The only answers from the manufacturers’ representatives was to nail it more or glue it. No warranty was available because the manufacturer always claims that there is some flaw in the installation of the product. The problem with these products is that they are unstable. The PVC Lumber expands in the summer and contracts in the winter.
The thinner the product installed, the more the thermal movement. A job done with perfect cuts and miters in the summer can have 3/8” gaps in the winter. A job done in the winter will “hoop” between nails in the summer. Our company has a 100% callback on PVC trim. Without support from the manufacturers and no answer to curing this problem, we don’t use these trim materials on home exterior jobs.
There is also a question as to the chalking of these products, even when painted. A couple of years after installation, the PVC Lumber often will chalk. This is just another reason we have moved away from the PVC’s.
Installers, experts and the general public are welcome to chime in here to comment.
I want to add a warning regarding the use of PVC trim boards under fiberglass cladding (that is fiberglass decking - fiberglass reinforced, polyester resin, etc.) as the thermal movement will cause cracking in the rigid fiberglass reinforced cladding.
Trim Boards made of primarily Fly Ash are more stable, cost less and handle and install better than PVC trim. For years we have had the problems with the PVC trim, primarily with the thermal movement and failures in the field. Painting was a challenge with special priming. The color of the paint had to be checked because too dark of a hue can cause the plastic substrate to warp. Our use of these products is over. We were using the PVC trim in cases where the trim was installed at grade or subject to moisture.
We now have at our disposal products that can be put down in moist areas and they will not rot. Bug won't eat the Fly Ash. Painting is a pleasure as any color works without priming. No special fastening is needed. No adjustments for thermal movement have to be considered. Truly we have now products that are better than wood. They are nonstructural boards that can be milled into crowns and casings, etc.
It is with great joy that we say goodbye to PVC trim!
by Bob Wewer