How Do I Clean My Tile Roof? (Pressure Washing Recap)
This is the question that everyone asks when they either get a notice from their Home Owner’s Association or see that their roof is dirty and want to have it cleaned. In an attempt not to confuse the heck out of you I’m going to simplify the different processes out there into 3 different categories. Soft wash or low pressure, high pressure washing and delayed rain activated cleaning.
For this month’s blog we are going to look at high pressure washing which over the past 15 years has been the most popular. This is by far the cheapest (initial cost) of the three options. The reason is that there are a million guys performing this service and all you need is a ladder, a pressure washer and trailer and a business license. So from a supply and demand standpoint you can get your roof cleaned for less money than the other options. The issue with this process is the potential damage that can be done to the roof. We get called all the time to come out and clean roofs that used to be cleaned by pressure washers. Just two months ago we did 36 large buildings in Cape Coral that suffered over $200,000 in roof damage at the hands of the previous pressure washer…who is now out of business. It happens all the time. We did some homes in Naples that were all worth over $1,000,000. The owners called us because they suspected the prior pressure washers weren’t that good and they wanted someone who didn’t walk on the roof. When we sent our lift up above the roof it looked like a gorilla had been up there. We had to stop the job and have the owner contract with a roofer to get the tiles replaced. It cost the home owner about $5,000 to get them replaced…and the colors didn’t exactly match. To use this method you have to walk the entire roof to clean it.
Let’s look at what the tile manufacturers recommend. The biggest cement tile manufacturers for homes in SW are Entegra, Hanson, Boral and Eagle. You can go to any of their websites and look through their Customer Care information. All of them roughly say the exact same thing. I’ll quote from Entegra’s warranty language: “In most applications, a pressure cleaner set to 1200 psi should be used. The tip of the nozzle on the pressure cleaner should be kept approximately one to two feet from the tile. The limited pressure and large distance from the tile is to prevent damaging the surface of the tile.” They also highly suggest limiting roof traffic.
Entegra Roofing: http://www.entegra.com/media/documents/Maintenance_Guide.pdf#zoom=80
Eagle Roofing: https://eagleroofing.com/glossary/
Most commercial pressure washers operate at about 4,000 psi. Have you even seen how most pressure washers clean the tiles? See the above picture. The tip of the nozzle is about 6 inches from the surface at 4,000 psi not 1-2 feet at 1,200. They are literally scrapping the tiles and creating little dimples in the tiles. Not only are they damaging the tiles (i.e. remember the tile manufacturer’s concerns) but these dimples are areas where moisture and dirt collect thus causing the roof to get dirtier faster. I have two brand new tiles that I sometime bring to HOA meetings. One I run a pressure washer over using the common pressure washer method. The difference in just one cleaning is amazing. You can see that any sealant that was on is now mostly gone and there are millions of little dimples in the tiles.
Besides the typical visible damage you can sustain when pressure washing like broken, cracked or chipped tiles, there is another type of damage that can be even more costly. When you pressure wash a roof you are going to need to walk the entire surface to get it cleaned. The vibration from high pressure guns and some of the equipment that is used can caused significant vibration to the roof. If the underlayment is weak or crack over time, the vibration can cause further cracking that can also lead to leaks. I've had numerous customers that have sustained significant leaks after getting their roof cleaned via pressure washing. It doesn't happen all the time but seems to be an issue with older roofs.
Pressure washers are not the issue. We actually use several of them for cleaning ground work or exteriors of buildings. How the equipment is used and the potential damage it can have on not only the tiles, but the underlayment is critical. More and more home owners and HOAs have come to the conclusion that technology and techniques have changed and potential damage from this process on the roof is not worth the potential “up front” savings.