Metal roofs are beautiful and durable, but they need regular cleaning just like any other type of roof. Dirt, debris, tree sap, and algae will all build up on the surface of a metal roof. Regular cleaning is also important to prevent algae and mildew from eating away at the protective coating. However, a metal roof requires some special care in order to avoid damaging the roof. When you're cleaning your metal roof, here are three things that you should never do in order to avoid damaging your roof.
1. Stepping Onto Your Metal Roof
Homeowners should stay off their metal roof when they're cleaning it. The first reason is that metal roofs aren't designed to hold the weight of the average person. You can easily cause dents in the roof or cause it to warp by walking in the wrong areas. You can also depress the metal panels far enough to slightly loosen the screws holding them into your decking.
The second reason is that metal roofs are dangerous and slippery even when they are dry. When you're cleaning your metal roof with water and detergent, they quickly become nearly impossible to safely walk on. Experienced roofing contractors have special footwear and safety equipment that make working on a metal roof manageable. They also know where to step on the roof and how to distribute weight to avoid causing damage.
2. Cleaning the Roof With a Pressure Washer
High-powered pressure washers are generally used to scour off the outer layer of a surface, which rapidly cleans it. The problem with using a pressure washer on a metal roof is that the outer layer performs a very important protective function—it's the reason why the metal roof resists rust. This layer may be paint, a protective coating or a thin layer of galvanized metal. When you scour off this layer with a high-powered pressure washer, it exposes the metal underneath. Your metal roof will begin to rust due to rain and humidity, which can quickly damage its integrity.
3. Using Harsh Cleaners or Leaving Cleaner on the Roof
When you clean your metal roof, you should use a very gentle cleaner and make sure it's highly diluted. If you know who manufactured your metal roof, follow the manufacturer's instructions on what cleaner to use. Otherwise, trisodium phosphate is a good choice. Use diluted ammonia to clean any mold or mildew from the roof. Attach a nozzle with a soap dispenser to your garden hose, add diluted trisodium phosphate or ammonia to the dispenser, and then spray the cleaner onto your metal roof. Use a soft-bristled brush attached to a long pole to scrub away any dirt or mildew on the roof, then rinse the roof clean with plain water. Harsh cleaners can corrode your metal roof, so you don't want to use too much cleaning solution, and you should rinse your roof well with plain water after cleaning it.
If you find that your metal roof is difficult to clean, call a roofing professional. Make sure that they have experience cleaning metal roofs—not all companies regularly service metal roofs, since they are rare in many parts of the country. Hiring an expert will ensure that your metal roof will be cleaned to perfection while leaving it undamaged.