Technical Guides
Technical guides on choosing galvanized steel, coating classes, weight calculation and application tips.
Trapezoidal sheet is fixed with self-drilling roofing screws with EPDM washers, most often 6.3 mm in diameter. Screw length = purlin wall + sheet or panel thickness + at least 10 mm; sources usually recommend 5–8 screws per m². Roof pitch (%) = rise ÷ run × 100; the minimum pitch for trapezoidal sheet is usually given as 5–10% depending on the profile.
Black sheet is hot-rolled with its oxide scale; HRP is the same sheet pickled and oiled; DKP (cold-rolled) is pickled sheet rolled again at room temperature for tighter thickness and a smooth surface; galvanized sheet is coated with zinc for corrosion protection. Only galvanized sheet carries its own protection against rust.
Galvanized sheet can be painted, but paint applied as on bare steel will peel. Degrease, lightly abrade, use a primer made for zinc (epoxy, acrylic or wash primer) and a compatible topcoat; never apply alkyd (oil-based) paint directly. Zinc plus paint (a duplex system) lasts longer than both separately.
The life of galvanized sheet depends on the zinc thickness and the corrosivity of its environment. Z275 sheet carries about 19 µm of zinc per side; by ISO 9223 zinc loss rates this lasts roughly 9–28 years in a medium (C3) environment and longer in rural air. The often-quoted 10–70 years applies to thick batch galvanizing.
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.
A sandwich panel is two steel skins with a PIR, PUR, EPS or mineral wool core. Thicker panels insulate better; the effective width is typically 1000 mm and the length is cut per project.
Colours of pre-painted galvanized steel are specified with RAL codes. The most common standard colours are RAL 9002 grey white, 3009 oxide red, 5010 gentian blue, 6005 moss green and 7016 anthracite grey; other RAL colours are sourced on request.
The most common galvanized sheet sizes are 1000 × 2000, 1250 × 2500 and 1500 × 3000 mm. One square metre of Z275 galvanized sheet weighs 4.20 kg at 0.50 mm and 8.12 kg at 1 mm.
Prepainted steel sheet is a coloured steel plate obtained by baking galvanized coil with primer and topcoat in a coating line and then cutting it to the required size in the cut-to-length line. Ipek Metal supplies PPGI sheet in thicknesses of 0.30–1.20 mm, with Z100–Z275 substrate and in RAL colours.
Share thickness, coating and tonnage — we will get back to you with stock and pricing as soon as possible.