PVC trim
PVC trim, which is made from cellular PVC sheet, has become a staple in modern construction due to its durability, low maintenance, and resistance to weathering.
However, like any material exposed to the elements, PVC trim board is subject to thermal expansion and contraction.
Understanding PVC Trim's Thermal Behavior
Vinyl-based products, including Cellular PVC Trim, are susceptible to expansion and contraction based on temperature fluctuations.
The general rule of thumb is that 18-foot runs of Expanded PVC trim can expand or contract by 1/16" to 1/8".
Thermal exposure is most significant with linear expansion, particularly in long such as fascia applications.
Combating Thermal Exposure
Proper installation is key to mitigating the effects of thermal exposure.
Each installation is unique, but a general rule is to use an adequate number of fasteners and the recommended adhesive to prevent movement.
Adhesion and Fastening
Stainless steel fasteners are the preferred choice, though hot-dipped galvanized options are also advised.
For trim boards, it's recommended to use 8-gauge or thicker fasteners.
Where feasible, 16-gauge or thicker fasteners are recommended for trim mouldings.
Whenever possible, opt for trim screws for enhanced stability.
Install a minimum of two fasteners every 16 inches, ensuring they penetrate at least 1 1/4 inches into the substrate.
At the ends of each run, fasteners should be spaced no more than 1 1/2 inches apart.
When using air tools, operate them at the lower pressure range as per the manufacturer's specifications.
Pre-drilling screw holes is advisable for optimal performance and durability.
Moveable Joints
Movable joints, often referred to as expansion and contraction joints, are designed to accommodate controlled movement where it is most likely to occur, such as between the ends of longer 16' to 18' runs.
These joints should be secured with glue and fastened 2 inches from the end of each board, rather than directly at the joint.
Conclusion
PVC trim does expand and contract with temperature changes, but with the right installation practices, you can manage these movements effectively.
By adhering to the best practices outlined above, you can ensure that your PVC trim remains stable and maintains its aesthetic appeal, regardless of the thermal challenges it may face.
Proper installation is not just about immediate results but also about the longevity and performance of your PVC trim in the long run.