high while using water carries a real and present risk of slips and falls. Professional roof cleaners have had specific training in how to clean roofs safely, and will have all of the necessary safety equipment to keep themselves safe.
Even without the use of a pressure washer, you also run the risk of accidentally damaging your tile roof. Scrubbing too hard, using the wrong chemicals, or overheating with a steam cleaner can damage roof tiles and lead to water ingress.
First, you will need to gather all the equipment you need.
You should clean your roof on a dry, cloudy day. Rain will make it less safe, but the sun will evaporate any cleaning solution you use too quickly for it to be effective.
You should always inspect the roof for damage before starting to clean. If there are damaged tiles or other roof elements, you could worsen the problem with scraping, scrubbing, or excess water.
If you do notice any damage, contact a roofing company to get it repaired before you clean the roof.
Use a broom or a leaf blower to clear leaves, twigs, and other debris from the roof. Be as gentle as you can to avoid damaging the tiles.
If you notice any loose debris gathering in the gutters, make sure that these are cleared.
If you have moss growth on your roof, this will need to be removed. Moss-killing chemicals are the quickest and easiest method.
Apply the solution to any moss and algae growth according to the manufacturer's instructions. You can either do this manually using a brush or with a sprayer. Leave it to sit for as long as directed, and then rinse with a garden hose.
Now you will need to remove the roof moss using manual scrubbing. Take a stiff brush and work your way from the top down, scrubbing the moss from the roof tiles. If there are any stubborn areas, you can use a trowel or scraper.
Remember to be gentle to avoid lifting or damaging the roof tiles. Once the moss has been removed, you can dispose of it in your compost or garden waste bin.
Once you have removed the moss, you may want to clean the roof tiles again.
First, apply a cleaning solution. You can use a shop-bought specific roof cleaner, or you could use a vinegar-water mix, or a mild detergent.
Apply the cleaner using a brush or a sprayer. It should be applied evenly, covering the entire roof. Leave it to sit for 20-30 minutes.
As with moss removal, scrub gently starting at the top of the roof and working your way down. Focus on areas with visible staining or any remaining moss.
Rinse with a garden hose. A hose uses much less force than a high-powered pressure washer and won't cause damage to the roof tiles. Even so, avoid focusing on one area for too long.
Read our article on "How to clean a roof professionally".
Steam cleaning can both remove moss and clean roof tiles. It is a safer alternative than pressure washing for tile roofs because it is less likely to damage the roof surface.
It heats water to produce high-temperature steam, which is then directed through a nozzle to target specific areas. The high heat kills moss and algae, and it also makes the roof clean by lifting and loosening dirt.
Once the entire roof has been steamed, you can then rinse the loose dirt and moss off using a garden hose. Start at the top of the roof and work downwards to avoid water pooling.
Once you have cleaned your roof, there are some steps you can take to protect it in the future. These steps will help to prevent damage and extend the lifespan of your roof.
Once you have removed all of the moss and algae from your roof, you can stop it from coming back using a few different methods. Algae-resistant coatings can prevent it from taking root in the first place, while placing copper or zinc strips around the edges of the roof inhibit moss growth and kill any moss present.
Learn more from our post "How to clean roof moss".
Regular gutter cleaning has a big impact on protecting your roof. Leaves and other debris can clog gutters, and this prevents the roof drainage from working as it should. The result is pooling water, which can degrade roof tiles and lead to leaks, and an increased risk of moss growth.
A roof coating can help to waterproof your roof, prevent organic growth, and protect the tiles from UV damage.
Don't miss our post "Does roof coating stop leaks".
A regular cleaning schedule will ensure that your tile roof is kept clean and protected from damage.
If your roof is covered in moss or is otherwise dirty, we can help. Our professional roof cleaning services ensure that your roof is cleaned to a high standard, while also protecting the tiles from damage. Our team is experienced in using all types of roof cleaning methods, and are highly effective at cleaning without a pressure washer. We are dedicated to ensuring that your roof is in the best condition it can be for the longest amount of time.
Roof tile manufacturers did not design their tiles with pressure washers in mind. While in some situations, pressure washing can be an effective and efficient method, it carries with it a risk of damage for certain types of roof tiles. There are various alternative methods that are just as effective at cleaning, while protecting the integrity of your roof.
