Installing PVC Trim

By Robert Robillard on Home Repairs And Remodeling

Installing PVC Trim

Photo: Mudroom addition.

Installation Note: All trim in the article, Installing PVC Trim, is Azek PVC trim.  All miters were glued ~ Expansion joints are located on the inside [house] butt ends and under cover of overlapped boards and concealed with flexible caulking.

PVC Trim – What You Need To Know

Many customers these days are requesting that I use a PVC product to replace rotting wood. In these cases I recommend and use Azek trim boards.

My local lumber yard, Concord Lumber, stocks most of the sized I need and I glue up and make any specialty moldings or sizes that they don’t stock.

Azek is a great wood replacement choice non-stress application. The beauty of this product is that it cuts, drills, routs and fastens the same as wood.

However, there are a few considerations and procedures that should be followed when installing pvc trim to allow a quality installation. Many contractors are not aware or do not follow these steps.


1. Do not use finish, brads or staples.  Fasteners MUST have a head.

2. Fasteners should penetrate the wood substrate a minimum of 1-1/2”.
3.  The best fasteners I’ve seen are the Cortex [concealed fastening system] and are made by Fasten Master. This system has a special screw adapter that sinks the screw at the correct depth to receive a PVC plug. It’s real nice system and conceals the fastener heads without caulking, sanding or painting.
4. Install fasteners no more than 2” from the end of boards.
5. Install 2 fasteners for boards less than 12” wide. Wider boards require more fasteners.
6. Install fasteners every 12” to 16” o.c.


1. Glue joints and secure with a fastener to prevent joint separation.

2. Use AZEK adhesive – it has a 10 minute working time and is fully cured in 24 hours.

Expansion and Contraction

Here is where many contractors fail to follow the installation rules.   There is nothing worse than getting a call back a year later because trim boards open up 1/4″
1. AZEK does expand with temperature extremes and moves differently than wood.
2. A general rule of thumb is that AZEK will move 1/8” per 18’.
3. When installing long sections, such as 100’ fascias, consider using a solid sub fascia and construction adhesive and fasteners to reduce movement.
4. Installing and gluing one joint tight and allowing 1/16” on the other joint to move is another option. This joint can be ship lapped to hide the movement or cut as a scarf joint and then caulked with a flexible caulk.


1. AZEK does not require paint but using a 100% acrylic latex paint with Light Reflective Value [LRV] of 55 of higher will help reduce movement.

2. Darker color paints should have a Vinyl safe coating.

3. AZEK cleans up nicely with denatured alcohol.

If you enjoyed this post, please consider commenting or subscribing to receive my future posts via email

If you enjoyed this post, make sure you subscribe to my RSS feed!

About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

All posts by Robert »

Not what you're looking for?

Search for more articles here. Enter keywords like roof leak, bookcase, deck, etc to find your topic.

© Copyright 2019 A Concord Carpenter · All Rights Reserved