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6x6 Copper Post Caps
6x6 copper post caps fit a post measuring 5 1/2 to 5 3/4 inches. For a rough-cut post measuring 6 to 6 1/4 inches, choose the FULL 6" size of the Copper Pyramid Post Cap. Please measure before you order.
We have (7) 6x6 Copper products available.
Click one below to choose the 6x6 size.
Why a 6x6 post needs a cap
The top of a post is end grain, the cut ends of the wood fibers. End grain takes in water much faster than the sides of a post, and a flat 6x6 end holds rain, snow and morning dew after every storm. That is where checking, splitting and rot usually start, and why the upper end of a post is so often the first part of a deck or fence to fail.
A post cap covers the end grain and carries water over the edge, clear of the post. It also protects the post from wind, wildlife and everyday outdoor wear, and gives every post a finished look. On a deck, fence, pergola or other outdoor structure, the 6x6 posts carry the load, and replacing one that has rotted is far more work than capping it when it goes in.
How to measure a 6x6 post
"6x6" is the name of the post, not its measurement. A post sold as 6x6 at a lumberyard has been planed smooth on all four sides, and it measures about 5 1/2 inches across. Our standard 6x6 caps fit a post measuring 5 1/2 to 5 3/4 inches.
A rough-cut post has not been planed, so it measures a full 6 inches or slightly more. That post needs a FULL 6" cap, which fits a post measuring 6 to 6 1/4 inches. Ordering the wrong size is the most common reason post caps are returned, so measure every post before you order.
| Your post | Measures across | Cap size to choose |
|---|---|---|
| 4x4 | 3 1/2 to 3 5/8 in | 4x4 |
| 4x4 rough-cut | up to 4 in | FULL 4" |
| 4x6 | 3 1/2 x 5 1/2 in | 4x6 |
| 5x5 | 4 1/2 to 4 5/8 in | 5x5 |
| 6x6 | 5 1/2 to 5 3/4 in | 6x6 |
| 6x6 rough-cut | 6 to 6 1/4 in | FULL 6" |
| 8x8 | 7 1/2 to 7 5/8 in | 8x8 |
| 8x8 rough-cut | up to 8 in | FULL 8" |
On this page, the FULL 6" size is available in the Copper Pyramid Post Cap. The other caps here come in the standard 6x6 size.
Where to measure
Measure across the flat face at the very top of the post, from one side to the other. Do not measure corner to corner, and do not measure partway down. Measure in both directions, because an older post is often no longer perfectly square, and use the larger figure. If the post is cut at an angle, measure the widest part of the cut.
Five things to check before you order
Pressure-treated lumber shrinks as it dries. A new post that is still wet can measure slightly larger than it will in a few months. If your measurement is near the top of a range, measure again before ordering.
A wrapped post is larger than the post inside. If the post has trim boards or a sleeve around it, measure the outside of the wrap.
Vinyl and composite sleeves vary by manufacturer. Measure the outside of the sleeve and match the figure to the table above.
A stair or corner post is sometimes cut at an angle. Measure the widest face of the cut.
A split or soft post top needs attention first. Cut back to sound wood before the cap goes on. A post cap protects a sound post. It will not repair one that has already started to rot.
Ordering for a whole project
Measure every post, not just one. Sizes on the same fence or deck can differ, especially on older projects or where a post has been replaced over the years. Write down the size of each one and group them, so you order the right number of standard and FULL caps.
What the 3/4" lip does
Every cap on this page has a lip that drops down over the sides of the post. On the all-copper caps it is 3/4 of an inch deep. The lip covers the end of the post and the upper part of each side, which keeps rain off the end grain, where wood takes in water fastest. Before ordering, check that you have 3/4 of an inch of clear post below the end. A railing bracket or fence rail fixed right at the end of the post can get in the way.
How 6x6 post caps install
The caps on this page install two different ways, depending on what they are made of.
All-copper caps: two screws, included
The all-copper caps, including the finials, slip over the post and fasten with two screws, which come with every cap. Set the cap in place, check that the lip sits evenly on all four sides, and drive one screw through the lip on each of two opposite sides.
The finial caps ship in two parts, the copper base and the finial top, so the finial is protected in transit. Put the two together before you mount the cap.
If you ever replace a screw, use copper or stainless steel. Plain steel and galvanized screws react with copper and can leave dark streaks down the post.
West Indies wood caps: construction adhesive
The West Indies Miterless Wood Post Caps™ are a one-piece mahogany base with a separate copper lid. They glue onto the post with construction adhesive such as Liquid Nails, which is sold separately.
1Make sure the post top is flat and dry. Adhesive does not bond well to wet wood.
2Apply construction adhesive to the end of the post, following the directions on the tube.
3Set the base on the post and check that the lip sits evenly on all four sides.
4Attach the copper lid to the base.
5Wipe away any adhesive that squeezes out before it sets.
One piece of copper, no corner seams
All Post Cap Depot copper products are stamped from a single piece of 20-gauge copper, a heavier gauge than most copper post caps. There are no soldered joints at the corners. Corners are where seamed post caps fail: once a joint opens, water runs onto the post instead of off it. Our caps are guaranteed for life never to split apart at the corners, and the Miterless Wood Post Caps™ carry the same guarantee.
What copper does over time
Copper post caps are not painted or coated, so outdoors there is nothing to peel or wear off. What changes over time is the color. The photos below are Post Cap Depot copper caps on customers' fences and decks at different ages.
New
Bright
Caps arrive bright, close to the color of a new penny.
First months
Warm
The shine dulls and the color warms toward bronze.
A few years
Bronze
The color deepens and evens out along the run.
Long term
Dark brown
Dark brown, with copper still showing in direct sun. In wet or coastal climates a green patina can follow.
What changes the speed
Rain, humidity and salt air speed the change up. Caps under trees or a roof overhang change more slowly than caps in open weather, so caps along the same fence can sit at slightly different stages for a while before they even out. A new cap added to an older run will look brighter until it catches up.
Will copper stain the surface below?
Rain running off copper can carry a faint green or brown tint onto white vinyl, white stone or light concrete directly below the cap. It is most noticeable while the copper is new.
Keeping the original shine
If you prefer bright copper, a clear protective spray made for copper preserves the original sheen. It is sold separately and needs reapplying as it weathers. Without it, the caps patina naturally.
Hammered or smooth
Hammered copper catches the light across many small facets instead of one flat surface, so it hides fingerprints and water spots and looks more even on a post in part shade. Smooth copper has a cleaner, more modern look and shows the color change more evenly along a run.
Choosing a 6x6 copper post cap style
Every cap on this page fits a standard 6x6 post measuring 5 1/2 to 5 3/4 inches. The difference is the look. Choose Options on any product above to see its details, sizes and current price.
| 6x6 copper post cap | Top | Mounting | FULL 6" size |
|---|---|---|---|
| Copper Pyramid | Smooth, peaked | 2 screws, included | Yes |
| Hammered Copper Pyramid | Hammered, peaked | 2 screws, included | No |
| Flat Copper | Flat | 2 screws, included | No |
| Copper Pineapple Finial | Pineapple finial | 2 screws, included | No |
| Copper Federal Globe Finial | Globe finial | 2 screws, included | No |
| West Indies (copper lid) | Mahogany base, copper lid | Construction adhesive | No |
| West Indies (hammered lid) | Mahogany base, hammered lid | Construction adhesive | No |
Every all-copper cap here is stamped from one piece of 20-gauge copper with a 3/4" lip. The finials ship with the finial top separate from the base.
Pyramid
A raised top that sheds water quickly and suits almost any fence or deck. It is also the one cap here available in a FULL 6" size for a rough-cut post.
Hammered pyramid
The same shape with a hammered texture that hides fingerprints and water spots. Also available in 4x4, 4x6 and 8x8.
Flat
A low, flat top with the same 3/4" lip. It suits horizontal-slat fences, modern decks and white or gray painted fences where a peaked cap would look too traditional. Also available in 4x4, 4x6 and 8x8.
Pineapple and globe finials
A pineapple or federal globe finial on a copper base. Often used to mark a gate, corner or entry so it stands out from the rest of the run. Both are available in 4x4 as well as 6x6.
The two West Indies caps pair a one-piece mahogany base with a copper or hammered copper lid, for a wood fence or deck where you want copper on top. A common approach on a long fence is the smooth copper cap along the run and finials at the gates and corners.
Where 6x6 copper post caps are used
6x6 is the post size builders reach for wherever a post carries real weight or strain, so the 6x6 size covers a wide range of outdoor projects.
Decks. Railing and support posts on decks built with 6x6 lumber, including the newel at the top and bottom of each stair.
Fence gates and corners. Many wood fences use 4x4 line posts with a heavier 6x6 post at each gate and corner, where the fence takes the most strain. A copper cap sets them apart from the rest of the run.
Pergolas and arbors. Outdoor structures that stand in open weather on every side, where a cap protects the post and finishes the look.
Mailbox posts. A 6x6 mailbox post takes the same cap as a fence post.
Docks. Square dock posts. Round pilings take our round piling caps instead.
6x6 post caps in other materials
Copper is one of four materials we make 6x6 post caps in. They fit the same post and look very different.
6x6 Copper Post Caps
This page. Stamped from one piece of 20-gauge copper and left to patina naturally.
Shop 6x6 Wood Post Caps
Miterless Wood Post Caps™: one-piece wood caps with no mitered corners to open up. They can be stained or painted to match the fence.
Shop 6x6 Black Post Caps
Black stainless steel tops, including a West Indies mahogany cap with a black stainless lid. A dark finish that sits quietly against black railing and dark-stained wood.
Shop 6x6 Stainless Steel Post Caps
Stainless steel stays bright and does not develop a patina.
Questions about 6x6 post caps
My post measures 5 1/2 inches. Which size do I need?
A standard 6x6 cap. A planed 6x6 post measures about 5 1/2 inches, and our 6x6 caps fit a post from 5 1/2 to 5 3/4 inches.
What is a FULL 6" post cap?
A cap for a rough-cut post measuring 6 to 6 1/4 inches. On this page it is available in the Copper Pyramid Post Cap.
Will a 6x6 post cap fit a 5x5 post?
No. A 5x5 post measures about 4 1/2 inches, so a 6x6 cap would sit loose. Choose a 5x5 copper post cap instead.
Are screws included?
Yes, with the all-copper caps. Each comes with two mounting screws. The West Indies wood caps mount with construction adhesive, sold separately.
What is the difference between the copper caps and the West Indies caps?
The copper caps are copper throughout. The West Indies caps are a one-piece mahogany base with a copper or hammered copper lid.
What if I order the wrong size?
Call or email us for a return authorization before sending anything back. New, unopened items can be returned within 30 days of delivery. Returns carry a 20% restocking charge unless the product is defective. We do not refund the original shipping charge, and return shipping is at the buyer's expense unless the error was ours, so please measure first. Our Shipping & Returns page has the full details.
Is there a warranty?
Yes. Our post caps are guaranteed for life never to split apart at the corners. If a product does, we replace it with a product of equal value.
How many post caps do I need?
One per post. Count every gate, corner and stair post as well as each line post.
How do I clean copper post caps?
Rinse them with water and wipe with a soft cloth. Avoid abrasive pads and harsh cleaners, which scratch the surface.
Do the caps fit a painted or stained post?
Yes. Paint and stain add almost nothing to the size of a post. Measure the finished post and choose the size from the table above.
Not sure which product is right?
Call us at 678-909-2720 with your post measurements and a description of your fence or deck.
Shop copper post caps in other sizes
4x4 Copper Post Caps · 5x5 Copper Post Caps · 4x6 Copper Post Caps · 8x8 Copper Post Caps