Custom Toppers for Existing Fences.
Customer-supplied posts

Fence extenders

FenceTopper mounts on extension posts that you or your contractor add to your existing fence posts. Here are the options by fence type. Pick the one that fits your fence.

What’s a fence extender?

A fence extender is a post that attaches to an existing fence post and rises above the top of the fence. Your FenceTopper is strapped to these extenders, so they set where the panel sits and how tall it stands.

Add one on every fence post the topper spans, including both ends of each run. Each extender should rise about 1 in above the topper.

Side view of an existing fence post with an extender rising above the fence, the topper strapped to it, and the extender ending about 1 inch above the topper about 1 in Extender Topper Existing fence
The extender attaches to your existing post. The topper straps to it, with about 1 in of extender above. Not to scale.

Extender options

These are the options we’re testing now. Each one is still being tested, so choose the one that fits your fence and talk to us if you’re unsure. Seller links were checked in October 2026; prices and stock change.

Something else

Round steel posts

  • OZCO 3 ft internal post extender

    Being tested
    Fits
    2 3/8 in OD round steel posts
    Rise
    36 in tube, cut to length

    Locks inside the post, so the outside stays clean. Cut the tube 1 in longer than the topper on a level run.

  • Galvanized swaged extension

    Being tested
    Fits
    1 5/8, 1 7/8 or 2 3/8 in round posts (check the inside diameter)
    Rise
    Usually 24 in

    Slides into the post. Fasten it with screws or a through bolt; don’t rely on a friction fit.

  • Black swaged extension

    Being tested
    Fits
    1 5/8 in round posts
    Rise
    24 in

    Black finish. Comes with a cap and a self-tapping screw.

Wood fences and 4x4 posts

  • OUTDECO ODFE39 extension leg

    Being tested
    Fits
    Fastens down the face of a wood fence into rails or framing
    Rise
    13 to 16 in above the fence

    For shorter toppers, about 12 to 15 1/2 in. The 23 in leg stays visible on one side.

  • Side-mounted round or square pipe

    Being tested
    Fits
    Sound 4x4 wood posts
    Rise
    Cut to the length you need

    Lag-bolted into the side of the post through drilled holes or with clamps. Best done by a contractor.

Something else

  • Custom fence extension

    Fits
    Your own design
    Rise
    Your choice

    Describe it and send a photo or drawing, and we’ll review whether the topper can be adapted.

Choosing and installing

Cut length on a level run

When your post tops are level, cut each OZCO tube 1 in longer than the topper height. A 24 in topper uses a 25 in tube.

When post tops aren’t level

  1. Install the two end extenders and mark the top height you want on each.
  2. Stretch a mason’s line tight between the two marks so it’s level.
  3. Measure from the line down to each middle post top, and cut each middle extender to its own length.

Leave them a little long

When in doubt, leave the extenders a few inches long. Test-fit the topper, take it off and cut again. The topper goes on and comes off easily while you fit it.

OZCO tube length on a level run
Topper heightTube length
12 in13 in
13 in14 in
14 in15 in
15 in16 in
16 in17 in
17 in18 in
18 in19 in
19 in20 in
20 in21 in
21 in22 in
22 in23 in
23 in24 in
24 in25 in
Your responsibility

You or your contractor choose, buy and install the extensions. A taller fence catches more wind. Make sure your existing posts, footings and fasteners can carry it, and check your local height rules. FenceTopper doesn’t certify structure, wind load or code compliance.

Fence extender questions

Are posts included with FenceTopper?

No. You or your contractor provide and install the fence extenders, the posts that hold the topper above your fence. Our Fence extenders page shows the options by fence type, and FenceTopper builds the panel to fit your approved layout.

Which extender fits my fence?

It depends on your fence. Round steel posts take an insert-style extender sized to the post, such as the OZCO internal extender for 2 3/8 in posts or a swaged extension for 1 5/8 in posts. Wood fences can use a face-mounted leg or a pipe bolted to the side of a sound 4x4 post. Our Fence extenders page shows each option and what it fits.

How tall should the extender be?

Each extender should rise about 1 in above the topper. On a level run, cut an OZCO tube 1 in longer than the topper height, so a 24 in topper uses a 25 in tube. If your post tops aren’t level, set the two end extenders, stretch a mason’s line between them and cut each middle extender to meet the line.

Can I use my own extender design?

Yes. Describe it when you send us your project, or email us a photo or drawing with its profile and size. We’ll review whether the topper can be adapted to it. That review isn’t an engineering approval.

Do I need a contractor for the extenders?

It’s up to you and depends on the option. Side-mounted pipe on wood posts is best done by a contractor. Either way, make sure your posts, footings and fasteners can carry the taller fence, and check your local height rules.

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