Barn Project - post holes filled with water

[PhilVA]

I'm in the planning stages of a 36 x 60 barn. I know of one issue I'll have but not sure how much concern I should have about it. I know when I use the PHD for the poles , they will fill about halfway with water. I know this because I built a run-in shed very near the spot for the barn and some of those post holes filled with some water. For the run-in I was able to pour in several bags of quickrete around the poles and the run-in is as solid as it can be.

I'm concerned that the water-filled holes will not be good for the poles in the long run. I'm concerned they will rot. I have the same concern about the poles in the run-in shed but it would cost considerably less to replace it versus the barn should something go wrong. The soil here is a mix of sand and clay.

Any comments would be welcome and appreciated.

 

[EddieWalker]

Peasure treeted posts used as boat docks last for a very long time in the water. Of course, they will need replacing in time, and this is probably your concern.

Could you fill in your post holes with concrete and rebar with a bracket set in the form to bolt on your posts above grade?

 

[wroughtn_harv]

Home Depot and Lowes carry sonotubes. They're cardboard tube forms for concrete.

I'd drill my holes. Wedge down the sonotubes. Pump out the water with a small pump. If the water's coming up from the bottom I'd pick up some Quick Rok or equivalent like Pour Stone. That's a hydraulic cement and will set up under water. You don't need much. Just enough to seal the bottom until you can get the concrete poured.

Commercial pier drillers will run though layers of water. They put in casing to keep the water out. Then as they pour concrete they lift out the casing.

You don't have to lift out the Sonotube as you pour. But you really don't water in your concrete.

 

[Tevi]

Use a multi layer 1x for your posts and wood won't rot under water.If you have that much water I would consider a spread footer

 

[have_blue]

Concrete sets up just fine under water. A little concrete under the post will protect it from water. Maybe just empty the hole, pour dry concrete mix about 2 inches deep in the hole, put in the post, and finish filling the hole with dry mix. Over filling the hole and rounding it off will help it shed rain. Whatever you do, avoid a "cup" of "funnel"around the posts that hold water.

 

[oliver28472]

There is a shop forum on agricultureonline. Recently there was a question about how to replace rotted posts. One reply mentioned something called perma column and gave a phone number and website. Might be a good solution.

 

[rmlucasco]

16" precast "biscuts" are normally used when there's a high water table. You can backfill with dry conrete mix if you wish but the portion of the pole below the table will still be wet. If, many years in the future, you need to replace a pole, that concrete will be an issue. I'd skip it

 

[drm]

Placing concrete under water and achieving a good quality pier is difficult. Just dumping dry concrete mix into a water filled hole is not a good idea since you can not control the amount of water mixing with the cement mix. Too much water mixed in with the cement will create a concrete which most likely will cause you problems.

As for the water's effect on the posts, use treated posts intended for piling (for docks). Wood that is always wet will not rot or decay in normal clean water. Wood that is always dry likewise will not rot which is why we coat & treat decks, siding, etc. The problem is when the wood gets wet then dries repeatedly. Unless the water level never changes, the posts will deteriorate over time if you place them in the holes. You can only hope to slow down the deterioration. I have seen 30 year old pole buildings that are doing fine.

I am assuming that the holes are filling with water due to your water table being above the bottom of the posts. Depending on the amount of sand and how porous the soils is, you may be able to block the infiltration of water while placing the concrete. I would use a 4,000 psi concrete mix and allow at least 6” of concrete around the post if you place the posts in the ground (a 20” diameter pier would be required for a 6x6 post placed exactly in the center). A better solution is to place the concrete piers without the post embedded. Attach a post anchor to the top of the pier and attach the post to it. This method of construction will not provide you with the rigidity of a post embedded in concrete but will eliminate the water rot problem. You may need to modify your design if you are building a typical pole building or post & frame building because of this.

 

[have_blue]

DRM,

I have set many posts with tamped dry mix, and have had to remove a few and salvage the posts. You wouldn't believe how hard you have to hit it with a sledgehammer to break it. Tamped dry mix with crushed gravel has a compressive strength nearly as high as the cured product.

I can understand concrete being weak if you keep working overly wet mix until it partially sets. But undisturbed, the excess water rises to the top. This makes a real mess on a slab, but post holes are fine.

 

[rambler]

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This is what I was thinking, and the direction I would go. They have a web site showing what it is. I believe I remember they sell direct, or also through Wicks Building.

Making your own concrete piling would also work.

I would be real concerned about any wood down there. Unless you can get the ocean peer type of treatment, you gonna have problems. Not actually with the wood under water, but that zone where the water & air meet - that will rot away quickly on you. Dug up, you will find almost new wood where it is totally submerged.

Also, I would wonder about load bearing of your poles. Will a normal pole footer support your building? Someone mentioned spread footer - I would worry about this as well.

--->Paul

 

[JD3130]

What kind of floor are you going to have in this barn? Gravel, Concrete? Dirt? I have to agree that the best method to deal with a water table so high, is to pour a good footing and attach your poles above ground.
Some years back, when my Dad had his dock built, they drilled and installed 16" tubes, installed the rebar cage, poured the concrete into the tubes. they didn't pump out the water. The concrete was damp enough to displace the water. They used vibrators to get any trapped air out. Foreman told me it would set up just as hard as any other concrete. He said that such a little water mixed in, that they could even do it in salt water? You might check with some dock workers to see if they use a special mix. I guessing they use a 6 bag mix.
Are you going to have to worry about your equipment flooding during the rainy season? /forums/images/graemlins/frown.gif
Good luck

 

[keeney]

Building my house during the rainiest summer we ever had, all my porch footing holes were full of water the day they wanted to pour.

The concrete guys pulled the mucky few inches of clay at the bottom out of the holes with post-hole diggers. Then they just poured the concrete in without pumping out the water. The excess water floated out the top and did not significantly mix with the concrete.

- Rick