In the process of having a conservatory built, the builders digging
out the base have identified that the rainwater pipe to the soakaway
ends in an area that is going to be concreted over. This will then
(apparently, I'm none too familiar with this stuff) result in a new
soakaway having to be dug further down the garden, and the pipework
rerouted into it around the conservatory.

My question is is this something that the surveyor should have
anticipated when the project was specified, or are they likely to want
to charge me extra for it (they've said nothing yet but its only been
discovered this morning, so I'm trying to get some info for when they
do, as I expect, try to charge me extra) . The contract doesn't seem
to make any specific mention either way of reserving the right to
charge me extra for unforeseen problems in the building element of the
job

Thanks for any feedback

Brian