Post Hole Concrete

[D45]

Need to buy some bags for my pool deck 4x4 posts

9 total posts

Lots of options and price difference

Mix vs no mix

Fast set vs regular

Suggestions?

 

[Bopbop]

I would use 3000 or 5000 psi mix. The set spend depends on you.
I would google Quikrete concrete. They have some good information on their products and a calculator program to estimate the amount needed.

 

[strutaeng]

I've used "plain Jane" standard concrete mix.

https://www.homedepot.com/p/Quikrete-80-lb-Concrete-Mix-110180/100318511

You'll have to brace each post for 4-6 hours (temperature dependent) for concrete to set. A 2x brace with a stake in 2 directions does it. Brace all posts then mix all the concrete and fill it in. Adjust braces to be plumb. Ideally let set overnight and continue with work the next day.

I've also used the quick setting type and it does speed things up:

https://www.homedepot.com/p/Quikrete-50-lb-Fast-Setting-Concrete-Mix-100450/100318521

I've always mixed it, even though instructions say just dump dry and add water. Brace one post and mix enough for one post. Sets up in like 5 minutes. You can remove brace and go to the next one, but mix one post at a time.

In either case, the curing time is the same, the red bag just sets up faster. Probably don't to start building on top until 24 hours minimum.

 

[Dustball]

For 9 posts, I'd consider buying concrete with the mixing trailer from a local rental company. I've done two jobs of four posts each that required 10-12 bags each hole- the first was done by using a hand loaded mixer and the second was done by buying the ready-mix concrete from a rental company. The rental ready-mix method blew the hand-loading method away for minimal extra cost.

 

[dadsEH]

10 bags to a hole?

 

[D45]

A mixer is overkill and not needed, waste of funds

 

[D45]

The fast setting is a good option, fast set up with less time needed for bracing

Fast setting does cost $2ish more a bag

The posts and concrete will have a week to set up, since o won't have the time to start on the structure

 

[SGKent]

put the posts in sleeves to keep them from rotting. Caulk the tops of the sleeves to keep water out.

 

[b-boy]

put the posts in sleeves to keep them from rotting. Caulk the tops of the sleeves to keep water out.

I agree. It doesn't matter how good your concrete is if the posts just rot at the concrete line.

 

[blkhonda1991]

put the posts in sleeves to keep them from rotting. Caulk the tops of the sleeves to keep water out.

for a deck i wouldnt cast the posts in concrete, pour footings and use post base anchors.

 

[ard]

I wont put wood into the ground or into concrete. I use a post base anchor, something with a stand off AND a serious strap/bolt through connection.

If OP is doing 9 posts and is digging below the frost line, a buggy w a yard of mix might not be a bad idea

 

[danfromsyr]

I've got posts in the ground going on 20years with nary a issue at the concrete/post line.

get properly rated 'ground contact' pressure treated wood.

 

[KANSASBOY]

https://www.inchcalculator.com/post-hole-concrete-calculator/

 

[ford33]

I vote for the concrete base and then use a post base anchor. I have used them on a couple of my decks and prefer them over a post set in concrete.

 

[lilredex]

About 10 years ago a contractor installed these neighbourhood fence posts set in foam. At first I thought it was some kind of a joke, but they are holding up just fine.....checked in on them again this AM.

 

[phenom4hire]

Mix a red bag of quickcrete with two 80 lb bags. It will setup much faster and you can hang on it within an hour or so. I used to build fences for a living and this was my go to method. Dig and set post before lunch, come back after and cut and hand everything else. I just mixed it in a wheelbarrow.

 

[Viper98912]

I used the 80 lb bags of 4000 psi from the local big box store

 

[CKS1955]

5000 psi concrete and rebar. Do not put post in concrete.

Jay

 

[D45]

I went with the normal 5k psi bags

The quick set has a much lower psi and takes 28 days to reach max strength. The quick set is also not structure rated

 

[The Cobbler]

dump the dry mix in the hole. the moisture in the ground cures the concrete .

 

[oldtractors]

I've got posts in the ground going on 20years with nary a issue at the concrete/post line.

get properly rated 'ground contact' pressure treated wood.

You have some time. I just replaced the bottom of 4 posts that were completely rotted off and eventually need to replace the bottom of all the posts in my building that was built in 1976.

 

[D45]

The deck my father built in 1994 had 4x4 sunk into the ground also

Rock solid and no rot

 

[930dreamer]

I have 430 linear feet for one side of my fence to do, just let me know when everyone's available.

 

[TriumphFan]

dump the dry mix in the hole. the moisture in the ground cures the concrete .

Yep, My kids and I built 1,000+ ft. of 4 rail horse fence doing this.

 

[mmb617]

You're getting a lot of differing opinions here, which is what I expected, and everybody probably thinks that their way is the only right way.

Over the years I've sunk an awful lot of 4x4 posts at my place. I'd say 30 or so to build the deck that wraps 3/4 of the way around my pool and 75+ for the fence around the back yard. I'm generally working by myself and not under any real time constraints so I do a couple at a time.

I'm not claiming my way is the only "right" way but simply telling you what I've had good results with.

I use the basic 80# bags of concrete from the box store, currently priced at $4.50/bag, and mix a bag at a time in a wheelbarrow. I find that one bag is about right for one post. I dump that one bag in, let it set then fill the hole the rest of the way with dirt. Some of my fence posts have been up for 40 years.

Don't make the job more complicated than it is. Ready-mix for 9 holes is hardly what I'd call cost effective unless you are physically unable to mix small amounts on your own, and if that's the case you'd probably be better served hiring out the entire job.

 

[brownsmustang]

dump the dry mix in the hole. the moisture in the ground cures the concrete .

This^ I built a lot of pole barns and we never used concrete unless the customer demanded it, then we dumped the bag in the hole.

 

[MushCreek]

I bought a used mixer for $100 on CL. Best $100 I ever spent. If I ever get tired of using it, I can get my $100 back in no time. For my deck, I poured footer pads and set post bases into them. My 6X6 posts are above ground. My deck is 10' off of the ground, and I like to be able to see the entire post instead of learning the hard way that it has rotted off.

The mixer is gonna get busy again soon. I need to pour a walkway out of my basement door, and a set of steps going into the man door in my shop. I'd also like to pour footer pads for a future carport, to also be built out of 6x6's.

Question- Why does every used mixer have concrete left inside of it? It took me 4 hours to clean mine out. When I finish a job, I just hose it out. Why couldn't the previous owner do that?

 

[theoldwizard1]

The deck my father built in 1994 had 4x4 sunk into the ground also

Rock solid and no rot

Concrete is really not required, especially if you are using pressure treated posts.

If you want, pour a 6" "cookie" at the bottom of the hole, let it cure at least overnight. At a minimum, use >6" of tamped (sharp, not round/smooth) gravel in the bottom.

You can back fill with the native soil, just make sure it is tamped in well.


We are talking about a deck, not a foundation for an 8 person hot tub !

 

[D45]

^^^^^^good info, I agree

Especially in my case, the pool deck is only 52" tall

 

[buzzworth]

Wiz has it right. We set 6 x 6 posts for the porch around the cabin, braced them straight and tamped crush&run around them. Haven't moved in 25 years.

 

[ynned]

About 10 years ago a contractor installed these neighbourhood fence posts set in foam. At first I thought it was some kind of a joke, but they are holding up just fine.....checked in on them again this AM.

PennDOT some years ago approved the foam for post mounted signs (possibly R/W fence posts, also, I'm not sure). One of the last jobs I was on the contractor used it. Pretty slick, really; dense, hard, closed cell so water can't infiltrate, cured quickly. No doubt way too much money for the average homeowner, though.
Hell, I'm on the sloppy, wet, clay North Coast, and I think just dirt backfill is fine. The main thing is make sure you get below the frost line, have good bearing on the bottom of the hole (no loose dirt, maybe a flat rock or block on the bottom to spread the weight a little), proper ground contact wood, and decently tamped backfill. It should outlast you by a long shot.

 

[Spareparts]

We put miles of high line with 85' poles along US 24 highway outside Manhatten Ks. in 1978 using close cell foam, still standing. The only problem was the machine we used to mix the chemicals used a small 180 amp Lincoln Welder for power, we lost 3 to thieves. Problem solved when we drilled the mounting holes to 3/4" grade 8 bolts in and welded the nuts.

 

[theoldwizard1]

Wiz has it right. We set 6 x 6 posts for the porch around the cabin, braced them straight and tamped crush&run around them. Haven't moved in 25 years.

And as the person who helped my son remove over 2 dozen 4x4 footing set in concrete from decks that were no longer desired in their location, pulling those lumps of concrete out of the ground is a real PAIN IN THE *** !

Oh, I forgot the additional more than a dozen fence posts. Several were cedar posts that rotted off at the top of the concrete. One corner metal post must have had 2 or 3 bags of concrete in the hole. It must have weighed well over 200 lbs !

 

[D45]

All 9 post holes are done, glad I did them by hand and didn't waste money on renting an auger