Whats the best way of getting thru 2ft thk x 3 ft deep concrete

I am a rank newbie but think it might help if you could say what sort of posts you wish to use - eg concrete or wood? height? And also how many?

Realistically you're not going to be able to site posts in a concerete slab like that. One way might be to use angles steels to fix the pot to the existing concrete.

If it's that strong, and on the line of your new fence, can you leave it in place, drill it and rawlbolt brackets to it to take your new posts?

These maybe?

On Sat, 17 Feb 2007 15:11:57 -0000, "Autolycus" mused:

That was my first thought.

If you really want to move it, get a mini digger with breaker attachment. Loads of fun. ;)

If the top of concrete near or above the ground level then you could bolt on steel post sockets. You'll need an SDS drill to make the holes for expanding fixing bolts.

DIY thermic lance?

Depends what arrangement you want. Others have suggested bolt-down post holders - the only easy alternative is to go for a concrete drilling specialist - but you'll probably only get a 6" hole, and that'll cost an arm and a leg...... :-(

I'd get some post sockets with holding down brackets made up by a local engineers (shouldn't be expensive) and bolt them to the top of the beam with Multi-Monti concrete screws. Fix them down with an SDS drill and then just insert your posts and nail or screw them in. If they are concrete posts, I'd drop them in and then use a fast setting pour in grout.

I'd forget any thought of coring or drilling pockets in the beam.

In message , luke58 writes

I suppose there is no chance this is something important: sewage or surface water duct?

A modest housing estate was built on an old chemical works next to my boundary fence. Concrete piling was used to avoid disturbing the contaminated soil and a large concrete duct installed to collect rainwater prior to it being pumped through a reed bed filtration system.

In order to provide a reasonable fall the duct (6'x6' and 300' long) was very close to the surface at the downhill end.

regards

Drill some holes about 11mm dia.. glue some rebar in.. cast the posts in situ using shuttering.

Invite local terrorist cell to practise bombing,after their last effort they need it

Hire a diamond core drill rig

All the ideas about mounting your posts to the concrete seem very sensible. However if you want to actually get rid of the concrete, the engineering solution would seem to be appropriate - get a bigger hammer. 4lb hammer + chisel does nothing compared to a big whack with a 10lb sledge.

cheers, clive

How much is an arm and a leg ??

The wife wants concrete posts, so I will have to forget the bolt down methods. To be honest they are useless below ground level, as they rust badly