Coop Building on a high water table

[Janeofalltrades]

Does anyone have experience building on a high water table? I need secure posts into the ground for the exterior of my run but am in the water table when I dig down a foot and a half or so. I plan on pouring quickrete around the base of the posts (I have pressure treated 6x 6's). Someone recommended a wide quickrete base since i can go down much more than a foot; does anyone have a similar situation or recommendations? I live in a dry mountain climate so the ground of the run staying dry isn't a concern.

 

[cavemanrich]

If you are digging 1 ½ feet, and are reaching water,, Here is my suggestion. Dig down as deep as needed to steady your posts. Yes there will be water in that hole, as you are removing the soil. So lets assume you reached your desired depth. 2 feet,,,,, 3 feet Take your post, and treat the earth depth portion with roofing tar. (brush it on or dip into bucket and brush up.) Treated lumber is not as good as it used to be before. It still is green tinted, but not very resistant to rot as previously. Mostly just resistant to insect damage.
Try to remove most of the water out of the hole. Drop some dry concrete mix into bottom of hole. Then set your post on top of that layer. Then Position your post straight and plumb, and secure into place with whatever bracing works for you. Fill the hole with dry concrete mix to just above the water line level. Pound down tightly all around your post. (meaning pack the dry concrete mix tight.) The water will wet the concrete on its own. Next day, fill to top with wet concrete, and you have a well set post.
I am wondering why you are using 6 x 6 lumber. It seems an Overkill. Of course I don't know exactly what your plans are.
Ask anything else you are not sure of. I tried to explain as well as possible, but sometimes things do need some further explanation.

WISHING YOU BEST,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,and

 

[mowin]

I wouldn't use concrete. Treat the end that will be underground, and use gravel to set the pole.

 

[Janeofalltrades]

If you are digging 1 ½ feet, and are reaching water,, Here is my suggestion. Dig down as deep as needed to steady your posts. Yes there will be water in that hole, as you are removing the soil. So lets assume you reached your desired depth. 2 feet,,,,, 3 feet Take your post, and treat the earth depth portion with roofing tar. (brush it on or dip into bucket and brush up.) Treated lumber is not as good as it used to be before. It still is green tinted, but not very resistant to rot as previously. Mostly just resistant to insect damage.
Try to remove most of the water out of the hole. Drop some dry concrete mix into bottom of hole. Then set your post on top of that layer. Then Position your post straight and plumb, and secure into place with whatever bracing works for you. Fill the hole with dry concrete mix to just above the water line level. Pound down tightly all around your post. (meaning pack the dry concrete mix tight.) The water will wet the concrete on its own. Next day, fill to top with wet concrete, and you have a well set post.
I am wondering why you are using 6 x 6 lumber. It seems an Overkill. Of course I don't know exactly what your plans are.
Ask anything else you are not sure of. I tried to explain as well as possible, but sometimes things do need some further explanation.

WISHING YOU BEST,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,and

Thanks for the advice! Im using 6 x 6's because I have them on hand and was trying to avoid buying more lumber. I thought it was overkill too but then thought they might even be stronger? thoughts?
I did want to treat the end that goes in the ground, think RubbrCoat 57 would do?

 

[Janeofalltrades]

I wouldn't use concrete. Treat the end that will be underground, and use gravel to set the pole.

Any thoughts on RubbrCoat57 to seal the end in the ground?

 

[mowin]

Any thoughts on RubbrCoat57 to seal the end in the ground?

I've never used it, but it should work.

 

[U_Stormcrow]

Black jack and rubbercoat are both fine for treating the earth end.

When I lived in daytona beach (ok, right outside daytona beach - was cheaper), water table was the same. We took our shovel, post hole diggers, whatever, made a nice deep hole. Yes, past water.

Set a 5 gallon bucket in the hole. Stuck our post in the bucket, and poured concrete around that. Just enough to get the bucket to sink. We want it so that the lower rim is level with the ground. And level across the top of course.

Throw mud back at the sides the bucket, rock things around a bit till the bucket is good and settled, good and level, and you have mud up roughly to the water line. True up your post (this is part of why you didn't fill the bucket to the top!) and set your temporary braces.

Prepare to concrete in as normal, BE CERTAIN to "crown your pour". If you want extra "insurance", black jack (rubbercoat, even some latex paint!) the post in a ring at the level of the crown before you pack your concrete in. No need to do the whole post, just the piont where water will sit at the line where concrete and wood contract and a couple inches in either direction.

Concrete things in, and let it cure. Plan on one 80# bag per bucket. You will have extra, you don't need a steep crown - throw the excess into the mud around the next bucket, probably 10-15#?

As soon as its pretty dang hard, but long before its fully cured, paint/blackjack/etc the whole top. Rot will NOT be an issue. You will get a nice strong cure, and you have a clean edge for the string trimmer from the bucket. When it finally breaks way, you will have a nice concrete pylon - but until then, water intrusion thru the concrete won't be an issue.
If for some reason you aren't doing an elevated build, use the same process, but cut the bottom out of the bucket and invert it, driving it down to ground level. Set that into your hole and fill with concrete. Set your J-bolt to depth with washer and nut. Paint the top with blackjack and install your timber bracket (4x4 or 6x6, whichever you need) after the crete has partially cured.

 

[cavemanrich]

Thanks for the advice! Im using 6 x 6's because I have them on hand and was trying to avoid buying more lumber. I thought it was overkill too but then thought they might even be stronger? thoughts?
I did want to treat the end that goes in the ground, think RubbrCoat 57 would do?

I understand your point now,,, Use what you have..
The rubber coat 57 will work just fine, if you have some on hand. I just suggested tar, because it is GOOD,, and less pricey than other products. You can get away using paint,, (few coats) if you are doing on a budget, and want to use up old paint in your possession. Save cash for better more important items. Your paint will need to dry, whereas tar could be put into hole, and cemented while still wet.

 

[Janeofalltrades]

Black jack and rubbercoat are both fine for treating the earth end.

When I lived in daytona beach (ok, right outside daytona beach - was cheaper), water table was the same. We took our shovel, post hole diggers, whatever, made a nice deep hole. Yes, past water.

Set a 5 gallon bucket in the hole. Stuck our post in the bucket, and poured concrete around that. Just enough to get the bucket to sink. We want it so that the lower rim is level with the ground. And level across the top of course.

Throw mud back at the sides the bucket, rock things around a bit till the bucket is good and settled, good and level, and you have mud up roughly to the water line. True up your post (this is part of why you didn't fill the bucket to the top!) and set your temporary braces.

Prepare to concrete in as normal, BE CERTAIN to "crown your pour". If you want extra "insurance", black jack (rubbercoat, even some latex paint!) the post in a ring at the level of the crown before you pack your concrete in. No need to do the whole post, just the piont where water will sit at the line where concrete and wood contract and a couple inches in either direction.

Concrete things in, and let it cure. Plan on one 80# bag per bucket. You will have extra, you don't need a steep crown - throw the excess into the mud around the next bucket, probably 10-15#?

As soon as its pretty dang hard, but long before its fully cured, paint/blackjack/etc the whole top. Rot will NOT be an issue. You will get a nice strong cure, and you have a clean edge for the string trimmer from the bucket. When it finally breaks way, you will have a nice concrete pylon - but until then, water intrusion thru the concrete won't be an issue.
If for some reason you aren't doing an elevated build, use the same process, but cut the bottom out of the bucket and invert it, driving it down to ground level. Set that into your hole and fill with concrete. Set your J-bolt to depth with washer and nut. Paint the top with blackjack and install your timber bracket (4x4 or 6x6, whichever you need) after the crete has partially cured.

This whole explanation is AWESOME. I can not thank you enough. the coop is on a slight downslope so one of the posts will not be elevated... since I'm cutting a hole in the bottom of the bucket does it just stay in the ground forever?

 

[U_Stormcrow]

This whole explanation is AWESOME. I can not thank you enough. the coop is on a slight downslope so one of the posts will not be elevated... since I'm cutting a hole in the bottom of the bucket does it just stay in the ground forever?

Yes, yes it does. Well, eventually it breaks down, but protected from UV it takes "a while".