Last Updated on February 15, 2024 by Kimberly Crawford
When roof cleaning, you should never use a pressure washer on roof tiles as it may cause damage to them. Your roof tiles have been made to last for 100 years and if the tiles are slate or concrete the last thing that you want to do as a homeowner is to decrease their life expectancy with a quick spring clean.
There are several reasons why you may be considering roof cleaning, and there are solutions other than power washing.
Reasons that you May Want to Power Wash Your Roof
- To remove built-up moss and unsightly lichen
- To prepare the roof for a sealant
- To make the roof look new
- To prepare the roof for painting
Moss growth is normally not harmful to the roof, and on really old roofs it can even look attractive unless it affects drainage and causes the roof to leak (check insurance info on leaks).
If a leak does occur water can invade the roof space, and it would then be necessary to remove the moss. Power washing is actually a bit too robust for a tile roof. Some councils have now issued bulletins to alert the residents to the fact that power washing can damage the roof tiles.
They go on to say that there are other ways of cleaning and brightening a roof without power washing.
Moss Build up on the Roof
If the roof has moss build-up that is highly unsightly, you may want to remove it yourself. In fact, the moss can be soaked in vinegar, which will kill it, and then it will easily scrape off. Only consider working on the roof if you are young and healthy, the older person should not be climbing on the roof. It is better to have someone do the job for you and to avoid scams always get three quotes first.
If the moss is removed from the roof, it will be easier to hose the roof down without using high pressure. Of course, if it is a thatched roof, you can’t use water at all. If your roof is accessible and you are the person going up there you are required to wear a safety harness, roof cleaning is dangerous work, made easier if the roof is accessible. A ladder is also necessary and a second person on the ground to keep the ladder stable.
If you get a company to clean a second-story roof you will require scaffolding and a platform under the ‘Working at Heights ‘law.
Try not to work in winter as the roof may be frozen, and the light low.
When You Use a Contractor for Roof Cleaning
- The contractor gives a written quote and conducts a risk assessment
- Erects scaffolding
- Protects the garden with plastic or a tarpaulin
- Disconnects downpipes and gutters
- Looks for broken tiles
- Check the condition of cement tiles.
- Treat the roof with a safe weed spray, allowing time for drying.
- Scrapes excess moss off the roof, killing any residual moss and lichen.
- Cleans the gutters, removing any dead birds and leaves.
- Scrapes and hoses down the roof.
- Flushes out the gutters, and reconnects them
- Repairs any cement cracks
- May apply a sealant to the roof tiles
- Disposes of the rubbish
- Cleans up the area
- Guarantees his/her work
As you can see it is quite a big job, but the reality is it won’t require doing too often. The job will be priced accordingly, and won’t need doing again for years. It is worthwhile looking for recommendations when getting this type of tradesman to come to your home, so ask the neighbors if they are able to recommend anyone. If you opt to do the job yourself, always have someone with you when working at heights.
Roof Cleaning
When we have lived in a house for a while, we don’t always notice what is happening on the roof. Birds stand on the roof in the sun, and when they excrete seeds onto the roof area, some of the plants actually grow and take root there.
When moss grows, it can attract insects and the lichens and moss are sustained through the regular rain events in the UK. Some vegetation growing on the roof is unavoidable, as the moss gets larger bits will break off and will roll into the gutter blocking the outlet.
How Often Should I do the Roof Cleaning?
The answer varies from place to place, and if your house is shaded by numerous large trees, it is the ideal environment for algae and fungi to grow. Because the trees shade the roof, and debris falls on the area the leaves trap the moisture on the roof allowing moisture to remain, and you need to clean off the roof annually, following ‘fall’ to avoid leaks later.
Leaf debris is heavy, creating a mulch on the roof and it needs to be cleared away allowing the roof to dry out. If your roof is fairly flat, roof cleaning can be as simple as getting up there with a broom and sweeping away all the leaves. If it is a steep roof you may need someone to come and do it for you.
Other Factors in Roof Cleaning
Snow, if snow sits on top of your roof for a long time it may damage the tiles. Snow is extremely heavy, and once the weather fines up again it stops snowing. Get someone up there to sweep it all off as if it is allowed to lie there the roof could begin to leak. Sometimes following winter storms there can be a shingle missing, so it is a good idea to check your roof annually, even if you don’t clean it.
Does pressure washing damage your roof?
Power-washing a roof has been the trend. Many gutter cleaners and even pressure washing companies offer roof cleaning as an additional service. If you’re not careful, however, power-washing your roof can do more damage than good.
Before you crank up that power washer, here are some things to think about:
What kind of roof do you have?
Pressure washing a cedar shake, tile or metal roof could cause damage to the shingles or tiles. A power washer can force water under shingles and loosen them from the nails. Tile roofs are fragile and may crack if they’re hit with a pressure washer too hard. The force of power-washing a metal roof can take off paint and loosen screws.
If you suspect that your roof is in bad shape, call in an expert. Many contractors offer inspections; if you hire them to do the work, they will probably use a pressure washer when cleaning your gutters (unless you specifically ask them not to).
Can you wash the roof yourself?
You can save a few bucks and rent a pressure washer. But before you do, check with your insurance agent to find out if getting your roof power-washed will mean higher premiums for homeowners’ insurance; some insurers don’t like it when roofs get washed.
Also, if you plan on hiring a contractor to power-wash your home, make sure the company has insurance to cover any damage that might be caused by their equipment or crew.
Pressure washers can also gouge concrete and brick surfaces, erode hardwood decks and strip paint from siding. They should never be aimed at aluminum siding because they can damage it. Be sure you understand how to properly operate the pressure washer.
If you decide it’s safe, start by diluting any dishwashing or laundry detergent in a bucket of water. Apply the solution with a garden sprayer and rinse it off after five minutes. Repeat this application if your roof is very dirty.
Don’t forget about your plants. Applying any detergents or cleaners to your roof can harm the root systems of plants around the house.
So, before you start pressure-washing your roof, make sure you understand all the risks involved. You might be safer doing it yourself or hiring someone with experience instead of renting a machine and taking matters into your own hands.
Can you power wash moss off a roof?
Yes, power washers and pressure washers can be used to remove moss. However, you need to take precautions before you start discharging a potentially harmful stream of water at your house.
There are certain types of roofs that should not be power washed; for example, if the roof is made out of metal, tile or natural-gas heating pipes, then it should not be power washed by an untrained person.
If you’re worried about your roof’s ability to withstand the pressure of a power washer feel free to call in a professional and discuss the best way forward with them.
How long does it take to power wash a roof?
Typically, it takes five hours to power wash a roof.
The average cost is about $1 per square foot for the service. For most roofs, if there are no trees hanging over it or obstacles blocking the water from rinsing down your gutters, it only takes about half an hour to rinse off the soap mixture.
Can roof shingles be power washed?
Yes, power washers can be used to clean shingles. However, if they are older or very dirty power washing might not remove them completely.
If you use too strong of a jet spray when cleaning shingles you could damage their texture, rendering them more susceptible to the elements. For the best results on roof shingles it’s best to use baking soda as a mix with some dishwashing detergent and warm water.
How much does it cost to power wash a roof?
Pressure washers can be rented for $15 to $35 per day.
A professional might charge $1 to $2 per square foot ($100 – $200 for an average home that is about 2,000 sq ft.). You will spend less if you do it yourself with a pressure washer.
So Should You Power Wash Your Roof?
No not normally, as it can damage your tiles. If a tile is missing you need to know about it immediately and get it replaced. So from that point of view, it is a good idea to have your roof expert take a look at it annually, and make necessary repairs. Now we have drones and every year the drone can film the top of your building remotely, then you receive a copy of the footage, saving climbing up!!
