Project Overview

The Project – Void Formers

We like to show what polystyrene can do, particularly when a client might never have considered it. Increasingly popular within the construction and civil engineering industry polystyrene’s versatility has no limit. Therefore, polystyrene is the ideal solution for void formers and refractory linings. Precisely cutting polystyrene using CNC machinery means any size or shape required is achievable. As well as this whilst pouring concrete around it polystyrene is robust enough to hold the weight. Removing polystyrene from concrete is easy by either melting away with a solvent or burning away to leave the required void.

At Molygran we turn your problem into our solution. 

For More Information – Contact Us


DEH drop chute
Void Former


  • Polystyrene is a versatile material for void forming systems
  • Polystyrene is durable enough to withstand the weight of the concrete
  • Polystyrene can be cut to match any shape required for refractory linings
  • Polystyrene is the most cost effective material
  • Molygran have extremely quick turnaround times
  • Molygran will assist in ensuring the best possible solutions for our most complex designs

The brief The brief

Our client needed to apply a concrete refractory lining to the inside of steel ducting that would carry gases at extremely high temperatures at a power plant. Our solution had to be easy, quick to apply and right first time, as shutting down the plant cost thousands of pounds per day.

Void formers were required to create a space for instrument openings while the concrete was poured around it to form the lining. Precision was key but the formers also had to be easy to handle, install and dispose of when the concrete had set. Cost was also a factor as each polystyrene former could only be used once.

The solution The solution

Molygran used CAD drawings supplied by the client to design and create the void formers. We ensured the correct polystyrene specification was used and took particular care where there was a bend in the pipework.

As a result:

> the client was able to save both time and money with our solution
> design time was reduced by using data transfer and upload of technical drawings
> the void formers were produced 100% off-site which minimised on-site time, travel costs and plant/site closure costs
> the lightweight polystyrene formers could be easily moved around site by one person
> the polystyrene formers provided an improved finish, removing/minimising the need to re-work the surface of the inner concrete liner

Our construction client was pleased with our work and delighted by our response time. They were in a hurry to create the refractory linings and expected it would take a week to process their order. Molygran delivered the void formers within two days, described by the clients as “truly exceptional”.

They described the cost as “very reasonable”, an important factor as formers are usually burnt off or thrown away after first use.

As the client stated: “Molygran always come up with solutions that satisfy our needs. We have now used them for a number of years and we can rely on them 100%.”