Skip to content


Q: How are recycled plastic lumber and other products manufactured and is there more then one process used?
A: Recycled plastic lumber and other of our plastic products are manufactured using two primary processes. One is called continuous extrusion and the other flow molding. Although both use an extruder in the first stages of the process, from that point on they are different.

Continuous extrusion is a linear process, whereby the softened plastic exits the extruder moving through a forming tool creating the desired board shape (2×4, 2×6,etc) or a, contoured bleacher seat. The plastic is pulled very slowly down a line sixty or more feet in length periodically sprayed with water cooling as it moves. At a specific point, the plastic is automatically cut into the required board lengths and stacked to finish cooling. The benefit of this process (although limited to linear shapes), is board lengths can exceed 30-40’ feet.

Flow molding is a process not limited to linear shapes whereby the material exits the extruder flowing into an enclosed mold – a wall mount bracket, mall end or, desired board shape. The mold, when filled is then moved allowing the product to cool and harden. Once that’s done the finished product is rremoved from the mold and the process starts all over again. The benefit of this process being that any number of product shapes and board sizes can be manufactured. Board lengths are limited to 8 feet.

Q: What kind of recycled plastic is used to make PMI plastic lumber products and how is it processed?
A: The plastic we use, is High Density Polyethylene (also called number 2 plastic) and is derived from 100% recycled post consumer bottle waste such as milk and juice containers.

The material is ground into flakes then pre-washed and cleaned in a decontamination process to a high purity level. This removes contaminants such as food residue, paper, metal, adhesives and dirt.

The material is then compounded into a rigid board stock material with the resulting finished product containing over 90% recycled post-consumer waste by weight.

Q: Can PMI plastic lumber products absorb moisture, be damaged by rot, insects or salt water?
A: No! Because our products are made with a single purified polymer, it is manufactured to exacting reproducible specifications and will not absorb moisture. It has exceptional resistance to corrosive substances, insects, salt water and other environmental stresses.

In addition, because it doesn’t absorb moisture, it will not rot, splinter, crack or peel and does not require water proofing, staining, painting or similar maintenance when used outdoors.

Q: Will PMI recycled plastic lumber products discolor or fade?
A: No! Because PMI products are made using the best colorants and UV. stabilizers technology has to offer, they have excellent weathering resistance and will not discolor (see warranty in the catalog section).

With regard to fading; Over the life of the product, Prolonged exposure to the environment will cause the color to soften, losing its shiny appearance. Power washing will serve to exfoliate the outer skin of the plastic, removing surface dirt, etc. and bring out the vibrancy of the color.

Q: What are the limits of plastic lumber products compared to wood?
A: Our standard Plastic lumber products have less rigidity and a lower modulus of elasticity ( beam strength ) then wood. However, applying the appropriate engineering and established ASTM standards for using plastic lumber, all PMI products and related system installations have been and continue to be, designed to address, comply with and if possible exceed the required specifications for the application.

Note: As a point of information, PMI does offer a line of structurally reinforced recycled plastic lumber products for use in structural applications.

Q: Are PMI recycled plastic lumber products harder to work with than wood and do I need special tools?
A: No! In many instances our plastic products are easier to work with. PMI products can be fabricated and installed using standard wood working tools. Plastic will drill and cut evenly and, since there is no grain, will not split. In addition, tests have shown our products will actually hold fasteners better than wood.

Back To Top