How to get the most out of a metal roof

When a building owner buys a metal roof, he expects a low-maintenance roof that can last many decades. However, ‘low-maintenance’ is not the same thing as ‘no maintenance.’ A wise contractor will advise the owner about simple things to do (and not to do) to keep the roof performing up to it’s full potential.

1. Keep It Clean – Leaves or other debris that do not get washed away by rain or snow should not be allowed to accumulate.  (Pine needles, for example, are particularly acidic). Cleaning from off-roof – with a long-handled brush like a window-cleaning brush, for example – is preferable to walking on the roof, if possible. (If you have to walk the roof, see tip #5.) 
2. Avoid Spraying Water Up Under The Roof – Roofs are made to shed water that is traveling downwards, not upwards. Asking your roof to do otherwise is just asking for trouble. If you use a hose, use it from above.
3. Clean the Gutters, Too – accumulations of wet leaves and debris right against the roof edge may inhibit the roof from drying out. The roof is designed to shed water, and then dry. If it cannot dry, corrosion may take hold.
4. Protect The Finish – The finish on the metal is integral to preventing corrosion. Scratches can compromise that protection, especially if metal is exposed. Foot traffic can scratch the finish with grit embedded in the bottoms of shoes. Overhanging tree branches can also scratch it if they sway low enough during windy conditions. (Hard, heavy branches may damage even more than the finish). Avoid unnecessary foot traffic, and consider brushing off the soles of shoes before stepping on the roof.  Do not slide heavy or rough objects on the roof. Trim nearby trees so they cannot contact the metal.
5. If You Must Walk On the Roof – When roof traffic is required, either to maintain it or to access some other system mounted on it, be careful. Follow the manufacturer’s recommendations for traffic. Avoid scratching the finish (see tip #4).  Step only on top of beams or purlins, and do not set down heavy objects on the roof between these supports.  Weight in between can create depressions that do not shed water or snow properly. And of course, take appropriate safety steps to protect the people on the roof!
6. Avoid Penetrations – Any penetration of the weather-protective skin of the roof is a potential leak site. Even if is it sealed afterwards, there is an increased risk of leakage. If something needs to be mounted on the roof, explore non-penetrating option for securing it. (Mountings on standing seam roofs, for example, can often be accomplished by clamping to the seam)

Use common sense to protect the roof from damage and keep it clean, and it will last long and perform well.