How and when should a metal roof be maintained?

Maintenance painting of a metal roof significantly extends the roof’s lifespan. Over time, soot, algae, and other dirt accumulate on a metal roof. If the roof is not cleaned periodically, stubborn dirt and wind-blown debris quickly wear down the protective coating on the metal roof. Keep these tips handy for maintaining your own metal roof.

When the coating wears down, it no longer effectively protects the roofing metal, exposing it to oxidation, which causes the roof to rust. To prevent this, the metal roof must be maintained and painted regularly.

Conduct an annual metal roof condition inspection

For a new roof under warranty, an inspection interval of five years is sufficient. After the warranty period, it’s advisable to check the roof’s overall condition annually.

During the condition inspection, first visually scan the roof’s overall appearance for any scratches, rust, and dents. After this, check the valleys to ensure water can flow through them unobstructed.

If no damage or significant dirt is found on the roof, removing loose debris from the valleys and rainwater systems is sufficient for maintenance.

Also check any screws with their seals and penetrations to ensure they are tight and not leaking water. The overall appearance of the paint surface or coating is assessed by examining the roof thoroughly from a viewing distance of about one and a half meters.

The paint surface is in good condition if the inspection reveals no visibly noticeable unusual color variations, flaking paint, or rust.

If no damage or significant dirt is found on the roof, removing loose debris from the valleys and rainwater systems is sufficient for maintenance.

Maintenance washing of a metal roof extends the coating’s lifespan

Washing and keeping clean are the most important aspects of metal roof maintenance. The less debris and algae on the coating, the slower it wears down.

Rainwater easily keeps a new or freshly painted metal roof clean from loose dirt and airborne impurities. However, as the coating ages, rainwater alone is no longer sufficient to keep the roof clean.

If the condition inspection has revealed stubborn dirt or algae on the roof, a maintenance wash should be performed on the metal roof. The wash is carried out using either a pressure washer or brush washing.

After brush washing, the roof must be thoroughly rinsed of cleaning agents, including the rainwater systems.

In maintenance washing, it is of utmost importance not to damage the metal and to avoid causing excessive stress to the paint surface. When washing with a pressure washer, note that excessive pressure can damage the paint surface, so the pressure must be set sufficiently low.

Brush washing, on the other hand, should be done with a sufficiently soft brush. When maintenance washing is done with a pressure washer, the roof usually gets clean enough without any special cleaning agents.

In brush washing, however, it is recommended to use a cleaning agent suitable for metal roofs. After brush washing, the roof must be thoroughly rinsed of cleaning agents, including the rainwater systems.

Snow removal from a metal roof protects the roof structure

During winter, snow accumulates on building roofs. An aged paint surface collects significantly more snow than a new or freshly painted roof. This is because as it wears, the paint surface becomes more porous, reducing its surface hardness and slipperiness.

For this reason, dirt and water don’t run off as easily. When frozen, water forms a good base for snow. When the snow load grows large enough, its weight begins to stress the roof structure and can, in the worst case, damage it.

Snow can also pose a danger to people moving near the roof. If snow has accumulated significantly, it’s advisable to remove it from the roof.

When planning snow removal, consider a few things.

First: Use appropriate, properly secured fall protection and safety equipment. Move on the roof with extreme caution, as thin sheet steel with certain profiles can easily be damaged when walking on the roof.

Third, it’s good to note that not all snow needs to or should be removed from the roof; it’s advisable to leave about a ten-centimeter insulating layer of snow on the roof. In terms of quality, the most important thing in snow removal is to avoid hitting the metal with the shovel or scraper, so the roof surface doesn’t get damaged.

Different metal roofs require different maintenance procedures

There are many different types of metal roofing that differ in thickness, composition, and profile. The most common metal roofs are various pre-finished thin sheet steels, standing seam metal roofing, and snap-lock panels that resemble standing seam metal.

Tile-profiled sheet metal and snap-lock roofing are modern, quick-to-install basic roofs that are usually factory pre-finished with PVC coatings. The manufacturer typically offers a warranty of about 10–20 years on the coating.

It’s important to note that PVC-coated roofs cannot be reliably maintenance painted.

Water-based metal roof paints do adhere to PVC coating without problems, but after painting, the original coating may detach from its substrate, and this is very difficult to predict. Therefore, it is especially important for these roofs to ensure regular and thorough cleaning so that the roof’s service life is maximized.

A standing seam metal roof can last up to a century if it is well maintained and maintenance painted every 10–15 years.

A standing seam metal roof, known as the most durable metal roof, is a metal roof seamed on-site from metal sheets. The material is most commonly hot-dip galvanized steel sheet. After installation, standing seam roofing must be allowed to oxidize for about two years before it can be painted.

If the roof is painted before it has had time to oxidize, the paint won’t adhere properly to its substrate and will soon need repainting. A standing seam metal roof can last up to a century if it is well maintained and maintenance painted every 10–15 years.

Metal roof maintenance painting protects the roofing material from corrosion

Metal roof maintenance painting is a good and cost-effective way to keep a standing seam metal roof beautiful and durable.

If it has been over 10 years since the last maintenance painting, or if the condition survey has revealed paint fading, chalking, flaking, or rust—maintenance painting is due. However, the best time for maintenance painting is before the old paint surface starts flaking. The most important function of the paint surface is to protect the roofing metal from wear and corrosion. Timely maintenance painting keeps the roofing material undamaged.

Before painting, it’s important to determine that the old coating can receive new paint. Additionally, the roof structure must be in good condition for painting to make sense.

Painting an old metal roof always begins with thorough cleaning of the roof. Washing should be done with a pressure washer, metal cleaning agent, and brush to ensure the washing result is adequate. Next, any rust spots are sanded away and the edges of flaking paint are gone over mechanically with a wire brush.

After this, all bare metal areas are primed. At this stage, the roofing metal has only well-adhered old paint and, in treated problem areas, one fresh paint layer. Carefully done preparatory work ensures a successful final result. Finally, the entire roof is painted in one or two coats with quality metal roof paint.

Maintenance saves you money

Due to varying weather conditions, a metal roof is subjected to extremely heavy stress here in Finland. The scorching summer sun, autumn rains, and winter snow loads are all factors that test both the metal roof and the roof structure. If completely neglected, a metal roof can reach the end of its life in as little as 20 years.

Regular maintenance, on the other hand, extends the roof’s service life by even decades, thus saving the homeowner real money. When you inspect and maintain your metal roof at regular intervals, you know your roof is in good condition and can peacefully listen to the patter of rain from the roof.