A hundred metres of roof sheeting: how much material is in the quote?

One hundred linear metres could mean twenty 5 m sheets. Their lengths add up to 100 m. To assess the order, you also need the width and roof layout. Twenty short runs cannot automatically replace ten long ones. End laps require their own detailing and an allowance for overlap.

Assume an overall width of 1.142 m and a cover width of 1.100 m. Twenty 5 m sheets give 114.2 m² gross but 110 m² of cover once their sides overlap. The 4.2 m² difference is used in the side laps and is unavailable as spare material.

The finished roof area can be smaller again. Allow for edge cuts, slope shape and any end laps. Adding the nominal cover of all sheets does not guarantee that they fit any roof of that area. Use a cutting plan to establish the actual requirement.

Assume a net rate of approximately €9.73 per unit, using the unrounded converted rate for the totals. Charged per linear metre, the 100 m order costs €973.24 net. Charged per square metre of cover, 110 m² costs €1,070.56 net. Based on gross sheet area, 114.2 m² costs €1,111.44 net.

The displayed unit price looks the same each time. Changing its unit changes the bill. This is a worked example. Ask the supplier to show quantity, unit, rate and line total so you can check the arithmetic directly.

Check the unit used for discounts too. A reduction per linear metre produces a different order saving from the same amount per square metre.

List each length separately, with sheet count and cover width alongside it. Mark which roof slope will receive each group. Sheets of similar lengths can easily be mixed up on delivery or when lifted onto the roof. Simple drawing references reduce that risk.

Check whether sheets run from eaves to ridge in one piece. Otherwise account for end laps and their supports. Shortening sheets simply to meet a target number of metres can leave them unsuitable for the structure. The shape and position of each run must suit the roof and its installation method.

Check delivered lengths group by group. Two swapped items can give the same total length yet fail to fit the intended slopes. A sheet schedule showing the location of each item makes this discrepancy visible.

Check flashings, fasteners, seals and transport separately. Unloading, lifting equipment and installation may also be extra. Quotations vary. Even if someone calls it a “complete roof”, establish in writing which items are included.

On a small order, fixed costs make up a larger share per square metre. For example, a delivery costing €139.03 on 100 m² adds about €1.39/m². If missing flashings require another journey, the discount on the sheets can quickly disappear.

Write out the billing unit and total value on the order confirmation. Check that all items use the same tax basis. Agree the profile, thickness, coating, colour and which face receives the finish. Equal quantities can still describe products for different applications.

Sign off the sheet schedule and drawing together before production. Compare the delivered packs with that document. It is easier to identify a missing sheet than to argue about “a hundred metres”. This matters especially for sheets made to agreed lengths.