Moulded vs Pultruded GRP Grating: Which Should You Specify?
A practical guide for engineers, designers and specifiers
When specifying GRP grating, one of the first decisions an engineer or designer needs to make is whether to use moulded GRP grating or pultruded GRP grating.
Both types of glass reinforced plastic grating offer significant advantages over traditional steel grating, including corrosion resistance, low maintenance, high strength-to-weight ratio and excellent durability. However, their different manufacturing processes and reinforcement structures mean that they can perform differently depending on the application.
For designers and specifiers, selecting the correct type of GRP grating should therefore take account of factors such as span, loading, deflection, support arrangement, environment, mesh size and installation requirements.
Relinea has produced a new Moulded vs Pultruded GRP Grating: Which Should You Specify? guide to help engineers, contractors, architects and other construction professionals make an informed decision when selecting GRP grating.
Download the GRP Grating Specifier’s Guide
Our practical guide explains the key differences between moulded and pultruded GRP grating and provides a straightforward framework for selecting the appropriate solution.
The guide covers:
- The difference between moulded and pultruded GRP grating
- How the manufacturing process affects structural performance
- Multi-directional loading
- Long-span applications
- Heavy-duty GRP grating
- Load and deflection considerations
- Mesh size selection
- Slip resistance
- Corrosive and chemical environments
- Cutting and fabrication
- Water and wastewater applications
- Industrial walkways and access platforms
- What information to provide to a GRP grating supplier
- A practical moulded vs pultruded GRP grating decision matrix
Download the full guide to use as a reference when designing or specifying GRP grating for your next project.
Moulded GRP Grating vs Pultruded GRP Grating
Although both products are manufactured from glass reinforced plastic, their construction is different.
Moulded GRP grating incorporates glass reinforcement distributed through the grating panel in multiple directions. This makes moulded grating particularly suitable for applications where loads may be distributed across the panel in different directions.
Pultruded GRP grating incorporates continuous structural reinforcement predominantly in the longitudinal direction. This can make pultruded grating particularly effective where longer spans, higher loading or predominantly one-way loading are required.
Neither type is automatically the better option. The correct choice depends on the requirements of the individual application.
When should you specify moulded GRP grating?
Moulded GRP grating is commonly used for industrial walkways, access platforms, flooring, stair treads, trench covers and other applications where corrosion resistance, slip resistance and multi-directional load distribution are important.
It can be particularly suitable where:
- Loading may occur in more than one direction
- Standard panel sizes are appropriate
- Open mesh grating is required
- Corrosion resistance is important
- The grating will be used in wet or aggressive environments
- A wide range of mesh configurations is required
- Conventional industrial walkways or platforms are being designed
Relinea supplies moulded open mesh, mini mesh, solid top and pultruded GRP grating for a wide range of industrial and infrastructure applications.
When should you specify pultruded GRP grating?
Pultruded GRP grating can be particularly advantageous where structural performance and span are key considerations.
It may be appropriate for:
- Longer-span walkways
- Industrial access platforms
- Heavy-duty applications
- Areas subject to higher loading
- Applications with predominantly one-way loading
- Projects where reducing supporting steelwork is desirable
- Structural flooring applications
The continuous glass reinforcement used in pultruded products can provide increased stiffness and strength in the primary load-bearing direction.
As with any structural product, the actual span and loading capacity should be established using the manufacturer’s technical information for the specific product being specified.
Moulded vs Pultruded GRP Grating: Quick Comparison
| Requirement | Moulded GRP | Pultruded GRP |
| Multi-directional load distribution | Often preferred | Suitable depending on product |
| Longer spans | Suitable | Often preferred |
| Higher loading requirements | Suitable | Often preferred |
| Corrosive environments | Suitable | Suitable |
| Water & wastewater | Suitable | Suitable |
| Industrial walkways | Suitable | Suitable |
| Access platforms | Suitable | Suitable |
| Open mesh | Available | Available |
| One-way structural loading | Suitable | Often preferred |
| Lightweight installation | Yes | Yes |
Important: This table is intended as a general guide. Actual suitability depends on the specific product, span, loading, support arrangement, resin system and environmental conditions. Always refer to the manufacturer’s technical information and seek engineering advice where required.
What should engineers consider when specifying GRP grating?
Selecting moulded or pultruded grating is only one part of the specification process.
A suitable GRP grating specification should consider:
- Application
Establish exactly how the grating will be used.
For example:
- Industrial walkway
- Access platform
- Plant flooring
- Stair tread
- Trench cover
- Maintenance platform
- Rooftop access
- Water treatment access
- Span and support
The distance between supports is critical to the structural performance of the grating.
- Loading
Consider both uniformly distributed loading and point loading, as well as any equipment or maintenance loads.
- Mesh size
Standard open mesh may be suitable for many industrial applications, while smaller mesh configurations may be preferable where heel safety or small-object retention is important.
- Environment
Consider:
- Water
- Chemicals
- Saltwater
- UV exposure
- Temperature
- Industrial contaminants
- Cleaning chemicals
The appropriate resin system should be selected for the environment.
- Surface finish
Where personnel will walk on the grating, slip resistance is an important consideration, particularly in wet, oily or contaminated environments.
- Fabrication
Consider pipe penetrations, columns, equipment, access hatches and other cut-outs at the design stage.
Why specify GRP grating instead of steel?
GRP grating is increasingly being specified as an alternative to steel in environments where corrosion, weight, maintenance and slip resistance are important considerations.
GRP does not rust and can provide long-term performance in wet, chemical and marine environments. It is also significantly lighter than equivalent steel grating, which can simplify transportation, handling and installation.
Relinea supplies GRP grating throughout Northern Ireland, the Republic of Ireland and the UK, supporting contractors, engineers, architects and other construction professionals with product selection and technical guidance.
GRP Grating Supplier Northern Ireland, Ireland & UK
Relinea is a specialist GRP grating supplier in Northern Ireland, supplying GRP grating products for projects throughout Northern Ireland, Ireland and the UK.
Our GRP grating range includes:
- Moulded GRP open mesh grating
- GRP mini mesh grating
- GRP solid top grating
- Pultruded GRP grating
- GRP trench covers
Our products are used for industrial walkways, access platforms, plant flooring, stair treads, trench covers, water and wastewater facilities, utilities, rail, marine, data centres and other infrastructure applications.
Relinea also provides technical support, design, fabrication and installation services, allowing projects to be supported from initial specification through to delivery and installation.
Need Help Specifying GRP Grating?
Choosing between moulded and pultruded GRP grating can depend on the specific requirements of your project.
If you have a project requiring GRP grating in Northern Ireland, Ireland or the UK, our technical team can help you identify a suitable product based on the application, span, loading, environment and fabrication requirements.
Whether you are replacing existing steel grating, designing a new access platform or specifying GRP grating for a water, industrial, infrastructure or commercial project, we can provide technical guidance on the available options.
Talk to Relinea about your GRP grating requirements.
Call: +44 (0)28 9447 0010
Get a quotation or technical advice from our team.
About Relinea
Relinea is a specialist GRP company with more than 20 years’ experience in the design, fabrication, supply and installation of glass reinforced plastic solutions. We work with contractors, consultants, architects, local authorities and facilities managers across the UK, Ireland and Europe.
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