Choosing tile-effect metal roofing: four checks before you order

Prepare a roof plan with slope lengths, pitches and penetrations. Mark valleys, chimneys and roof windows. For a refurbishment, include an assessment of the existing supports and roof layers. The house floor area alone gives too little information to calculate the covering and its accessories.

Agree who will measure the roof on site and produce the sheet schedule. Differences between the drawing and the building affect cut lengths. Comparing schedules against one measured plan also reveals whether a lower quotation leaves out part of a slope.

Check the pitch and support requirements for the exact model. One modular system in the example documentation allows a pitch of 9°. Use that figure only for the specified system and under the conditions in its instructions. Look up the permitted pitch separately for each alternative.

Consider how many repeats of the tile pattern will be visible on the slope. A large pattern looks different on a small dormer than on a broad roof. View a sample alongside photographs of completed roofs, then confirm that the product is approved for your detail.

Ask for the steel thickness, steel grade, metallic coating and organic finish. Check each against the second quotation. A matt finish describes the surface appearance. Its corrosion resistance depends on the specific coating system.

Select the finish for exposure at the site. Read the provisions on corrosion, colour retention and maintenance. Perforation and colour warranties may cover different periods and defects. Check any location-specific exclusions before relying on an advertised warranty period.

On a simple slope, cut-to-length sheets can reduce end laps. Confirm access for the delivery vehicle and how the sheets will be lifted without bending. The longest sheet on the drawing must also fit the handling route on site.

Small modules can be easier to position on broken slopes and in tight spaces. The saving depends on the cutting pattern, lap direction and which offcuts can be reused. Ask for a sheet layout based on your roof geometry.

Use the price per square metre of effective cover after overlaps. A price based on the full sheet area uses a larger denominator and can look lower. Add the cutting allowance, flashings, fixings and components for roof penetrations.

Include transport, unloading and installation. Check the ventilation details, snow retention and roof access specified in the design. Ask whether matching replacement pieces and accessories will be available within the same system.

The written schedule should state sizes, quantities, steel thickness, coating and colour. For modules, include the count and effective area of one piece. For cut sheets, check each length. Agree the delivery date and how to report transport damage.

Assign purchasing responsibility for each component. A missing special flashing can hold up the crew even when all sheets are on site. Give the supplier and contractor the same approved materials list to avoid duplicate orders and missing accessories.

Place the order once the covering fits the measured roof, the material is specified and the installer has checked the model’s instructions. If delivery precedes installation, prepare suitable storage and provide for inspection of packs that arrive damp.

With the installation and quantities settled, compare the shortlisted colours and textures in daylight. You can then see what each price difference buys and whether that feature will make a difference on your own roof.