Laying a concrete garage floor over a drain query

[shd1970]

I am looking to take out the shoddy tarmac/gravel base that currently is my garage floor, and put a nice concrete base down.
Total length of the proposed new concrete floor will be approx 7.3m (front to back)
I have a manhole on my front drive, approx 1.2m forward of where the front of the concrete slab will finish
And finally, my neighbours sink/drain goes into a foul drain in my garden (we are link detached !) and then under my garage floor, into the above mentioned manhole

So, total length from neighbours drain the the manhole is ~ 10.3m in a straight run

I know the foul waste pipe is old clay/porcelain and was encased in concrete so will the building inspector make me take out the old pipe and replace it with a new plastic pipe, due to the weight of the new concrete floor, hardcore and risk of it breaking ?
House was build circa 1960's

We plan to put a sink in the garage too so will need to tap into it somewhere also

Can anyone advise me please ?

thanks in advance

 

[Ian H]

The shared section is really your water boards pipe.

If they are not too deep I'd replace the lot. If they are pretty deep get them CCTV'd before you pour.

 

[tomfe]

Salt glazed pipes are far better than plastic, if it's encased in concrete then you should be alright to poor ontop.
Why have you got building control out?

 

[shd1970]

Salt glazed pipes are far better than plastic, if it's encased in concrete then you should be alright to poor ontop.
Why have you got building control out?

I will actually be bringing the garage door forward and extending the roof also so planning said planning permission and BC would be required

 

[freddiemercurystwin]

If you are building any new foundations in order to extend the garage and any shared drains are less than 3m away your BCO may well expect you to get a Build Over/Near.