There are two methods of producing recycled plastic lumber: by pushing molten plastic out of moulds (extrusion) or by allowing it to form within the mould (intrusion). The British Recycled Plastic range of recycled plastic lumber is manufactured using the intrusion method. This produces much stronger profiles that will not warp, and are more suitable for construction purposes.

The major benefit of using extrusion moulding is that profiles can be manufactured to any length, whereas the length of intruded profiles is defined by the mould.

Therefore, comparing extruded and intruded recycled plastic lumber is like comparing apples and oranges, with extruded profiles far more flexible, and unsuitable for use as load bearers and applications where rigidity is key.