Best Method For Setting A Post | Fence, Deck, & Mailbox

There are a lot of different methods for setting 4x4 and 6x6 posts. I have made many mistakes over the years and combined my lessons learned into this ultimate guide to properly set a post for your fencing, deck, mailbox, or other DIY projects. In addition, I will show you a way to extend out the life of your post by 2X or 3X and avoid the most common point of failure.

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[EverydayHomeRepairs]

DISCLAIMER: This video and description contain affiliate links, which means that if you click on one of the product links, I’ll receive a small commission.

[Rado]

Ex fence builder here. We used to have a garden hose handy to spray water into the hole while pouring in the concrete at the same time. The concrete will also draw ground moisture as well. Also, we eliminated the need to stake the post by just holding the post close to plumb while dumping in the concrete, and then bumping it into level after the concrete was in the hole. As long as the post wasn't bumped afterwards, we never had an issue.

[cuthwulf]

My dad and I used to install posts for our neighbors and friends to help out around the farms in the area. You can avoid wheelbarrows and a lot of mixing by doing exactly what you did, but putting in 1/3 of the bag, pouring 1/3 water, then more powder, then water, and so forth in 3 or 4 increments. You don't need to stir or mix, but by adding the water at certain levels, it soaks in up and down and the whole thing sets. Never had a post fail due to concrete.

[robrig]

I like how you sacrificed a spot in your well-kept yard just to make this helpful video. You're the man.

[beotheguitarist]

Scott is just awesome. I'm a building mechanic here in Connecticut and I do electrical, plumbing, and carpentry. Even though I've been doing this work for 30 years, I love to watch these videos because I'm always learning something new. Scott always does things the right way and will go into detail on how things are done. You're never too old to learn things!

[camepps]

Growing up, my grandfather would always dip the ends of posts in used motor oil to seal them. He told me that if it starts to rot anywhere, it will begin at the endgrain because it’s like straws for the wood. I typically paint the ends instead of motor oil, but something else to think about

[scomi]

Two things. Pouring dry concrete on top of your gravel will just give you very gravelly concrete at the bottom of the hole. It will not give you the drainage you're looking for. Also, the concrete at the bottom of the hole, that was still dry after a few hours, will set up over the next days and weeks as it draws moisture from the ground.
I do like the flex seal idea. That's a lot less of a mess than using a small roller and thinned roofing tar that I have used in the past when building a fence.
Great video though. Most YouTubers just film themselves doing something. You actually purchased all the supplies and did all the work for the video.

[rustycrab]

This was excellent. You answered a lot of "what if" questions for those of us who might be attempting this for the first time.

[JustSayNO]

In 2011, my newly constructed house needed a mailbox. (Southern USA, no freezing, ever) I set the 4x4 into the ground as usual and used Quickrete. About 2 years later, the post became loose. However I cannot remember if the post was able to be wiggled within the concrete, or the concrete was able to be wiggled within the dirt hole. Doesn't matter. Had to be removed at that point.

Needing to replace and upgrade to a nicer mailbox, I dug the entire first one out including the concrete. Then I set a new post in the same hole, but this time using expanding foam. That was 10+ years ago and the mailbox post is still rock hard sturdy. Zero wiggle. It was the first time I ever had used it. Totally miraculous. Recommend without reservations.

Since the foam I used expanded somewhat above ground, the next day I began cutting the excess using a box cutter. The foam was very tough, definitely did not allow finger-poke-holes or even indentations, and really resisted being cut. So I switched to a hand saw which did the trick, using the box cutter only for the foam up against the wood. It's possible that you removed your experimental foam cylinder and tested it too soon. Despite what the manufacturer wrote on the package, the polyurethane probably needed well more than only two hours to fully cure.

By the way, my newer mailbox post has one modification. I screwed in four thick, exterior lag screws into the underground portion of the 4x4, one on each side, several inches below the ground level. This was so the expanding foam would have more surface area to grab onto as it solidified around the mailbox post. The screws protruded about 3 inches from the post. That is, they weren't screwed all the way in. Probably this is why my post remains so incredibly sturdy more than a decade later. What is your opinion on that?

I like the idea of FlexSeal and will use it next time. The clear version. And I will spray the entire underground portion, not just a few inches above and below the ground level. Do you think that is wise? At least one commenter wrote that it separated/expanded somewhat from his post resulting in it being a rainwater collector, if I understood his comment correctly.

I plan to upgrade my mailbox again later this year because the sun and rain have been taking its toll on the wood above the ground. I'll do it in December when it cools down outside !!

[ItIsJustDan]

Protip, if you really want that post to sit into the concrete, add some random nails/screws to the bottom of the post and add concrete into the hole. This way when the concrete dries, it'll literally have something to "bite" that's connected to the post. It'll be a PITA to take the post out if the post falls from a hurricane or tornado but by that time, you're going to be in more trouble with something else than the fence.

[rquest]

I have always dumped one or two buckets of water into the hole first, then put the cement in, then put water on top. That way, the cement draws the water from both ends, and any excess water soakes into the soil.

[philipcaldwell]

My frost line is around six inches. I have pulled up 4x4 post where it was “dry set” by layering in about ten inches at a time with water on top and repeated until the hole pour is toppled off. Twenty years later I have had to remove some of these, during renovation projects, using the same method with a “HyLift” jack. They have all been perfect.

[timothyweiss]

I've always dug a 36" hole, add 6" gravel, level post. Always premix concrete and pour into hole. I bring it slightly above grade and bevel it away from post. Never had a issue and still strong at 30yrs. Take Care

[astewart]

Data point for fellow homeowners: 25 years ago I built a decorative front yard picket fence. Its structural needs were to not blow over in the wind, except for supporting the gate. It’s a bit less than 4’ tall. I used 3”x3” pressure-treated posts and 8’ pre-manufactured wood panels. I did use concrete for the gate posts, but the rest are just sunk into my heavy clay soil. I am in the South where frozen soil is not a concern. I painted everything with white primer. It still stands and still looks good. Not every fence needs to be set in concrete…

[erickjason]

In college for landscape design, we were taught to fill the hole halfway with water, then add the concrete mix(because it would be a wet mix) then finish off the hole. then smooth out the concrete always sloping it away from the post (there was no flex seal in the 80's). Great video, by the way. Your videos are always so clear and informative. Good job!

[johnlichtenthal]

I’ve always mixed in water as I go when I set posts. Specifically, I’d add about 1/3 or 1/2 a bag to the hole, add some water, then mix it together in the hole with a long-handled spade or thin shovel. Repeat the process until I had the amount of concrete I wanted in the hole.

[mikerisner]

The Flex Seal tip is absolutely great! I will definitely be doing that next time I set a post. As for the Quickcrete that was still powder, over time that dry powder will eventually draw moisture from the soil around it which will solidify the rest of the concrete. That said, it's best to fill the hole half way, then add a half gallon of water. Then fill the hole and add the other half gallon. I've done that several times in the past.

[kenmandu]

I recently pulled up a couple of 4 x 4 treated grape vine posts. They were placed with only dirt around them and had been in the ground for at least 30 years. What I saw was that even though the above ground portion was weathered with some cracking, the below ground portion still looked new. My guess was that the consistency of the below ground conditions was a good thing as compared to the variations of seasonal weather that the exposed part saw. Pretty amazing.

[WhatzTyme]

Absolutely the best course on YT DIY University! Great information! Thanks!

[octavernuez]

That's why I always premix the concrete, ..
Thanks for the information, ..