Azek Island Post Cap (4x4, 5x5, 6x6)

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Post Size: 3-1/2"
Sale price$28.00 Regular price$32.92


The Azek Island Post Cap is available in sizes to fit a variety of 4x4, 5x5, and 6x6 posts.  Made of polymer PVC that resists scratches, stains, mildew and moisture damage. The Azek Island is a popular style offering a layered flat top design with squared edges. Slips over the top of your post for easy DIY installation.

The Azek Island post cap is fabricated to fit a variety of post and post sleeves measuring 3.5” to 6.5” square. See actual product dimensions below.

Click here for posts measuring 7”, 7-1/2” and 8” square.

Custom sizes available: Call or email us at for details, pricing, and availability.

*Must be Painted: Texture of bare material can look rough. With just one coat of paint, the texture will return to a smooth, shiny finish.

Product Details:

  • Qty: 1 Azek Post Cap
  • Post Cap only - NOT a light
  • Impervious to Insects and Moisture
  • Will not rot, split, twist, or warp
  • Must be painted
  • Quality craftsmanship
  • Made in the USA
  • Manufacturer: Nantucket Post Cap
  • Outstanding 25-year warranty on Material Defects

Product Dimensions:

Order by post size: Measure the length and width of your post for the best fit. Post Cap opening will be 1/8" larger to allow the wood to naturally expand and contract.

*All measurements shown in inches.

Post Size Opening Size Moulding Height Product Size (LxWxH)
3-1/2" 3-5/8" 1-1/2" 5.75 x 5.75 x 3 
3-3/4" 3-7/8" 1-1/2" 6 x 6 x 3 
4"  4-1/8" 1-1/2" 6.25 x 6.25 x 3 
4-1/2" 4-5/8" 1-1/2" 6.75 x 6.75 x 3 
4-3/4" 4-7/8" 1-1/2" 7 x 7 x 3 
5" 5-1/8" 1-1/2" 7.25 x 7.25 x 3
5-1/2" 5-5/8" 1-1/2" 7.75 x 7.75 x 3
5-3/4" 5-7/8" 1-1/2" 8 x 8 x 3
6" 6-1/8" 1-1/2" 8.25 x 8.25 x 3
6-1/2" 6-5/8" 1-1/2" 8.75 x 8.75 x 3



For a nail-free look, simply apply an exterior marine adhesive like 3M 5200 to the top of the post and slip the post cap over. Stainless steel nails may be used as an alternative, but not necessary.

Product Care

Azek products must be painted prior to being installed or they will discolor and void the warranty.

The following is recommended:

  • Azek doesn't have a finish and that leaves the material subject to dirt, smudges, mold, and mildew.

  • Properly prepared and painted with even brush strokes gives it the appearance of finely painted wood.

  • A properly painted finish will last for years, protecting the substrate from mold, mildew, and UV rays.

  • Surfaces must be clean, dry, and void of any foreign material such as dirt, oil, grease or other contaminants that may come from normal handling, storage, and/or installation prior to painting.

  • Use 100% acrylic latex paint with colors having a Light Reflective Value (LRV) of 55 or higher.


Shipping: This product ships directly from the manufacturer's warehouse in Vermont. Caps are built after the order is received. Orders typically ship in 1-4 business days via UPS Ground and will arrive within 1-5 business days from the ship date. 

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