House extension on piles - now need access below it...

[EssexAndy]

The extension on the side of my house was built 10 years ago on top of 8 pillars/piles (4 x 2 pattern). I now need to get access to the ground underneath the middle section (drain problem - see my other threads...)

I have explored all other solutions and getting access to the drains beneath the extension is the only answer.

Tunneling is ruled out on Health and Safety grounds, apparently.

This leaves one solution: rip the internal floor up and then attempt to get through the concrete base (a number of concrete beams laid across), to create a ruddy great hole, exposing the manholes. The drain problem could then be addressed. Everything put back - but with access to the drains.

I absolutely know that this isn't straight-forward - but is it possible?
Getting through the concrete beams is one thing, how they would be put back is another.
I'm in no rush but it's a job that has to be done.

 

[Ian H]

What's wrong with the drain?

Just read your drain thread. Most common point of entry would be where the plastic meets the clay depending on how the joints were made.

Are the inside soil pipes accessible? You could CCTV and line from them but if the rats are getting out of the manholes that would be more difficult.

Is the floor block and beam screened over and do you know how big the void is ? I've dug through a couple of them and they were not to bad once the first block was out.

Last thing, have you tried your building insurance?

 

[EssexAndy]

What's wrong with the drain?

Just read your drain thread. Most common point of entry would be where the plastic meets the clay depending on how the joints were made.

Are the inside soil pipes accessible? You could CCTV and line from them but if the rats are getting out of the manholes that would be more difficult.

Is the floor block and beam screened over and do you know how big the void is ? I've dug through a couple of them and they were not to bad once the first block was out.

Last thing, have you tried your building insurance?

Thanks for the reply, Ian.

- The 2 soil pipes run vertically down internal walls and are boxed in. I guess the answer is that they are accessible.

- Only the sections that run the length of the extension have been lined. It is impossible to line the 2 'spurs' that go off at right angles to pick up the 2 soil pipes (which are in the original building)

- Block and Beam would describe the piling, onto which the extension was built. The void looked substantial when they were digging it out but only the tops of the horizontal soil pipes were exposed,which suggests only a couple of feet deep (edited to say probably 2'6" deep possibly 3').

- Building insurance covered the drain lining exercise (through a very dodgy claim company that went bust and screwed the guys who did the work...). I have subsequently spoken to the insurance company but they won't take responsibility for vermin.

The builder who built the extension insists the drains were capped off correctly.

 

[Ian H]

If you could gain access to the soil pipes you can camera down and pull a liner in with a rope.

The contractor would need to pre invert the liner but it is possible.

 

[EssexAndy]

If you could gain access to the soil pipes you can camera down and pull a liner in with a rope.

The contractor would need to pre invert the liner but it is possible.

Not sure I'm with you on this... please humour me.

So I would access the internal soil pipe (at ground level). Such that I could look down a 6" hole in my kitchen floor.
This soil pipe will go down into the floor a couple of feet or so and then turn to be horizontal.
The pipe will then go horizontally for 6' or 7' until it reaches the manhole (which is underneath the extension and can't accessed from above)

Are you saying that it would be possible to pass the liner (in a collapsed state) down the pipe, round the bend and into the manhole. Then pull it back into position?

The guy who completed the drain lining job, after the first lining company got screwed over, is pretty smart. If you think this is possible, I'm sure he could do it.

 

[Ian H]

Yes, he could either 'blow it in' round the rest bend to the manhole or pull it with a rope from the external manhole. He would double up the rope so once in position he can pull it out again.

Blowing it in would be easier and he would use a 'flexi' liner round the rest bend rather than the usual stuff which is 'drag'.


https://www.diynot.com/diy/threads/drainage-engineers-chat-lining-drains.484605/#post-3933906

 

[EssexAndy]

Thanks, that makes sense. I'll give him a call and see what he thinks.
Anything will be better than trying to access the manhole covers.