How can I repair a snapped 4x4 mailbox post without digging out the footing?

Question

The mailbox is mounted on a 4x4 that was sunk into a concrete base about 18" below ground level. The 4x4 snapped off about 6" below ground. I really don't want to excavate the concrete and re-pour.

Is there a sleeve or joiner made that I could slide both sides of the snapped 4x4 into in order to secure each side with screws and join them (below ground) before re-mounting the mailbox? Where can I find something like this? The break on the post is jagged and I don't know that I can excavate the part of the post in the ground enough to square off the top so I could use a simple joiner with a plate in between the two post pieces. Any ideas?

Answer 1

Ground screw.

source

Screw this down through the old wood post. The depicted ground screw is 27 inches but I am sure you can find others if that is too long. The screw will be anchored in the old wood all the way down and through into the concrete. The top of the ground screw will hold your new post.

Answer 2

If it broke off below grade, you can fill in the original hole and use a drive-in stake anchor for a new post in a new spot.

As long as you have the ability to move left or right a foot or so, this should be viable. Note that you’ll still need to call to have buried utilities marked before driving in the new anchor.

Answer 3

This might be overkill, but it does solve the "no re-pour" requirement

1. Get some concrete and a single post tie designed to be put into concrete (i.e. for decking). You can typically find these in the area with pressure treat 4x4s. Make sure you buy fasteners as well (deck screws and/or galvanized bolts)
2. Pour concrete into the hole. Put your post-tie into your wet concrete and let it cure
3. Cut your new post to size and mount to the post tie

Again, this is overkill, but it would afford you a (theoretically) easier to replace post the next time around.

Answer 4

I had the exact same problem. I got a 6 foot dig bar and just chopped the heck out of the 12 inches of wood remaining in the square hole and was able to remove all of the wood. I got a new 4x4, cut it to the proper length and rammed it into the existing concrete hole and then screwed the mailbox on to the top of the new post. I've done this with fence posts many times too.

Answer 5

For what it's worth. You are only borrowing trouble if you don't remove the old post. The trick to removing a post is that you do not dig it out. You attach a jack to it and pull it out.

Your challenge is that your post is broken off. Drill a pilot hole and them use a 6" lag bolt to secure a piece of chain to your stump. Attach the chain to your jack and pull it like a tooth.

Answer 6

THIS ANSWER IS WRONG! I misread the question as the 4x4 having broken 6 inch ABOVE the ground...

With 6'' (15cm) above the ground remaining (assuming that those 6 inch are solid and you already trimmed off any splintered bits), you should have enough left to use angle joints*.

Cut off the bottom piece of wood in such a way that the most non-splintered wood remains (this can even be at an angle), then cut the new 4x4 accordingly (flat or in the mirrored angle as the bottom), then use two longer (or broader?) angle joints in the area where both pieces connect so that the wood is (almost completely or fully) surrounded by metal. Then drive in screws as you see appropriate. Ideally you want a really really long angle joint of 2x 6 inch, so you use all of the wood that's still in the ground for max stability

This solution would be by far the easiest, and with the right angle joints and enough screws also very stable.

*sorry for the German link, it's just to show you that somewhat right-sized angle joints exist [btw. I'm not even sure angle joints is the right word, but now you have a pic so you can maybe search with the right word]. The one linked is only 1.5 inches broad, so maybe too slim for a 4x4 (the broader the joint, the more stability), and with 7.8 inches on the shorter end, but a) I'm sure there are bigger ones b) with it being so slim you could use one for each corner instead of 2 angles c) even with just 2 of these it should be enough stability for a mailbox.

Answer 7

Can you dry everything thoroughly and just glue the 4x4 back together? It's a mailbox, so it doesn't cary a large load. You'll need waterproof glue. Probably polyurethane. You'll need to clamp the pieces together while they dry.

Would this help: https://www.homedepot.com/p/Simpson-Strong-Tie-E-Z-Base-Black-Powder-Coated-Post-Base-for-4x4-Nominal-Lumber-FPBB44/100655350 I'm not sure how large the broken area is, or how much access you have below ground.

You can use the "wings" on that product to attach a 1x4 along the sides of the post, if it needs extra support.

Answer 8

It happened once, it will happen again.

I'd start by getting as much of the old post out as possible. Perhaps a hole saw on the end of a longer shank would chew out the center. Another option is a larger forstener bit to munch the remains of the post.

(Updated - not recommended) If you're competent with a chainsaw it may be possible to plunge-cut downward and eat out the post from the inside. This needs a long bar and a chain you're prepared to damage if it kisses the concrete. Plus kickback could be horrendous. (I'm no chainsaw user, check with someone qualified)

A shop-vac would help to pull out dislodged pieces and keep drilling.

A crowbar or pry bar would help push splinters off the walls and corners of the hole.

You might be tempted to try and burn the wood in the middle out - however that runs the risk of cracking the concrete, presuming you can ignite a fire with limited air supply. Plus it will be treated wood and that's both hard to light and releases nasty chemicals once it is burning.

When the hole is clear, use a spokeshave to subtly taper the new post for the depth of the hole, and then sharpen the bottom 2 inches/50mm to a 90 degree point. Drop some sand or gravel, or some wet concrete into the hole and fit the post. The gravel will form a "cup" to reduce rocking due to the slight taper. Concrete will do the same but will form a socket.
Next time the post needs replacing, simply bring up your old measurements and carve a new post with a taper and point. Then either just lift out the stub by hand, or screw an eyebolt into the stump and lever it up and out.

You may need to cut one or two thin wedges to hammer into the post hole beside the post, to take up any slop. Or you could use a sealant around the top to try and minimise rain/snow ingress.

Answer 9

You can get a steel 'repair spur' that is designed to be driven into and around the broken post. They are shorter than normal steel post spikes

Alternately, you could fit a bolt down anchor over the hole (possibly filling the rest of the hole with concrete first)

Answer 10

Cut the top and bottom off of a 2-liter plastic bottle, forming a long cylinder. Slide this cylinder over the stump of the post. Apply wood glue to the surfaces of the post and then slide the remainder of post into the cylinder, matching the broken edges together. Then use a heat gun on the cylinder of plastic to shrink it tightly to the two halves of the post. -Note: I've never tried this, it's a suggestion I've seen on Youtube.

Answer 11

Another option is a fence-post mender from Simpson.

I don't know if it will work in your case, but I've had success with using them on fence posts that have rotted out inside the concrete footer (their stated use case).

In theory, you could bolt two ties on the bottom of your new 4x4, then drive the menders between the snapped off remains and the existing concrete. Might work after a lot of effort with a pile-driver, or a large sledgehammer if you don't happen to own a pile-driver.