How to order tile-effect steel sheets for an uneven roof

A slope with a horizontal run of 4.80 m and a rise of 2.40 m has a geometric slope length of approximately 5.37 m. This right-triangle calculation excludes the overhang and the end details. To obtain the order length, allow for the chosen profile and how the sheet finishes at each end.

Measure both side edges, the width at the eaves and at the top, and both diagonals of each slope. Mark the endpoints of each measurement. Distortion or previous repairs may leave a trapezoidal outline or a corner out of line. Draw the shape the measurements show. Keep the initial survey as a record of the old roof and take final dimensions after repairs.

Check the straightness of the eaves and the plane of the supports. Correcting the frame before final measurement can save having to fit every sheet separately. Arrange safe access and fall protection for surveying the roof and taking measurements at height.

Locate each obstruction relative to fixed edges such as the eaves and verge. Record its width, its dimension along the slope and the space needed for flashings. Add a photograph to the dimensioned drawing. Include future penetrations once their positions are agreed, since moving one can change the sheet layout.

Give each field around a dormer or valley its own dimensions. On the cutting plan, mark which pieces need trimming and where an offcut could be reused. The profile and lap direction determine whether a cut piece will fit elsewhere.

Specify the exact profile, steel thickness, coating and colour. Include the cover width and the spacing of transverse steps. Even with made-to-measure sheets, the pressed pattern limits where a sheet can end. Check the available lengths and permitted end sections for that product.

Agree whether a dimension denotes the full sheet length or the length it covers. If a strip consists of two sheets, include the specified end lap. Check which allowances the cutting plan already includes. Counting a lap twice adds cost and can prevent the pattern from lining up.

Check the access road, unloading area, storage space and route onto the roof before choosing a length. Long sheets can twist during handling. Plan support along the transport route to protect their shape and coating. A narrow site can require different lifting arrangements from an open one.

Shorter sheets introduce additional end laps. Their position and dimensions must suit the profile and roof conditions. Agree the cutting plan with the installer before production, taking into account the sheet lengths the crew can safely lift and fit.

Request a schedule of quantities and lengths for each slope. Check laying direction, width of the last strip and the full set of flashings. Give the sheets simple reference marks on the drawing. These help the crew check deliveries and distinguish pieces for similar-looking parts of the roof.

Sign off once structural changes are complete. If the eaves moves or wall insulation is added after measurement, revisit the layout. On delivery, compare the sheets with the schedule and inspect the finish. Keep the approved drawing for future replacement or extension work.