Mailbox Post Installation — Replace a Rotted or Frost-Heaved Post
The mailbox post leans a little more every spring, the bottom is rotted where it meets the ground, or the plow took it out. We set a new post that stays plumb through a Minnesota winter.
Mailbox post installation is a small job done right or done again every spring. JMB Builders sets a cedar, treated or PVC-wrapped mailbox post at the postal service's height and setback from the road, in a base that resists frost heave and can take a plow's snow, and mounts your mailbox on it. Done across the Twin Cities metro, priced per unit, quoted from your photos within one business day. Locates are called in before we dig.
- Priced per unit (each post)
- Cedar, treated or PVC-wrapped posts
- Set to postal height and setback
- Utility locate called in before digging
- Licensed MN contractor BC809005
A mailbox post fails two ways in Minnesota. It rots at grade, where the wood goes from wet to dry every day, and it heaves, when the frost grabs the post or the concrete around it and lifts it a little each winter until it leans. A post set in a shallow blob of concrete is the one that heaves worst, because the frost has something wide to grab. A post that rots at the ground line is the one that was set in dirt or in concrete that cups water at the top.
We set posts so neither happens. The hole goes below the frost line where the ground allows, the post sits on gravel so the bottom drains, and the backfill is tamped so there is no wide concrete collar for the frost to grip. Where the ground is rock or the road shoulder is too hard to dig, a driven post sleeve or a concrete pier with a bracket that keeps the wood off the ground does the same job. Either way the post is plumb and the box is at the height and setback the postal service wants.
Style is your call: a plain treated post, a cedar post with an arm and bracket, a PVC sleeve over treated so it never needs paint, or a post that takes the box you already have. On a road with a plow, the post should be a single post the plow can knock without taking the road with it, not a masonry column.
What you supply
- Photos: the current post from the road, a close-up of the base, and the mailbox you want on it
- Post style: treated, cedar with an arm, or PVC-wrapped, and paint or stain color if you want it finished
- The mailbox, or we supply a standard box in black or white
- Your house number if you want it on the post or the box
- Any rule from your city or homeowners association about post style, which you can check before we order
What JMB supplies
- Removal and haul-away of the old post and any concrete around it
- A utility locate called in before we dig
- New post: treated, cedar with arm and bracket, or a PVC sleeve over treated, set plumb
- Hole dug below frost where the ground allows, gravel base, tamped backfill or a pier with a standoff bracket
- Mailbox mounted at the postal height and setback, house numbers installed if you want them
- Photos of the finished post in your job folder
- Painting or staining a cedar post when you want it done, quoted as its own line
How it is priced: per unit
Quoted in writing from your photos within one business day. What moves the number:
- Treated post vs. cedar with an arm vs. PVC-wrapped
- Old post in a concrete footing that has to be broken out
- Ground that can be dug vs. rock, road base or a shoulder that needs a driven sleeve or pier
- Mailbox supplied by you vs. by us, and house numbers
- Two or more posts on the same trip, common on a cul-de-sac or for neighbors
- Distance out from the metro
Tell us whether the old post is in concrete and whether a plow runs the road. Those two things set most of the price.
How long it takes
One post: two to three hours on site, after the locate is in. Concrete removal or a pier adds an hour or two. Posts on the same street go on the same trip.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized quote within one business day. We only come out to measure first when the job needs a tape measure — no pressure, no games.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Treated post, direct set
A plain treated post set below frost on gravel with tamped backfill. The cheapest post that stays plumb. Paint or stain it, or leave it to weather.
Cedar post with arm and bracket
A cedar post with a horizontal arm and a bracket under it, set the same way. The box hangs on the arm so the post can be back from the road edge. Stained or painted as its own line.
PVC-wrapped post
A PVC sleeve and cap over a treated post, with a PVC arm. White, never needs paint, does not rot at the ground line. The look most newer subdivisions ask for.
Pier and standoff bracket
Where the shoulder is rock or road base, or where the post keeps rotting at grade, a small concrete pier with a metal bracket holds the post off the ground. The wood never touches dirt.
Mailbox Post Installation — Replace a Rotted or Frost-Heaved Post: questions, answered
Why does my mailbox post lean after every winter?
Frost heave. When the ground freezes it expands and grabs whatever is in it. A post set in a shallow, wide plug of concrete gives the frost a lot to grab, and each winter it lifts a little and does not settle back the same way. A post set deeper than the frost reaches, on gravel, with tamped backfill instead of a concrete collar, has nothing for the frost to lift. That is how we set them.
How high and how far from the road should a mailbox be?
The postal service publishes a height for the bottom of the box above the road surface and a setback from the curb or road edge so the carrier can reach it from the vehicle. We set the post to that guide. Your city or township may add a rule about posts on plowed roads, and a homeowners association may specify the style. Check those before we order the post; the height and setback we take care of.
Should a mailbox post be set in concrete?
Not in a big shallow blob. Concrete holds water against the post at the top and gives frost something wide to grip. We set most posts on a gravel base with tamped soil, which drains and holds. Where the ground is too loose to hold a post, a narrow concrete pier below frost with a bracket that keeps the wood above grade is the better use of concrete. A post in a proper base does not move, with or without concrete.
Do you call for a utility locate before setting a mailbox post?
Yes, every time. Gas, electric, cable and fiber lines run along road shoulders, right where a mailbox post goes. We call in the locate and dig after the marks are down. It adds a few days between the quote and the install, and it is not optional.
What kind of mailbox post will the snowplow not destroy?
A single post set back to the postal setback, with the box on an arm so the post itself is farther from the road edge. Plows throw heavy snow, and a post that can take a hit and stay put is a solid treated or cedar post in a good base. A masonry column or a post right at the road edge is what the plow wins against. If the plow hits the box itself, that is a box problem, not a post problem.
Can you put the new mailbox on my old post?
If the post is plumb and sound, yes, and we tell you that from the photos so you do not pay for a post you do not need. Most calls are for a post that is rotted at the ground line or leaning, and then the post is the job. Your existing mailbox goes on the new post if it is in good shape, or we supply a standard box.
Get a written quote for this job
Three photos and a sentence is enough. You hear back within one business day. Or text the photos to 763-204-2099.
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Read morePage reviewed September 24, 2026 · JMB Builders LLC, MN license BC809005 · All exterior trim pages
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