Yes roofs can be cleaned, and yes, it’s a real thing. Roof cleaning may actually be a wise investment to prolong the life of your roof. Overgrowth of moss, grime, lichen or algae can all shorten the life of your roof. If you have black streaks growing on your roof, they are likely caused by gloeocapsa magma algae spores that have landed on your roof and taken up residence. Once the algae has grown into streaks, the organism has usually been growing for several months and it’s high time to have it removed. If you live in a rainy part of the country, such as the Pacific Northwest, there’s a good chance you’ll find moss growing on your roof at some point. The northern part of your roof, as well as any parts that remain shaded all day, will provide a wet, cool haven for moss to flourish. Unfortunately this water-absorbing moss can damage your shingle roof, leading to rot if not removed. Beyond roof health and function, a clean roof can boost your curb appeal and potentially boost your home’s resale value. The national average for roof cleaning costs ranges between $270 and $350, although prices can be higher depending on how large your roof is, how steep your roof is, and what type of cleaning is necessary. Typically pros use either a pressure wash or chemical wash (made with a concentrated bleach solution) to remove algae, lichen, moss and dirt.
Over time, algae, moss, lichen, dirt and even salt (if you’re near the ocean) can build up on your roof. These buildups can affect the look and function of your roof unless removed. The buildup of organic materials such as moss on a shingle roof can prevent water from sloughing off as it normally would. Trapped water can rot the roof or cause early deterioration of your shingles. Even if you don’t have a shingle roof, moss and lichen absorb water, and that wet material adds weight and stress to your roof — as well as providing a home for insects and other pests, and collecting dirt. For reflective, cool roofs that redirect heat away from the home, algae and moss growths can hamper their ability to deflect the sun, which can affect utility bills. Visually, moss, dirt and algae growths on a roof can have a negative effect on perceived home value and curb appeal. For example, black algae streaks on your roof may cause a potential homebuyer to assume that the roof might need repair or replacement, when it only needs to be cleaned.
The national average for roof cleaning costs ranges between $270 and $350. Factors that can affect the cost to clean your roof are the height of your house, the size and pitch (steepness) of your roof, and the complexity of your roof’s design and accessibility. Geographic location also plays a role in roof cleaning costs as regional labor rates and area costs to do business will vary. There are several ways to clean a roof. The most common is pressure washing. Industrial pressure washers can spray over 3,000 pounds per square inch (psi) of water — which is much too powerful for roof cleaning, and may tear off shingles and damage your roof. Confirm that the roof-cleaning pro you choose will only use a low-pressure sprayer to protect your roof investment. For large algae or moss growths, pros often recommend a combination of low-pressure washing with a bleach-based chemical solution. This is referred to soft washing and should handily remove any growths taking over your roof.
Metal roofs are durable, environmentally friendly, safe and budget-friendly. If you’re considering an update, metal roofing installation doesn’t have to mean completely removing your old roof. In many cases, metal roofing can be installed over your existing shingles. Research building codes in your state, as many require that after two roofs have been installed, all roofing materials must be completely removed before a third roof can be put on. This protects your home’s structural integrity and your family’s safety. Carefully read contractor reviews and choose someone with extensive experience with metal roofing installation. One concern when installing metal over shingles is that over time, condensation can build on the shingles and cause the metal to rust. This will lead to rust around the panels, making them more likely to come loose in a storm. Nationally, the average cost for metal roofing installation ranges from $6,000 to $20,000. The wide price range represents different roof sizes, different types of metal, and the cost of labor in different parts of the country — and can also include the cost of removing an old shingle roof prior to installing the metal. As a line item, the average cost of removing an old roof to prepare for installing a new roof, plus adding new roof decking, costs on average about $45-$75 per square (the pro roofer’s term for 100 square feet), depending on the pitch of the roof. Always make sure you have a clearly written contract and a warranty on both the labor and the metal.
A standing seam metal roof may be a strong, durable, safe choice when you’re considering metal roofing installation options. A standing seam refers to the raised seam where the sheet metal roofing panels join. Traditionally, shingles and roof panels lie flush to the roof, making them more prone to rust or penetration by water at their seams. In a standing seam metal roof, the raised (or standing) seams run vertically from the roof ridge to the eaves, with no horizontal seams. In addition, the fasteners joining the metal panels together are concealed, providing even fewer opportunities for water or moisture to build up. The cost to install a standing seam metal roof will depend on the type of metal you select, the size of your roof, and the cost of roofing labor in your region. Materials will play a major role in your metal roofing installation costs. If you select standard galvanized steel, the cost per square (100 square feet) might be in the $150-$300 range, while a high-end choice such as copper or zinc could be between $1,000 and $1,500 per square. Here is one example of cost:
- Standing seam metal roof: $300 per square to start, including materials and labor.
- A 30-square roof could cost $9,000 or more.