How to Repair a Split Wood Post

Over time as wood ages and is exposed to large temperature and moisture swings in the outdoors, cracks will appear.  This is especially so when wood becomes extremely dry.  This is the natural way of things, and wooden posts are no exception.

You’ll notice this happening in fence posts and gate posts, no matter the wood, whether cedar or pressure-treated spruce or pine.  Or maybe it’s a post that supports the deck where you sit at the end of a long day with a cold beer.

While a cedar or pressure-treated post will resist rot, insects, and decay, they are not immune to cracks or splits.  However, that is not necessarily a cause of structural concern or worry, and as long as it hasn’t snapped, there is hope. 

It won’t always be fatal to the integrity of the post, and it is possible to mend it.  In fact, it is possible to repair a fence, gate, or deck post without removing it.  And, no, duct tape is not the solution, although some tape does come in handy in the process of repairing a split wood post.

Filling the crack or split with something is the solution, and the something is glue.  The process is fairly straightforward, and we’ll walk you through one method we recommend.

What To Use To Fill Wood Cracks

Cascamite Powdered Resin Wood Glue 220g

A water-proof glue is the go-to product for filling these cracks and splits.  In particular, we suggest a powdered resin glue for this purpose.  A product like Cascamite powdered resin wood glue works well for this, adding both a filler and a bonding agent to provide structural strength in the process.

Cascamite will leave a clear glue line and does not discolor the wood.  It’s also mold-resistant.  It takes a couple of hours to lose its stickiness and 6 hours to cure fully in most instances, with temperature being the variant.  It’s an excellent adhesive and is used in cabinet work and boat building, among other uses.

The process is simple:

  • Follow the manufacturer’s directions closely when mixing the powdered resin glue with water.
  • Apply tape to the post over the bottom of the split or crack, and apply the glue into it with a brush, pushing it into the split with some force. If you have a few extra dollars, you would be better served, though, picking up a dripless glue dispenser, around $8 for a 16 oz size, as it will force the glue deeper into the split. 
  • Continue to add tape up the spill as you add glue until it is filled. The tape will act to hold the syrupy glue in the split while it dries and cures.  Don’t worry about excess glue on the surface of the post, as it can be removed with a chisel after it sets and dries.
  • To fill large cracks in the wooden posts, if the split is pronounced and wide enough to alter the shape of the post, use clamps from each direction around the post, an inch or so apart up the post, to close the split or until the glue begins to ooze out from behind the tape. We’ll talk about especially large splits shortly, where another filler/adhesive might be a better choice.
  • Optionally, with a large split, you can add strips of scrap wood into it after gluing if the clamping did not close the split. This can add some additional structural strength to the joinery.
  • Allow plenty of time for the glue to dry and cure, following the manufacturer’s directions. Then, remove the tape and chisel away any excess glue on the wood surface.
Cascamite Powdered Resin Wood Glue 220g
  • One-shot
  • Bonds stronger than the wood itself
  • Cascamite One Shot Structural Wood Adhesive Tub 220g
  • Polyvine

While the taping is not absolutely essential to the repair and can be skipped, it does hold the glue in place while drying and avoids waste.  This method of repair is effective on posts and beams of all sorts.

Adding a color to the glue might be something to consider, too.  Black plays well off wood, whether the wood is dark or light, and adding lines of black can add to the character and appearance of the posts.  Perhaps a red color might play well off any plants you may have along your fence or at a gate.  It’s not necessary, but you might like the effect.

If the wooden posts are showing some age or grayness, some of their natural beauty can be restored by applying linseed oil.  We have written of and mentioned using linseed oil in past articles, especially in this one

Linseed oil will penetrate deeply into the wood and add layers of protection from the elements and from aging.  It can be applied with a brush or a cloth, depending on the viscosity you have chosen, and 3 coats are what we recommend.

Will Epoxy Stop Wood From Splitting?

TotalBoat High Performance Epoxy Kit, Crystal Clear Marine Grade Resin and Hardener for Woodworking, Fiberglass and Wood Boat Building and Repair (Quart, Fast)

Epoxy is another bonding agent that provides greater structural integrity when used to fill gaps in wood.  We often see it today in furniture, perhaps in a dining room table or coffee table or shelving, of different colors that provide aesthetically pleasing appearances. 

An epoxy resin can be used to fill large cracks and splits effectively.  It is stronger than a resin glue and creates a strong bond in the wood.  This will prevent the split from getting any larger.  Its adhesive strength will hold the sides of the crack together and preclude further damage.

Again, as with resin glue, color can be added to an epoxy if you wish to add an additional aesthetic value to the post.  It works well and looks good in furniture, and it can do the same in posts and beams around your yard, whether fencing, gates, or decks.

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It’s not the end of the world to find splits in wooden posts.   They’re to be expected over time from the changing of the seasons.  The solutions are both easy and inexpensive, and you can do the work yourself. 

So don’t panic.  Your local hardware store, or online retailer, and the large DIY stores stock everything you need, and in less than a few hours, the work can be done and the glue or epoxy on its way to curing.  Just consider it routine maintenance around the home, the price of home ownership.

Last update on 2023-09-27 / Affiliate links / Images from Amazon Product Advertising API

1 thought on “How to Repair a Split Wood Post”

  1. I have half a dozen that need this, some 15 years old. I’ve found the upper end of a post with a hinged gate hanging from it is the most susceptible.

    Having used construction adhesive to set stone in a fireplace opening closed up for use with a wood stove, along with fixing loose stones in old mortar, and having some, Im going to use that. Inject plenty to fill, then clamp and let set up 48 hours. 2d step, add long deck screws to hold the split closed.

    Once complete the preventative fix is a post cap. I’ve seen quart milk jug bottoms stapled onto field posts, I cut 3.5×3.5 shields from gallon milk jugs and stapled them on top, then a simple treated top – they are sold premilled with a drilled hole in them. For more $$ they come in colors and even copper $$$. A looonng screw is needed to find good heartwood.

    Had I capped the posts 15 years ago I’d be ahead on this, and likely would have saved replacing the hinge and latch post on the pool deck. At least this time I leaned the hinge post away from the latch post, it’s slowly working its way to vertical but it has to drag the next one in the line to do it. Right now the vertical pickets are starting to look a bit slanty. I expect in another year or so I’ll back out the lower screw, put a level on them again, and run them straight.

    Of course, if they sold a clamping post cap you just tightened by twisting the top we’d all be perfectly happy.


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