Twyford, wrap-around extension

Drainage diverted after survey, priced in the quote, not discovered later.

The brief: A wrap-around single-storey extension on a 1960s detached house, with a roof lantern over the new kitchen.
Design and planning: The survey found a drain under the footprint. We priced the diversion into the quote, so it was not a surprise later.
On site: Twenty weeks planned, twenty taken. In week nine the clients asked for an extra socket run and a larger lantern.
The money: Quoted £176k, paid £179k. The £3k is the changes they asked for, each priced and signed first.