Hi All

Finally got round to digging out my footings, the orginal plan was to dig out a area of 2m by 1m by 1m deep for my pier's however once I got to a depth of 18" the hole stared to fill up with water. It looks at though this is the level of the water table.

Anyone have any suggestions? Is 18" deep enough for pier foundations?

Cheers Jon

The depth is probably ok, if in doubt make the hole wider to counteract any over turning moments....

That would be your winter water table - in the summer, assuming it is dry, it will be quite a bit lower. By the way - if you are concreting - wait for the warmer weather. Concrete does not like temps below about 5 deg C when setting. Colder can wreck it especially if it freezes!!! Seriously bad news if you have to dig it all out because the ice has cracked it up.

What bizbuilder said
My mount is set in a 2 foot by 3 foot cube but I'm lucky that my underlying foundation is boulder clay which Im told is pretty stable and doesn't move around much, for good measure I hammered in lots of steel bar at different angles before I poured the concrete.

Don't listen to the Americans and their multi tonnage cubes.....its just not needed

Yep, my pier foundation is about the same as George's...

And mine... I used three 5 foot lengths of 2" x 1/4" thick angle driven into the ground at angles with the tops crossing in the concetre block...mainly because I was on "made up" ground about 10 feet above "natural"


Billy...

Thanks for the advice, im located in the fens, so water is not too far away what ever the time of year

cheers Jon

Jon.
My No 2 pier dig, struck Clay just under 2 feet down.
I bought one of those steel post holders, that taper down to nothing. They are about 3 foot long, and I smacked one of those down in the hole centre, leaving about a foot protruding above ground. I placed the pier over the stake, and filled the hole with crete, and the pier too. Prior to filling though, I put conduit up through the pier and also waste pipe. These led underground to where the puter sits in the warm room bit. A draw tape in each pipe for drawing cables through. Brace the pier in a vertical position, and wait a few days for the crete to set sufficiently.
Most of this is as you would do it anyway.
Don't forget the piccies mate. We like to see what progress
is made..
Ron.

Out of interest, this month's S@N has an article about setting up an external pier - could be helpful?

As to the water table, it's going to be much higher than usual at the mo - all that metling snow and most of it melted by heavy rain is just making it higher and higher. Pity all those people without tanking in their cellars!

Remember that concrete will set underwater. It will be weakened, but I doubt that would be an issue for pier foundations.

Just watch for washout...

-Concrete Engineering general discussion - Pouring under water

Billy...

I was wondering if half the Concrete in water really mattered..whats the possibility of water seeping back up through when the concrete has set during pier use?
I know the Romans could set concrete in the sea...aahh um anyway look forward to seeing your pics.

I suppose you could pour into a Heavy duty plastic bag to minimise the risk of washout...

Billy..

I thought concrete got stronger if in contact with water as the curing process is slowed down. Concrete continues to gain strength over a prolonged period of time after the initial setting period of 28 days. Bail out as much water as possible then just empty a good few bags of dry post-crete in the hole, position the pier and your away. Don't worry too much about the water, you'll have a concrete pad as hard as steel

As long as you stop washout yes...

May thanks everyone, your advice is much appreciated as always.

cheers Jon