I'm adding a new gate in my vinyl fence; a full width (6') gate.

I'm concerned about support. The fence posts are decently moored, but there is still some wiggle.

Would it be better to dig out and add additional concrete around the outside of the posts and keep the posts hollow?

Or would it be better to add a 4"x 4" wood post insert and moor it with some interior concrete to moor it?

Or is there another approach?

  • I always use a 4x4 inside of vinyl posts to make sure they stay straight. Also, a six foot wide gate hooked to one post concerns me due to the weight and length. Since I don't how heavy your gate is I can't say how deep I would dig for the 4x4, but three feet, and one eight pound bag of concrete is what I'm guessing would keep the post straight. Also, I'd dig the hole bigger at the bottom for additional support.
    – getterdun
    Jun 17, 2014 at 2:16
  • @getterdun - make it an answer, and I'll accept.
    – Jason
    Jun 17, 2014 at 19:38
  • I'm tempted to suggest two 3' gates. I know that's less convenient for a car, but it avoids putting as long and heavy a lever-arm on the post. Or perhaps put a wheel at the far end of the gate...
    – keshlam
    Oct 3, 2014 at 4:58
  • 1 gate will be fine add a wheel I have a 14 & 16' gates that are heavy a small 6" wheel takes all the weight so no reinforcement of the post is needed. Google gate wheel and I am sure you can find a model that will work with your gate.
    – Ed Beal
    Dec 26, 2017 at 22:36

4 Answers 4


There is always the option to attach a "Wheel" or Roller to the bottom of the gate. The is entirely dependent upon the ground conditions you have. I did this for a vehicle gate at my place. 6' wooden fence, with a 10' wide gate, also wood. Attached a large roller wheel to the gate, and it worked perfectly for years.


Get rid of the concrete, unless maybe, you're dealing with sand, high sand content or arid conditions but those are super easy to go deeper in. I've yet to notice any benefit, at all, to using concrete. It doesn't preserve posts, it's not any stronger, it's not any quicker & it retains & wicks water very much longer.

Yeah, 4x4's are great up to 3' for railings, but even those flex noticeably. I'd suggest a 6x6 or at least a 4x6 if you want the public side kept to scale. The 4x6 would give you the extra beef to minimize door swing sag or bounce along the swinging path.

Of course, screw the 4x6 to the end fence post (which there should be) or screw 2 4x6's to each other at the end of the fence. Vinyl is heavy & a framed gate (which it better be) is really heavy...compared to wood.

  • I disagree the area concrete take up will increase strength, I agree if not properly poured it will accelerate rot.
    – Ed Beal
    Dec 26, 2017 at 22:39
  • That's what I've heard ever since the practice started, but I've never seen it proven nor justified...the concrete holds water longer than the soil, regardless. -- However, if it's poured as part of a driveway or sidewalk, then absolutely! Concrete sealing the post and its entire area will be the only way to go and hugely beneficial. If you're a concrete believer, then you should wrap and cap the post's buried portion with cellophane or a tape before dropping it in.
    – Iggy
    Dec 27, 2017 at 11:54
  • Ever since the practice started? I have been doing this since the 70' s and there were old cresode posts in concrete back then so it is nothing new we would just buy a truck load of cement mix (sand and gravel) and a bag or 2 of Portland cement. 1 scoop cement to 5 scoops of mix and mix it in a wheelbarrow or mixer depending on the size of the job.
    – Ed Beal
    Dec 27, 2017 at 19:47
  • I didn't know about it that far back for DIYers. It started as a failed trend in the early 90's around me.
    – Iggy
    Dec 27, 2017 at 21:15

Dig a 6in. deep trench 4ft. long opposite direction of your gate when closed! Do this against the post revealing some of the post. Fill with concrete and let set then hang your gate! The concrete will be pushing against a larger area creating less pressure against the area of just the post. Like a brace! If you don't want to see the concrete dig deeper to allow for back fill!


I filled the posts of my gates with Sakrete concrete. It's strong enough that when my large gate swings wide enough that single post ends up holding the weight of the entire gate. e.g. the ground level drops a few inches and the wheels lift off.

Just buy a bag of 60lbs Sakrete. Dump it in the post dry and use the hose to add some water. (You can mix if first if you want but this worked just fine for me). Just make sure to also wash away water mix that comes out of the bottom of the post or else it will stain.

However, I am now facing an issue where in high winds my small gate buckled and the steel anchors bent. The hinges on the small gate are all bent out of shape since it bent inward. If I had it to do over again, I'd probably go for two smaller gates instead of one 6' and one 3'.

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