How to Clean Tile Roofs (Pressure Washing Recap)

How do I clean my tile roof?

This is the question that everyone asks; whether it’s when they get a notice from their Homeowner’s Association or just see that their roof is dirty and want to have it cleaned. In an attempt to not confuse the heck out of you, we’re going to simplify the different processes out there into three different categories: soft or low-pressure wash, high pressure washing, and delayed rain-activated cleaning.

Today, we are going to look at high pressure washing. Over the past 15 years, this method of pressure cleaning has been the most popular. It’s also by far the cheapest (initial cost) of the three options. The reason is that there are so many people performing this service and all you need is a ladder, pressure washer, trailer, and business license. So, from a supply-and-demand standpoint, you can get your roof cleaned for less money than the other options.

The Problem with High Pressure Washing

The issue with this process is the potential damage that can be done to the roof. We get calls all the time to come out and clean roofs that used to be cleaned by pressure washers. Just 2 months ago, we did 36 large buildings in Cape Coral that had 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 worked with some homes in Naples that were all worth over one million dollars. The owners called us because they suspected the prior pressure washers weren’t that good and they wanted someone who wouldn’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 repaired. It cost the homeowner $5,000 to get them replaced – and the colors didn’t exactly match. To use high pressure washing, you have to walk the entire roof to clean it.

What Tile Manufacturers Recommend

Still not convinced? Let’s look at what the major tile manufacturers recommend. The biggest cement tile manufacturers for homes in Southwest Florida are Entegra, Hanson, Boral, and Eagle. You can go to any of their websites and look through their customer care information. All of them say the exact same thing.

Stated in the Entegra warranty: “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 1-to-2 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.

See also: Boral Roofing Warranty & Eagle Roofing Glossary.

Causing Damage, Mold, & Mildew

Most commercial pressure washers operate at about 4,000 psi. Have you seen how most pressure washers clean the tiles? They keep the tip of the nozzle inches from the surface at 4,000 psi (not 1-2 feet at 1,200). Their process is literally scraping the tiles and creating small dimples. Not only are they damaging the tiles (remember the tile manufacturer’s concerns), but these dimples are areas where moisture and dirt collects, causing the roof to get dirtier faster.

During HOA meetings, we often bring two brand new tiles. One, we run a pressure washer over using the common pressure washer method. The damage caused by just one cleaning is incredible. You can see that any sealant that was on is now mostly gone and there are millions of little dimples on 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 use high pressure cleaning on a roof, you’re 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 cause significant vibration to the roof. If the underlayment is weak or cracks over time, the vibration can cause further cracking that can also lead to leads.

We’ve had numerous customers that have sustained significant leaks after getting their roof cleaned via high pressure washing. It doesn’t happen all the time, but it seems to be especially an issue with older roofs.

Save Money: Hire a Professional

Pressure washers themselves 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 not only on the tiles, but the underlayment as well, is critical.

More and more homeowners and HOAs have come to the conclusion that technology and techniques have changed and potential damage from this process is not worth the potential “upfront” savings. In the long run, it’s always better to hire a professional that will use the right products and methods to protect your investment.