Metal roofing
Buying surplus trapezoidal sheets: inspecting a batch before ordering
At a glance
When buying a surplus batch of trapezoidal sheet, first work out how many of the available sheets actually fit the building. List lengths, cover widths, profiles and coated faces. Separate sheets with bent edges from those that merely differ in shade. Bent edges may prevent a tight side lap, whereas a shade difference may matter mainly on a prominent elevation. Assess each sheet against its proposed position. A schedule of usable pieces gives a better basis for pricing the batch than its total area. For structural decking, you also need documentation identifying the exact profile and material.
What belongs in the batch inventory?
Group sheets by profile, length and exposed face. Match any T18 or T35 marking to a section drawing. If documents are missing, do not assign a cover width taken from a similar-looking sheet.
Which defects affect the lap?
Inspect the edge ribs along their full length. Crushing halfway along a side lap may be harder to accommodate than damage on an end already marked for cutting. Mark its position on the sheet sketch.
Laying two sheets together on a suitable support can reveal different rib spacing or incompatible lap directions. This trial checks the geometry. Final fixing and sealing must still follow the specified system.
Is the documentation sufficient for structural use?
If buying a deck to carry the insulation on an industrial roof, obtain the steel grade, thickness and load tables for the actual profile. Price and rib depth alone cannot establish its capacity. Have the proposed use checked against the design.
The side lap, fixing zone and span between supports serve different purposes. A damaged sheet should not be reassigned to structural use merely because the damage will be hidden by insulation.
How do you check shade and coating?
Compare sheets in daylight, all facing the same way. Different reflections from the ribs can look like a shade mismatch. Where the batch is identifiable, keep the label showing the colour and finish.
Check whether a mark is on the protective film, in the organic coating or part of deeper damage. A stain left by swarf and corrosion at a cut edge warrant different assessments. Review doubtful sheets with the supplier before pricing and allocating them.
How do you allocate mixed sheet lengths?
Allocate sheets to a specific wall or roof slope, starting with the longest required runs. Using a shorter sheet in a long run introduces another joint. The system must permit the joint and the design must provide for it.
Check on the drawing whether removing a damaged end leaves sufficient length and an edge that can be finished properly. Assign cutting and additional flashing costs to that sheet position.
What does each usable square metre cost?
Add the cost of the batch, delivery and any missing pieces. Divide by the area your allocated sheets will actually cover. If part of the batch goes unused, a low price per gross square metre may look quite different on that basis.
Use the agreed piece list at delivery as well as the batch designation. Mark sheets intended for cutting and separate them from full runs so that the installers can place them as planned.
7 branches. Materials closer to your project.
- SEROCK — Dzierżenin 34 E
- BŁONIE — ul. Sochaczewska 138A
- RADOM — ul. Grobickiego 8
- ŁÓDŹ — Natolin 8
- OLSZTYN — Barczewo, ul. Prosta 9
- WROCŁAW — ul. Jerzmanowska 10C
- GORZÓW WLKP. — ul. Zielona 33/34
