For most industrial walkways, open mesh GRP grating is the obvious specification. Free drainage, light transmission and natural ventilation all work in the building’s favour, and the grit top surface handles foot traffic safely. But there are projects where an open surface is the wrong answer. Cables drop through. Tools become falling hazards. Liquids drip onto operators below. In those situations, GRP covered top grating gives you the structural strength and chemical resistance of standard GRP with a sealed walking surface and zero penetrations.
What GRP covered top grating actually is
Covered top grating starts as a standard moulded GRP panel, then has a solid GRP plate moulded over the top to close the open area. The result is a single-piece composite with the same load characteristics as the underlying mesh, plus a continuous walkable surface. The top surface is finished with a grit anti-slip layer or a chequered profile, depending on the application. Panels are available in 25mm, 30mm and 38mm depths, in the same colours and resin systems as standard GRP.
Critically, the panel still flexes and behaves like GRP, not steel plate. Load ratings come from the underlying mesh structure, not the cover layer.
When covered top is the right call
Cable management and service risers
Covered top excels above cable trays, busbar runs and pipework. There is no risk of dropped fasteners shorting live services, and the panel itself is electrically insulating. It also doubles as a walkable inspection cover, which removes the need for separate plate covers fixed over the trays.
Mezzanines and overhead walkways
Anywhere people work directly below an access route, covered top removes the foreign object debris (FOD) risk. This is standard practice in aerospace and automotive assembly halls, and increasingly common in food and pharmaceutical environments where any drop from a walkway is a contamination event.
Public realm and visitor-facing platforms
Open mesh on a bridge or platform over a watercourse, tank or open void is structurally fine but reads as visually exposed. Members of the public regularly refuse to cross. Covered top resolves this with no compromise on slip resistance and no change in load class. Cleaner aesthetics make it the right choice for visitor centres, viewing platforms and public access routes at industrial sites.
Chemical dosing rooms and pump stations
Where the cleaning regime relies on capturing splashes and washing them to a single drain, an open mesh surface defeats the strategy. Covered top contains the spill on the panel and channels it to where the bund or drainage gulley is.
Where covered top is the wrong choice
- High water flow walkways where free drainage is the whole point, such as wash-down areas, drying floors and tank rim platforms.
- Routes where natural daylight transmission matters, for example mezzanines in light-starved warehouses.
- High-condensation environments where pooling on the sealed surface could become a slip risk faster than free drainage would shed it.
Mixing covered top with standard GRP
A common and economical specification is covered top only where it is needed, with standard mesh GRP elsewhere on the same level. Specify both at the same panel depth so the walking surface stays flush. Use M clips at panel edges and fishplates between panels to keep the transition clean. This approach controls cost without compromising the design intent.
Specifying covered top with confidence
- Match the load class to the actual loading, not a default. Refer to the load deflection tables for the specific panel depth.
- Confirm chemical resistance against the cleaning chemicals and any process chemicals the panel will encounter.
- Specify the slip rating to BS 7976. R12 is standard, R13 is available where the risk register requires it.
- Add hi-vis nosings on platform edges and stair tops to improve visual cue at thresholds.
- Confirm fire rating against the room use. Class 1 surface spread of flame is appropriate for most production environments.
Buy GRP covered top grating from Grating Direct
Grating Direct holds covered top GRP grating in stock alongside the wider standard and mini mesh range. Sample packs are available for in-house specification reviews, and cut-to-size service handles complex platforms and service riser layouts. For pricing on a specific project, send through your plans and the bespoke quotation team will turn around a costed proposal.
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