Dimensional Properties of Southern Pine Particleboard Underlayment


  • Warren S. Thompson


The dimensional changes in particleboard underlayment installed over plywood sub-flooring on floor sections and exposed to different environmental conditions were investigated.

Gap formation between pairs of 8-ft particleboard panels attached by nailing occurred rapidly under drying conditions, causing print-through on narrow strips of vinyl floor coverings and rupture in the less elastic types. Attachment by glue nailing limited gap formation and prevented development of defects in floor coverings. Hot-melt coatings were effective in stabilizing particleboard panels of certain types when floor sections were exposed at 80 F and 10% relative humidity, but were of limited value when exposure was at 120 F and 20% relative humidity.

Changes in the distance from the joint between particleboard panels and points that were initially 1, 2, 3,—6 ft from the joint varied with the method of attachment of the panels to floor sections and were frequently in the opposite direction from that which occurs in unrestrained panels. The magnitude of the change and the direction of movement are explained in terms of the concurrent dimensional changes in the particleboard and the plywood subfloor to which it was attached.


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