Roof coating

Liquid coatings are a genuinely useful option for flat roofs and metal roofs that are ageing but structurally sound: the covering has weathered, joints are starting to open and there are small leaks, but the deck and structure are fine. A coating system applied over that roof forms a continuous waterproof membrane, usually reinforced with fleece at the joints and details, and it can extend the life of the roof by many years for far less than stripping and relaying. It is also the right answer for many metal roofs on sheds, garages, farm and commercial buildings, where rust and failed laps are the problem. But coating is not a cure for everything, and a lot of money is wasted coating roofs that should have been replaced. If the deck is soft, if water is trapped under the existing covering, if the insulation below is wet, or if the roof holds large ponds, a coating simply seals the problem in. So we survey first: moisture readings, a look at the deck, the laps and fixings on metal sheets, and whether water sits on the roof. Where the roof is suitable, preparation is everything: cleaning, treating moss and rust, repairing splits and blisters, priming, then reinforcing every joint, upstand and outlet before the full coat goes on at the thickness the manufacturer specifies.

Metal roofs and cut edges

On metal sheeting the first failures are usually at cut edges, laps and fixings. We treat the rust, seal the laps and cap or seal the fixings before coating, since those are where water gets under a coating that was simply rolled over the top.