Survey and setting out

The first step is not carrying panels but measuring. Record support beam spacing, top level, straightness and flatness, and check that weld spatter, bolt heads, pipes and cable trays do not block the panel from seating.

Put the results on a plan and mark the actual size of every bay. Grating is rigid and will not absorb a support error; it turns into gaps, rocking and noise instead.

Set out from one fixed datum edge, place the first panel, then work outwards in both directions. The datum is usually the wall or handrail side, because the edge trim there is the hardest to adjust.

Keep panels flat in store once they arrive, with bearers close enough that nothing sags over a long void. Check batch and size again before installation, and do not force a distorted panel; flattening it during fixing only locks in stress.

Checking the supports

Level error at the top of the support beams is the main source of poor levelling. When beams sit at different heights the panel rocks, tightening builds in stress, and cracks appear over time.

Support width needs checking as well. Too little bearing on the beam means high local pressure; a common requirement is at least 40 millimetres on each side, according to the support condition in the manufacturer's load table.

Beam material and coating affect the fixing. Galvanized steel, concrete and stainless supports take different connectors, and concrete brings embedded items and the pull-out capacity of chemical anchors into play.

Where support spacing exceeds the allowable span, add supports rather than forcing a deeper panel; the relationship between span and load is set out under FRP grating support spacing

Panel orientation and layout

Molded grating has no strong axis, but joints should stay away from main traffic routes and concentrated loads. A joint left in the middle of a walkway takes repeated wheel and heel impact and cracks first.

Pultruded bearing bars must run across the supports so the load travels down the short span. Fitting them at 90 degrees cuts capacity sharply, and it is one of the most common site errors.

Colour batches belong in the layout too. Keep one batch to one area; mixing batches shows as a colour difference that becomes more obvious in sunlight.

Put openings over bearing bars where possible, away from panel edges and mid-span. A hole cuts fibre and reduces section, so it needs edge distance and local reinforcement.

Gaps and thermal movement

Leave a gap between the grating and walls, handrails and pipes; never wedge it tight. FRP expands more than steel, long panels move with temperature, and fixing both ends hard causes hogging or cracking.

Size the gap from panel length, installation temperature and maximum service temperature; a common rule is two to three millimetres per metre, following the manufacturer's data. Gaps should be even, not tight at one panel and wide at the next.

Control the joints between panels too. Too wide and material falls through or heels catch; too narrow and the panels crush each other when hot. A joint needs support beneath it, never an unsupported butt.

Levelling and shimming

Level by adjusting the supports first, not by stacking shims. If beam tops can be adjusted, adjust them; only where they cannot should stainless shims or purpose-made packers be used locally.

Shims go under the bearing bar, never in the middle of a mesh opening. They need enough area and should stay a few millimetres thick, because layered shims loosen, corrode and compress.

Shim material has to suit the environment. Carbon steel shims rust quickly when wet and the rust layer lifts the panel; stainless shims resist corrosion but still form a couple with aluminium supports, so an insulating pad may be needed.

Re-check after levelling. Run a straightedge and level along the walkway and across it, confirm there are no lifted corners or sudden slope changes, and that drainage falls the right way.

Fastening sequence

Fasten in sequence: from the centre of the panel outwards, or diagonally from one corner, so the grating settles onto the support instead of one end being crushed down while the other lifts.

Use the manufacturer's torque and a torque wrench, not feel. Too tight cracks the grating or crushes the washer, too loose works free under vibration, and the bolts in one panel should be tightened in two passes.

Fastener number and position come from the load table and wind load, with edges and corners usually closer. Grating on roofs and open platforms also has to resist uplift, so hold-down plates cannot be dropped.

For fastener selection and corrosion protection, see FRP grating fastener selection

Site cutting and edge sealing

Cut with a carbide or diamond blade at moderate speed and a steady feed, so the resin does not overheat and burn. Collect the dust rather than blowing it away.

Seal every cut. Brush the matching edge resin onto the cut face to encapsulate the severed fibres, let it cure, then install. Tight programmes tend to skip this step, and it is where furring, staining and cracking begin.

Cut openings with a hole saw or jigsaw and seal the edges the same way; for the detail, see FRP grating site fabrication

Edge trim and transitions

Edge trim decides both appearance and safety. Close the cut against a wall with a trim or banding board, and round off exposed edges so nobody is cut or pricked by fibre.

Handrail posts, kick plates and transition treads should go in with the grating. Grating first and handrail later usually means drilling extra holes through an edge that has already been sealed.

Transitions between levels need a ramp or a step, never an abrupt upstand. Where grating meets concrete or steel grating, add a transition support so the joint does not become a water trap or a loose edge.

Walk-through and handover

Check area by area: flat panels, even gaps, every bolt present, sealed edges, reinforced openings and clear drainage. Mark defects on the spot rather than leaving them for handover.

Then walk it. Follow the main walkway, ramps, stairs and platform edges and feel for movement, noise, lifted corners and slip. Many faults only show themselves underfoot.

The handover file should include the layout drawing, fastener schedule, sealing records, cut and opening positions and the manufacturer's instructions, because maintenance and later modifications depend on them.

Sort the findings: safety items fixed on the spot, appearance items given a deadline, and missing supplier parts logged separately. Walk the area again after the work is done, to confirm that adjustments have not damaged sealing or fastenings.

For the overall platform scheme and how handrails and ladders fit, see FRP grating work platform solutions