November 30, 2021

FRP Grating: Molded and Pultruded Grating

To understand the difference between molded and pultruded grating, it is important to know exactly what fiberglass reinforced plastic (FRP) is. FRP is an alternative to traditional industrial materials such as steel, concrete and wood. It is made from a resin combined with glass fibers. Resin formulations, resin ratios and manufacturing techniques allow the product to be used as grating, handrails, ladders, decking and custom engineered solutions.

WEITONG wants to help people make the right decision when choosing the right material for their next project. Allow us to explain the differences between the two types of FRP grating.

FRP Grating: Molded and Pultruded Grating


The manufacturing process for molded gratings involves applying interlaced layers of liquid resin and long continuous glass fiber bundles in an open mold until the desired grating thickness is achieved. Once this has occurred, the panels need to be cured. The interwoven square grid structure will provide bi-directional strength to the product, meaning that the panel will be able to withstand the same load no matter which direction the load on top of the grating moves.

Pultruded gratings consist of more glass than resin. This type of grating is created by a series of parallel load bars that are kept parallel by a series of cross bars. These rods are made by pulling glass fiber roving through a pultrusion molding machine. The glass fibers then receive a resin bath and are wrapped with surface yarns made from bundles of glass fibers. These surface yarns reinforce the bars. Once the bars are prepared, they are assembled and turned into pultruded grids. Pultruded gratings have unidirectional strength, making them ideal for high load requirements or large span applications. 


The surface is a big difference. Molded and pultruded gratings are available in a variety of surfaces to best meet the requirements of the application and create a safe environment. Available surface options include

Curved Moon Top: The concave side of the curved moon top grating provides an excellent non-slip base in most environments. Half-moon tops are not suitable for barefoot passage.

Monolithic Applied Grit Top: This optional grit top grating has quartz sand that is monolithically applied, cured and sealed to the surface to provide an excellent non-slip base.

Aluminum oxide grit: This surface is extremely durable and provides a firm foothold for maximum safety.

Smooth: This grating surface has been sanded to create a smooth surface.

Molded gratings - Molded gratings offer more surface options than pultruded gratings. The top of this grating can be a square or rectangular grid.

Pultruded Grating - Pultruded grating offers three types of surfaces: monolithic applied grit tops, aluminum oxide grit, and aqua grit.


FRP Grating: Molded and Pultruded Grating

Which to choose

Both molded and pultruded grating have sufficiently strong grating configurations. Molded grating has a higher resin concentration, making the panels more flexible and impact resistant than pultruded grating. Glass reinforcement provides structural strength to both gratings. Pultruded grating has a higher concentration of glass fibers, making it a stronger grating.

Note that molded gratings are a better solution for shorter span applications, while pultruded gratings are a better solution for longer span applications. WEITONG can help you decide which type of grating is better for your next project.


Remember, both molded and pultruded gratings offer amazing advantages, and depending on the application, one may be more beneficial than the other. Remember, our experts are ready to help you with your questions, so send us an email and get a specific quote.