Trapezoidal steel sheets can quickly enclose a roof or facade once the supporting structure is ready. The sheets are lightweight, come in a range of profiles and go on dry. T18 and T35 are common starting points when comparing options. A single steel skin provides weather protection. Any thermal insulation has to be specified separately. Select the sheet to suit the design loads and support spacing, and include the fixings, seals and flashings in the order. Between its fixing points, the sheet carries its own weight and the loads allowed for in the design. Even when used only as external cladding, its strength needs to be checked against the actual support arrangement.

Trapezoidal steel sheets can cover a garage roof, clad its walls or screen the side of a carport. Choose the coating and details to complement the house, and allow for moisture, heating and any future extension. A garage used for parking or storing tools has different requirements from a small workshop. In unheated storage, the priorities are keeping rain out and letting moist air escape. In a workshop, temperature, daylight and noise also affect everyday use. Planning for these uses from the outset can save later alterations.

Trapezoidal steel sheeting can make a durable, low-maintenance garage roof and wall cladding if the sheets suit both the frame and the way you use the space. An unheated lock-up has different needs from a workshop. When comparing T18 and T35, look beyond colour and price: check the profile, coating, drainage and how you will manage condensation. A parked car brings rainwater indoors. As it evaporates, humidity rises unless air can circulate. This matters even in an unheated garage, where metal roofing can cool down sharply at night.