In short
Trapezoidal sheet profiles are named by rib height and rib pitch (e.g. 27/200). Roofing sheets are typically 0.40–0.70 mm thick and are cut to the required length; 3, 4 and 6 m are common.
How to read a trapezoidal profile
Trapezoidal profiles are usually named with two numbers: the rib height and the distance between ribs, both in millimetres. In a 27/200 profile, for example, the rib height is 27 mm and the rib pitch 200 mm. Higher ribs increase bending strength and allow wider purlin spacing.
Developed width and effective width
Trapezoidal sheet is roll-formed from flat sheet. The width of that flat sheet is the developed width; the width a panel covers after overlap is the effective width. The effective width is always smaller and depends on the profile. The number of panels for a roof is calculated from the effective width.
Thickness
Trapezoidal sheets for roofs and walls are typically 0.40–0.70 mm thick. Thicker panels are stronger and heavier. Use the trapezoidal sheet weight calculator for weight per metre and per m².
Length
Trapezoidal sheet is cut to the required length in one piece. 3, 4 and 6 metres are among the most requested lengths. A single panel from ridge to eaves avoids end laps; transport and installation set the upper limit.
How many trapezoidal sheets does a roof need?
The number of panels is based on the effective width: Panels = Roof width ÷ Effective width (rounded up). Example: a roof slope 12 m wide along the eaves needs 12 panels with a 1 m effective width. Panel length is the slope length from ridge to eaves plus the eaves overhang. Use the trapezoidal sheet weight calculator for total weight.
Installation
Panels are laid with side laps starting from the side opposite the prevailing wind and fixed to the purlins with self-drilling screws with EPDM washers. For screw type, length, quantity and roof pitch see the trapezoidal sheet screws and roof pitch guide.
Trapezoidal sheet or sandwich panel?
Trapezoidal sheet is a single skin: light, economical and quick to install, but it does not insulate and condensation can form on the inner surface in cold weather. A sandwich panel has an insulating core between two skins and is used in heated or cooled buildings. Trapezoidal sheet suits unheated stores, canopies and agricultural buildings; sandwich panel suits heated buildings.
Galvanized or pre-painted?
Galvanized trapezoidal sheet is economical and common on agricultural, storage and temporary buildings. Pre-painted trapezoidal sheet adds colour and extra protection with its factory paint over zinc; see pre-painted steel colours. Where insulation is needed, choose a sandwich panel.
Trapezoidal sheet prices
The price of trapezoidal sheet depends on sheet thickness, galvanized or pre-painted finish, profile type, panel length and total area. Because steel and raw material prices change frequently, we do not publish a price list; current prices are given as a quote.
Request a quote for trapezoidal sheet: just send us the thickness, finish (colour), profile, length and quantity or roof area.
This article was prepared by the İpek Metal technical team. Contact us for values specific to your project.