High water table and digging a coop foundation-Help!

[humboldtpeeps]

Hi, started our coop today!
well, to be honest- we move like snails - we only got as far as laying out the foundation for the coop/run frame.
We live in coastal humboldt county and the water table where we live is really high. we have had lots of continuous rain lately (5 inches so far in march i hear) and even though the coop/run area is in good shape the rest of our yard has standing water in places. it was a mud bath!
We are using pier blocks with wood inserts for our foundation and have laid them out at 3' intervals , buried with the tops extending about 2 inches above the ground and will build the frame on top of those. Our coop will be elevated.

Here is the concern:
As soon as we started digging our holes, they began to fill up with water- you know, like digging at the beach...
I am baffled as far as what to do next- I am not a builder by any means so i thought id ask if this was a big problem?

Anyway, we threw some sand in and made a nice wet "cement like" consistency and leveled them all out they seemed pretty solid. We are getting continuous rain for the next 10 days (that's as far the forecast will predict - so who knows, could go on forever

) and im worried what more rain + then drying out will do to our frame/foundation- will it move, warp or buckle?
is there anything we can do to mitigate this?
We don't want to pour concrete (its a rental). Would gravel help in this situation?

 

[Huskeriowa]

Hi,

I am assuming you are using treated lumber for the legs of the coop? If so yes it will warp and crack but if it has a rating of at least .40 then you should be fine for a long time for any type of rotting issues if rotting is any concern to you. If the pier you are setting the post in continues to stay wet then you can always go to a higher end lumber yard. The will likely carry a rubber membrane specifically made to wrap the bottom of posts so they don't get wet. Its pricey but in some situations worth it. I don't think stores like Home Depot and Lowe's wouldn't carry the product.

Yes gravel under your piers might help. I have seen contractors in this area put gravel under their deck posts if the water table is high or if the location of the posts are in a low part of the yard.

 

[Royd]

Are these pier blocks the standard HD model, about 8" high, which will accomodate a 4x4 post or a 2x board...If so, you are basically setting them at ground height.
If ground water is a regular problem, I'd be concerned about the coop being only inches off the ground. Of course, I'm not a fan of buildings sitting so low that I can't crawl under them, if an animal dies or if a chicken decides to build a nest under there.

I know it would be considerably more work and cost, but I'd build some pyrimidal slip forms and then, make a solid base of gravel, say a foot in the ground, and pour the piers.... For a building 20x20 you'd only need 9 piers to support your foundation timbers...You could build 3 slipforms and pour your piers in three days. Cheaper and less involved than building 9 forms.

 

[patandchickens]

Quote:
I would recommend rethinking this. YOu are going to have rot and rodent problems with so little clearance.

Since you seem to have wet soil

I would STRONGLY suggest instead getting four 12x12 (or larger) concrete pavers -- good thick ones, or stack two (meaning, use 8 total) and set a pier block ON each one of them. This will result in much better resistance to sinking into the ground, AND more clearance under the coop (still minimal, but a whole lot better)

Good luck, have fun,

Pat

 

[humboldtpeeps]

This is what we are basing our plan off of- http://www.thegardencoop.com/
The coop itself is elevated to about 2.5 feet off of the ground, with a run area underneath and around for a total of 5' x 10'. what we buried were some concrete pier blocks that have a square of 4"x4" pressure treated wood in the center that we can anchor the floor pan of the frame to it so that framing of the run will be 2+ inches off the soggy ground. We filled the edges with gravel and are hoping it works- here is a link to my friends picture of what we did: http://www.facebook.com/#!/photo.ph...7&set=a.497863777126.270468.678007126&theater (let me know if this doesnt work and ill put it in photobucket.
the base will be pressure treated wood.

We have gotten an extraordinary amount of rain! its like a swamp. its unbelievable!

 

[2DogsCoop]

If you are using PT 4X4 then you will be okay. As long they feel firm then you should be good. I wouldn't put to much weight on them until the ground starts to firm up though. But that is me and I am in no way a carpenter.

 

[patandchickens]

Quote:
Oh ok, that should be ok then!

It would still be better to use pier blocks atop large pavers; but it sounds like it does not really MATTER a whole lot if things sink down a bit, so I would not anticipate major problems with the way you've done it either, as long as you've used large p/t lumber (preferably the kind rated for ground contact -- I don't know for sure about the new ACQ p/t lumber, but the old CCA used to come in different grades of how much preservative was pumped into it, and for ground contact you needed to specifically purchase a higher-treated grade).

Good luck, have fun,

Pat