AZEK

AZEK trim is solid cellular PVC cut to the same sizes as lumber trim, and it is the board to use anywhere wood trim rots. It does not absorb water, it is not bothered by contact with the ground or with masonry, and it does not need paint to protect it. On a Montana house that means the places snow piles up all winter: skirt boards, the bottoms of corner boards, window sills and the trim around a garage door.

AZEK invented the category. The company started as Compression Polymers, cut PVC sheet into boards sized like dimensional lumber, and launched the first PVC trim under the name TrimTech 500 before renaming it AZEK. AZEK Building Products is based in Scranton, Pennsylvania, manufactures in Pennsylvania, and later acquired TimberTech, which is the decking side of the same company. Since 2025, AZEK and TimberTech have been part of James Hardie.

What AZEK Board Is, and Why It Beats Wood Trim

Every AZEK board is the same material all the way through: white PVC with no knots, no warp and no twist, cut to consistent dimensions board after board. There is no grain to split and no end grain to wick water, which is where wood trim always fails first. It resists moisture, mold and insects, and that last one matters here, because carpenter ants and the flickers that drill for them are hard on wood trim in Montana.

It works like wood. You cut it, rout it and mill it with the saw blades and bits you already own, and it can be glued up, carved and even heat-bent for an arched window. The boards come in a matte white that needs no finish at all. With UV at elevation and the temperature swings here, painted wood trim peels first on the sunny and snowy sides and needs repainting every few years. AZEK trim left white never does.

AZEK 1x4 and 1x6 Trim Boards

The 1x boards are 3/4 inch thick, the same as wood trim, so they drop into an existing detail without shimming. The 1x4 measures 3/4 by 3-1/2 inches and the 1x6 measures 3/4 by 5-1/2 inches, and both come in 9-foot and 18-foot lengths. Use the 1x4 for window and door casing and the 1x6 for fascia, frieze and skirt boards, where a wider face covers the gap between the siding and the ground or the soffit.

The 18-foot length is the reason to plan ahead. It covers a lot of fascia and rake runs in one piece, and every joint you leave out is one less joint to glue, fasten and watch. The 9-footers carry easily and cover casing legs and short runs with less waste.

AZEK 5/4x4 and 5/4x6 Trim Boards

The 5/4 boards are a full 1 inch thick: 1 by 3-1/2 inches for the 5/4x4 and 1 by 5-1/2 inches for the 5/4x6, in the same 9-foot and 18-foot lengths. That extra quarter inch is what you want for corner boards and for casing that siding butts into. Lapped siding stacks up close to 3/4 inch at the butt, so a 1x corner ends up flush or buried. A 5/4 corner stands proud, gives the siding a clean edge to die into, and leaves a caulk joint you can actually tool.

If you are re-trimming a house that gets new siding, use 5/4 at the corners and around the openings and 1x for fascia and frieze. That combination gives every course of siding a clean edge to land on.

AZEK trim board	Actual size	Lengths	Best use
1x4	3/4 in. x 3-1/2 in.	9 ft and 18 ft	Window and door casing
1x6	3/4 in. x 5-1/2 in.	9 ft and 18 ft	Fascia, frieze and skirt boards
5/4x4	1 in. x 3-1/2 in.	9 ft and 18 ft	Corner boards, casing under lap siding
5/4x6	1 in. x 5-1/2 in.	9 ft and 18 ft	Wide corners, band boards, garage door trim

How to Install AZEK Trim

Fasten AZEK trim with stainless steel or hot-dipped galvanized fasteners long enough to go through the board and at least 1-1/2 inches into solid framing. For a 5/4 board over sheathing, that means a longer nail than you would reach for with wood. A standard nail gun works; set the pressure so the head sits just below the surface.

Never use brads, staples or wire nails. PVC moves with temperature along its length, and thin fasteners cannot hold it. That matters anywhere a Montana winter day starts below zero and ends in the sun, and most of all in Great Falls, where a chinook can swing the temperature fast. Fasten every board well and allow for that movement at the ends of long runs, and the joints stay tight.

Painting AZEK Trim

You do not have to paint AZEK, and most people don’t. If you want color, use a 100 percent acrylic latex paint with a light reflectance value of 55 or higher, which means light and mid-tone colors. Dark colors soak up heat, and heat is what moves PVC. AZEK also makes a PaintPro version with a surface made for paint, and prefinished colors, for jobs where a dark trim color is the plan.

To clean it, a hose or a soft cloth with mild detergent takes the dirt right off.

Why AZEK

Wood trim fails at the bottom: the last six inches of a corner board, the sill under a window, the skirt that sits in snow until April. AZEK does not absorb water, so those are exactly the places it earns its keep. You get the same sizes and the same tools as wood, no knots to cut around, no paint you have to keep up, and a Lifetime Limited Warranty from the company that invented PVC trim. Trim a house once with it and you are done trimming that house.

Frequently Asked Questions

Is AZEK PVC?

Yes. AZEK trim is cellular PVC, solid and white all the way through. It does not absorb water and resists mold and insects, which is why it outlasts wood trim near the ground and around windows.

What is AZEK board?

AZEK board is PVC trim board made in the same sizes as wood trim, such as 1x4, 1x6, 5/4x4 and 5/4x6. It cuts, routs and fastens with ordinary woodworking tools and needs no paint for protection. AZEK also makes mouldings in the same material, including brick mould, sill and drip cap profiles.

How do you install AZEK trim?

Use stainless steel or hot-dipped galvanized fasteners that go at least 1-1/2 inches into the framing behind the board, set just below the surface. A standard nail gun works. Do not use brads, staples or wire nails, because they are too thin to control the board’s expansion and contraction.

Does AZEK trim come in colors?

Standard AZEK trim is matte white. It can be painted, and AZEK also makes prefinished trim in multiple colors and a PaintPro trim made to take paint.

How do you paint AZEK PVC trim?

Clean the board and paint it with 100 percent acrylic latex paint in a color with a light reflectance value of 55 or higher. For darker colors, use PaintPro trim with a vinyl-safe paint.

Are TimberTech and AZEK the same company?

Yes. AZEK Building Products acquired TimberTech, and both have been part of James Hardie since 2025. TimberTech is the decking brand and AZEK Exteriors is the trim, moulding and siding brand.