Contractor Handbook - Expansion and Contraction

  • PVC movement occurs due to temperature flucuations.
  • This movement is restricted to the length of the product.
  • The product will not swell or shrink like wood experiencing a moisture cycle.
  • Expansion and contraction is ONLY an issue on longer “runs” (rake, fascia, frieze) comprised of multiple pieces (3 or more) 18’ boards (short lenghts, around windows for example, can and should be built with tight joints).
  • The more the product is mechanically fastened or bonded on longer runs, the less likely it is to move.
  • Screws provide better holding power than nails.
  • As a rule, if you can bend the fastener in your fingers it is too thin (no wire or brad nails). 18 galv. and 16 galv. trim nails are not recommended.
  • Southern exposure, or areas where product is in direct sunlight, can result in greater movement. More fasteners should be used in combination with expansion joints.
  • All joints in high traffic or visible areas should be glued tight. Expansion/ contraction joints should be placed in inconspicuous areas along the run of trim.
  • Install long runs when boards and outside temperature are approximately 60-65°F. If practical, install long runs in the morning when it is still cool out and not in the middle of the afternoon.
  • Shiplap joints offer a superior joint, especially on long runs.

Method #1: Glue the Joints Secure (High Traffic Areas)

  • Shiplap the boards at the joint, and glue the boards together with VERSATEX Weld-on #705 or another acceptable PVC cement.
  • When possible, apply construction adhesive to back side of boards. Liquid Nail Sub Floor Adhesives or Heavy Duty Construction adhesive works well when attaching a VERSATEX fascia board to a sub fascia.
  • Double fasten on both sides of joint (remember: screws work best). Use proper amount of fasteners based on width.
  • If necessary, allow for movement at the ends of the boards or at inconspicuous joints.

Method #1: Click below to view drawing

Method #2: Leaving an Expansion Joint

  • Based on temperature at time of installation, create a gap between boards. (usually 1/8”)
  • Follow proper fastening methods previously outlined.
  • Place UV-resistant acrylic-based or polymer-based sealant in joint between boards (NPC Solar Seal #900 or equal is recommended).
  • Never completely fill joint with sealant. Leave room to compensate for joint closure.