What does 100 m² of roofing sheet cost, and how does a linear metre differ?

A square metre describes an area. A linear metre means one metre of sheet length at a specified width. Without that width, prices cannot be compared. Price lists also distinguish between total square metres and effective square metres. The latter refer to the area covered after forming the overlap.

State whether you mean 100 m² of roof slope, 100 m² of sheet to be ordered or 100 linear metres of a particular profile. The supplier should not have to guess. Otherwise, you may receive a correct price for the wrong quantity. This is particularly important in telephone enquiries and short messages.

A linear metre of sheet is not a linear metre of eaves either. Roof sheets usually run down the slope. Their combined lengths can greatly exceed the building’s width. An itemised sheet list is therefore more useful for ordering than a general reference to “metres for the roof”.

Assume PLN 36.34 net per m² of cover for T18 trapezoidal sheet in 0.50 mm steel with a 25 µm polyester coating. Multiplying 100 × 36.34 gives PLN 3,634 net. With an assumed 23% VAT rate, this becomes PLN 4,469.82 gross. This calculation covers material only. The price and correct tax treatment of your own order must be established separately.

The assumed unit price has two decimal places. Final billing may depend on the calculation basis and rounding used in the quotation. Check the value of the complete sheet schedule before ordering. Simple multiplication is neither a finished invoice nor the price of a complete roof.

The sheet in this example covers a width of 1.10 m. A length of 100 linear metres therefore provides 110 m² of effective cover. At PLN 36.34, the cost is PLN 3,997.40 net. That is PLN 363.40 more than for 100 m². The difference comes solely from quantity, not a price increase.

The profile’s total width is 1.142 m, so 100 linear metres contain 114.2 m² of physical sheet area. Do not multiply this figure by a price per effective square metre. Area and rate must use the same billing basis. A small unit error can affect the entire estimate.

A 100 m² roof may require more material. Sheet layout and cutting determine the quantity. There is no fixed waste percentage for every roof: two rectangular slopes may produce a different result from a roof with valleys and dormers.

The order should specify lengths and quantities. Schedule each slope separately and agree on the eaves and ridge details. Include the overlap where end laps are needed. Do not add it twice if it is already included in sheet lengths. A drawing showing the actual layout is the easiest way to prevent this error.

For an illustrative slope measuring 10 m along the eaves and 5 m down the slope, ten strips are needed at a cover width of 1.10 m. Their total length is 50 linear metres. They provide 55 m² of cover, although the slope itself measures 50 m². This illustrates rounding up to whole strips and excludes eaves allowances and the ridge detail.

For a second example, assume T18 with a cover width of 1.128 m priced at PLN 41 net per linear metre. This is approximately PLN 36.35 per m² of cover. One hundred linear metres cover 112.8 m² and cost PLN 4,100 net. Convert the units before comparing offers. Never combine the width of one variant with the price of another.

This shows why the complete product name matters. T18 alone does not define cover width. Thickness, coating and suitability for roofing must also be confirmed. A common unit is the first step, but does not yet establish equivalent quality.

Add flashings, fasteners, seals and layers beneath the covering. Delivery and unloading also need prices. Installation requires a separate quotation with a defined scope. Area alone says nothing about chimney numbers, building height or access difficulties.

For a free quote, specify that you need the total value of the complete package for the attached plan. Ask for both total and effective areas, with net and gross amounts clearly shown. This reduces the risk of an apparently cheaper offer covering less material or using a different unit.

Also explain whether unloading will be manual or mechanical. With long sheets, this affects delivery planning. A price for 100 linear metres without the individual lengths does not fully describe the transport and handling requirements.

No. Area depends on sheet width. At a cover width of 1.10 m, 100 linear metres provide 110 m² of effective cover.

Orders use specific lengths and quantities. Their total may not equal exactly 100 m², particularly when tailored to a roof.