When choosing composite grating, four questions do most of the work: where the grating will be used, what will pass over it, how far apart the supports beneath it are, and how slip-resistant the surface needs to be. In this article we go through these four questions in turn and, using the values from our own technical table, show which model stands out for each.
We manufacture eight moulded composite grating models: H25, H30, H38, H50 and H58 in 38×38 mesh; H50 in 50×50 mesh; and H30 and H38 as 19×19 mini mesh. The letter and number give the height of the grating in millimetres.
1. Define the environment
Composite grating does not rust and resists acids, alkalis and salt water. Treatment plants, the chemical and petrochemical industries, marinas, ports and shipyards are therefore its main areas of use. Because it is an electrical insulator and non-magnetic, it is also preferred in energy facilities, substations and rail systems.
In food and beverage plants, or on platforms with people passing underneath, look at the 19×19 mini mesh models if it matters that small objects do not fall through. Mini mesh has a 19×19 mm mesh on top and 38×38 mm below. In chemical environments we select the resin system for each project; just tell us which substances are present.
2. Clarify the use and the load
A maintenance walkway, a crowded platform, a stair tread and a drainage channel all mean different loads. At the same span, a walkway and a platform carrying heavy pedestrian loads may be one or two models apart. Over drainage channels, 50×50 H50 with its large open area (72%) stands out; if vehicles will cross, an assessment based on the EN 124 load classes (A15 to D400) is needed, and we carry this out for each project.
Stair treads and platform panels are also cut from moulded grating. So there is no need to look for a separate material for treads; you choose the height that suits the span from the same model family.
In facade and decorative applications the grating is not walked on, so the lightest model is usually sufficient. 38×38 H25 weighs approx. 12.5 kg/m²; 38×38 H58, at approx. 42 kg/m², is the heaviest model in the family.
3. Measure the support span
The support span is the gap between the two supports beneath the grating. It is the most decisive dimension in the selection, because the load that can be carried drops quickly as the span increases. The table below shows approximate point load values taken from our load table.
| Span (mm) | H25 | H30 | H38 | H50 |
|---|---|---|---|---|
| 450 | 450 | 750 | 1,500 | 5,950 |
| 600 | 255 | 425 | 875 | 3,325 |
| 750 | 150 | 270 | 550 | 2,100 |
| 900 | 105 | 190 | 380 | 1,475 |
| 1000 | 85 | 150 | 305 | 1,190 |
For example, at a 600 mm span 38×38 H25 is limited to approx. 255 kg, while H30 carries 425 kg and H38 875 kg. When the span increases to 900 mm, even H38 drops to approx. 380 kg. You can choose between closer support spacing and a taller model; we compare the two options together with their weight and cost. The values in the table are approximate; the final selection is calculated for each project.
4. Choose the surface and panel
The standard surface is concave and is sufficient for most walkways. In wet, oily or sloping areas a gritted surface provides extra slip resistance; on stair treads the anti-slip nosing is gritted. A smooth (sanded) surface is used for facade and decorative work, and a covered surface bonded to a flat plate where the top must be closed.
Our standard panel size is 1000×4040 mm. 38×38 H38 is also available in 1220×3660 and 1000×3000 mm, and 50×50 H50 in 1220×3660 mm. We produce black, grey, yellow, green and blue; other colours can be discussed on request.
The open area also varies by model: 68% for 38×38 H25, H30 and H38, 74% for H50 and H58, 72% for 50×50 H50, and 42% to 44% for the mini mesh models. The larger the open area, the more easily water, light and air pass through the grating; mini mesh gives up part of this area to retain small objects.
If you are not sure of the answers to the four questions, that is fine. Our Which grating is right for you? tool takes you to a starting model in four steps; you can carry the result straight over to the quote form.