Email and texting have all but eradicated hand written letters. But your home still needs a mailbox. After all, who’s heart doesn’t pitter-patter at the sight of bills and other junk mail? Mine sure does! Plus it provides the bulk of my recycling bin’s daily fiber intake. In related news, I need to upgrade my ratty old blow-molded mailbox to something a little more substantial. If you’ve ever wanted to build and/or install your own curbside mailbox post, we’re going to walk you through the process.
Wait A Minute, Mr Postman – It’s Time For A New Mailbox
When I’m not writing for Home Fixated – or doing “independent QC” on assorted microbrews – I can be found hunting unique and collectible items to resell online. For days when there are only a handful of orders going out (and/or nothing that’s really big), a larger mailbox would save me a trip to the post office. So I stepped up to Gibraltar’s extra-large capacity ST200B00. Up close, this thing is almost comically large, but it’s exactly what I need.
The post we’re building today works with mailboxes of any size, whether your child can fit in it or not. The core project consists of three main parts: a tall vertical post, a horizontal mailbox “support arm” and a diagonal brace. Depending on the mailbox you choose, you may also need to add a flat mounting platform.
Note that the United States Postal Service (and probably whoever carries the mail in your neck of the world) has regulations regarding curbside mailboxes. These postal regulations and requirements are worth a careful read.
Mail Wood And Hard-ware – Hunting And Gathering
Our journey begins with a trip to the home center. In addition to the materials listed below, you will need hardware to attach the mailbox. And, if you want the mailbox to sit on a platform, wood to make said platform (I trimmed a scrap of 2×12 for mine) and lag screws and washers to attach it to the post. All of the wood is pressure treated and the hardware is galvanized.
* Mailbox (USPS approved)
* (Qty 1) 8-foot 4×4
* (Qty 1) 6-foot 4×4
* (Qty 2) 5/16” x 3” lag screws
* (Qty 2) 5/16” x 3-1/2” lag screws
* (Qty 4) 5/16” flat washers
* (Qty 4) 5/16” split lock washers
* 2 bags of concrete. You may or may not need it all, but have two bags on hand. (I used approx. 80 lbs.)
* Quart of exterior grade paint
If your new mailbox needs a platform, add 2-3 more sets of 5/16” x 3” lag screws w/ flat washers and split lock washers. I used 3 on mine.
Getting Started On How to Build a Mailbox Post – A First Class Project
Start with the main, vertical post. Grab the 8-foot 4×4 and mark a line 24” from one end (the bottom). This “ground line” shows you how deep to bury the post. The horizontal support arm mates to the main post with a half lap joint. The next step is to position that joint.
According to USPS guidelines, the bottom of the mailbox should be between 41” and 45” higher than the surface of the road. The road; not the ground the post is buried in. If your yard is higher or lower than the road, adjust accordingly. Either way, the first 24” of the post should be buried. Then add the mailbox height to that.
In my case, I measured 41” above my “ground line” (65” from the bottom of the post). This is where the top of the half lap joint – hence the top of the horizontal support arm – will be. After I add my mailbox support platform, the inside bottom of the mailbox will be about 42-1/2” inches higher than the road.
Part And Parcel – The Half Lap Joint
The half lap joint is just a pair of dadoes that fit into each other. You can hog away the waste material with your circular saw. But there’s an easier, usually faster, way.
SAFETY NOTE: You can’t see in most of the pictures, but the wood is always clamped at two points (to one or both tables) so it can’t move while I’m making my cuts. Failure to secure the workpiece can lead to injury. Injuries bad, mmmkay?
Rather than trying to remove all of the material with your saw, make a bunch of separate cuts, as shown. Then knock out the waste wood and clean up the bottom with a chisel.
Dado The Support Arm
The horizontal mailbox support arm is cut from the 6-foot 4×4. Select the better of the two ends (you can trim a little off if you need to). Leave about 5” then lay out and cut the other side of the half lap joint.
Mail Revue – Hunk It Up With A Decorative Touch
This mailbox post is based on a classic design. And true to tradition, we’re dressing it up with simple design elements: a pyramid at the top and an accent cut below that.
I used the new mailbox to gauge where I should lay out my decorative accents. There is an accent cut 1”-2” above the top of the mailbox. Then a pyramid “finial” about 4” above that. These are purely aesthetic and can be altered to taste.
Pyramid Scheme In A Mail Dominated Industry
The next two pictures serve to (hopefully) prevent any potential confusion concerning the angled marks you may notice in a bit. You do not need to draw them on yours.
I’ve already done the “figuring out”, so you can skip the whole triangle layout part. Just mark off a blank inch of material. That inch will become the ornamental pyramid.
Trim The Main Mailbox Post And Support Arm To Length
Determine how long the mailbox side of the support arm needs to be for your particular mailbox, then trim it – and the main post – to length. The bottom edge of some mailbox doors (like my new one) tuck underneath the body when opened. Make sure the support arm won’t hinder movement of the door.
Alpha Mail – Cutting Decorative Elements Into Your Mailbox Post
You can certainly get by without these cosmetic touches. But for the little extra time they take, they make a big difference in appearance. And if you want to tweak them to better suit your taste, do it! This is your how to make a mailbox post project too.
To cut the pyramids that adorn the ends of the post members, angle the sole plate of your circular saw to 30°. Cut along a reference line drawn an inch from the end of the post, on all four sides.
Pushing The Envelope – A Small Variation For The Mailbox Support Arm
Admittedly, there isn’t a lot of “envelope pushing” going on here. But I’ve complied a list of mailbox puns and, since most of them won’t work for this project article, I need to use what I can when I can. ‘Cause frankly, I’m not finding much opportunity for contrived references to my “package” or pop singer “Post Mailone”. But when a sassy pun wants to heard, one must letter speak!
Mail Bonding – Joining The Two Main Parts
The parts fasten together with lag screws. But first, we need to drill holes for each screw location. Start by drilling counter-sinks into the support arm.
Use a Forstner bit (or paddle bit) to make two holes large enough for the flat washers and deep enough to just sink the heads of the screws.
After drilling the counter-sink, drill a pilot hole. A pilot hole prevents splitting by giving the shank of the screw somewhere to go.
I made 7/32” pilot holes. But with harder wood, a 1/4” pilot is commonly recommended for 5/16” lags. For best results, test on a piece of scrap to determine what works best with the wood you’re using. Finally, separate the two pieces and enlarge the holes in the support arm (the piece with the counter-sinks) to 5/16”.
Mail Support Group – Brace Yourself (And Your Mailbox)
The diagonal brace is cut with a 45° angle on each end. The brace is attached with two 3-1/2” lag screws.
The Post With The Most – Prep And Paint That Mofo
Now that you’ve successfully built your mailbox post, take it back apart! Sand or wire brush all of the wooden parts then give them a couple coats of exterior grade paint. I chose a green that matches the shutters on the home. Let it dry overnight before installation.
Post Mental Pause
Rock the old post back and forth until it’s loose enough to lift out. It may take some extra persuasion and you may have to dig a bit if it’s anchored in concrete. In this case, however, not only was it not anchored, it was only buried 10” deep. Geesh, how was this thing even standing?
Going Postal – How to Install a Mailbox Post
If you’re installing a mailbox at a fresh location, you should first have the area checked for any underground utilities.
According to Post Office guidelines, the front of the mailbox should be set back 6-8” from the edge of the road. This required my moving the existing hole back several inches. And of course, to deepen it to 2 feet. The 4×4 post should be able to sit in the hole with 3-4” of clearance all the way around.
Tamp the bottom of the hole a few times, verify that it’s right at 2 feet deep, then insert the post. Be sure the front is turned parallel to the road. For visual reference, you can hold a yard stick against one side of the post and extend it towards the road. This “pointer” helps to judge if the post is properly squared up to the road.
Keep Me Posted – In Concrete
Assuming you followed the Postal Service guidelines (front of mailbox 6″-8″ from the road and the bottom of the mailbox 41″-45″ higher than the road) – and oriented the post properly (double check to be sure you have the correct side facing the road) – you’re ready to set it and forget it.
Rather than mix the concrete first, you can pour in several inches of dry concrete then splash in enough water to completely wet what’s there; it will probably take less than you think. Poke, prod and mix until you see no more dry powder (I used a piece of rebar as a stir stick). Then add a little more concrete, water, mix, lather, rinse, repeat. Remember to check for plumb a few times during this process.
Continue filling the hole until you’re about 4” from the top. When the surface of the concrete hardens (maybe an hour or so), top it off with dirt. Finally, remove the bracing and assemble the mailbox post. It can take six hours or more for concrete to truly set (and several days to fully cure), so don’t be too rough during assembly.
All that’s left to do is paint the exposed hardware and screw the mailbox into place. This new mailbox will save me a ton of time and gas money. And my “mail escort” won’t have to leave as many packages out in the rain.
I always feared: What if there’s not enough room for the endless piles of “last chances” to win some clearing house’s sweepstakes? Or all of those fake keys the car dealerships send out, coupled with promises of either a big screen TV or a coupon for $5 off of a new car: just for showing up! But I shall worry no more; this mail beast has room for all of that junk mail and so, so much more!
The extra large capacity mailbox we used can be purchased for under $27.00. This one is black, but other colors are available as well.
Call before you dig:
USPS mailbox guidelines:
More information regarding official requirements for city delivery mail receptacles: