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

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


Azek Federal Post Cap for 4x4, 5x5 to 6x6 posts is made in the USA and handcrafted with pride by Nantucket Post Caps. Made of polymer PVC that resists scratches, stains, mildew, and moisture damage. The Federal is a popular style offering a classic pyramid top design with rounded edges. Slips over the top of your posts for easy DIY installation.

Our Azek post caps are cut and milled from 100% real Azek boards and are available to fit a variety of post sizes, including custom sizes. These caps are not copies so will not have the same dimensions as authentic Azek post caps.

*Must be painted: Our caps do not have the same finished surface as authentic Azek post caps so the texture of the bare material can look rough. With just one coat of latex paint, the texture will return to a smooth, shiny finish. Painting also helps to seal the exposed cells and unlike painted wood, the paint finish should last for many years.

Available Sizes: The Azek Federal is fabricated to fit a variety of post and post sleeves measuring 3.5” to 6.5” square. See actual product measurements and how to order the correct size in the "Product Dimensions" section below.

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

Custom sizes available: Call or email us at for details and availability. Just let us know what size you need. Typically the price will be the next size up.

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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