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Asphalt roof type was discussed in our previos blog post. In this post we would be discussing some more roof types namely tile roofs, metal roofs and membrane roofs.


Here is an example of clay barrel tiles used for roofing. This is a popular look in states that border Mexico and the Gulf.
tile roof

The manufacture of tile roofing is represented by the Tile Roofing Institute, whose web page is

Clay tile is produced by baking molded clay into tile. The density of the clay is determined by the length of time and temperature at which it is heated. Tiles may be glazed and also may have surface texture treatments applied. As a result, there are a wide variety of tile profiles, styles, finishes and colors available. In addition, each tile may have separate field, ridge, hip, gable and terminal tiles of various shapes. Installation methods depend on the nature of the tile being installed; that is, whether it is two piece, one piece, interlocking or flat.

Concrete tiles are made of portland cement, sand and water in varying proportions. The material is mixed and extruded on molds under high pressure. The exposed surface of a tile may be finished with cementitious material colored with synthetic oxide additives. The tiles are cured to reach the required strength. They generally have lugs on their undersides for anchoring to batten strips. There are additional waterlocks or interlocking ribs on the longitudinal edges that impede movement and prevent water infiltration. As with clay tile, there are a wide variety of profiles, styles, finishes and colors available. Color may be added to the surface of a tile or dispersed throughout (color through). Special texture may be added in surface treatment.

The TRI does not suggest any particular cleaning method, but they reference the fact that cleaning may be necessary. A check of some manufacturers finds instructions like: What is the best solution to use forcleaning roof tile? Common household bleach at no more than 1% strength should kill most of the algae spores.

Contractors have tried to clean using solutions of just 1% concentration without good results. Repeating what we said before, we find we can make a solution in the range of 3%-6% concentration and have an effective cleaner without altering the integrity of a tile roof.

The other element to creating a cleaning solution like this is that it should contain some soap. We strongly suggest that adding a surfactant (detergent) to your roof cleaning solution will minimize how much of that solution you have to use overall.


The Metal Construction Association promotes metal roofing. They certify properly manufactured roofing panels. The Metal Roofing Alliance also promotes metal roofing materials for residential and commercial use.

Typical metal roofs are either shingles or panels, and may be bare or painted. The most common metal roofing consists of metal panels that are painted in an architectural color.

The drawback to cleaning a painted roof comes from the paint itself. Paint subjected to intense sunlight and pollution may fade, pit, or discolor. Since any algae or soil on the surface of the paint cannot root down into the paint, we found that lighter concentrations of bleach and soap (in the range of .5% – 1.0% sodium hypochlorite) gives the best cleaning with the least amount of risk to the paint.

Copper roofs are different. The most common complaint about the appearance of copper roofing is about ‘patina’ or fingerprints, and acid-based cleaners are excellent for restoring the original look of copper.


Membranes are sheets of flexible rubber-like material used for roofing. Limited to mostly flat industrial roofing where the membrane is covered with stone, membrane roofs are rarely cleaned.


The National Slate Association is a resource for roofing professionals, architects, builders and property owners for slate roofing materials. Since slate roofing is made from metamorphic rock, it will not saturate with water, and it is completely fireproof, making it a great material for homes in areas subject to wildfires. Since it is a natural stone it also has extremely long life expectancy, as long as 100 years!
Slate roofing

There are many other types of roofing materials used in construction today, but regardless of what they are made of, all of them can become a breeding ground for mold and algae growth.