Technology of Metal Roofing Installation

This material is manufactured in factory conditions, and high-quality powder coating protects the metal from corrosion for many years. In terms of strength and durability, this coating significantly surpasses similar materials based on asbestos cement (shingles).

From the installation standpoint, metal roofing is not the simplest roofing solution — it has its nuances, and cutting the material for complex, stepped roofs results in significant waste and offcuts. In this article, we discuss key installation details and provide a step-by-step guide to the process.

Preparation of the Base: Roof Sheathing

For making sheathing, you can use planed 25 x 100 mm boards or unplaned lumber. The spacing of the boards is chosen individually depending on the selected roofing tile’s profile. Typically, this spacing is around 400 mm.

The board extending to the eaves must be 10–15 mm thicker than the main sheathing, as this area bears higher loads from wind and snow. A critical step is installing a waterproofing layer under the sheathing. Never install the waterproof membrane directly on top of the boards, as ventilation of the roof space is often poorly designed and insufficient to fully and freely remove condensation. The sheathing also creates an air gap between the under-roof waterproofing and the installed metal roofing. The gap size equals the thickness of the board.

Installation of eave, ridge, and end flashing must follow these recommendations. The end board must exceed the sheathing thickness and align with the profile height of the metal roofing. For more secure fastening of the ridge beam, two additional boards are installed beneath it. The beam must be fastened with special care to ensure a secure hold, as it connects the panels of two roof slopes.

Eave flashing is typically made from the same material as the metal roofing. It is fastened every 300 mm using roofing nails. To ensure proper overlap, the flashing must extend at least 100 mm beyond the metal roofing.

Installation of Metal Roofing Panels

The sequence of installing metal roofing panels depends on the roof configuration. On a gabled roof, installation begins at either end (gable). On a four-pitched (i.e., pyramidal) roof, panels are laid from the highest point downward.

The overlap between adjacent panels must be arranged so that each subsequent panel covers the capillary groove of the previous one. Depending on the metal roofing model, this groove may be located on the leftmost wave or directly along the left edge. The first panel is installed with a 40 mm overhang beyond the eaves. Fastening is done into each wave.

If installation proceeds from left to right, each subsequent panel is inserted under the right edge of the previous one. This simplifies panel fastening. To ensure a straight installation line across the entire roof, it is recommended to initially secure three to four panels to a single screw, allowing them to move freely. Then adjust their position so they align with the eaves. After this, full installation of each panel can proceed.

Most metal roofing models are fastened to the sheathing using only self-tapping screws. However, some types (e.g., Kaskad) can also be secured using galvanized roofing nails. Roofing screws must always include a washer with a rubber seal. Importantly, avoid over-tightening the screw to prevent rubber seal damage and future leaks. Fastener consumption should be at least six units per square meter. Screws are driven into the wave’s depression on the metal roofing.