Can you give me an example of a variation that would add to cost and not actually be required for a build?
Any variation. Builder tells you our framer is charging more (when theyre not). You say prove it. They show you a shiny invoice. You ring the framer, the framer says can't discuss commercial information with anyone other than their client. Boom. A variation that added cost without being actually needed. Now replace framer with any other supplier.
It's a losing game to play
Pretty sure they can't do that. It's legit only for structual changes house needs. People need to stand up to these builders. The industry is so corrupt and they bully people. If it's fixed price they can't just add random stuff unless it has the new covid clause in it.
Like I said, this must be your first time. Some builders are smart enough to price this in, others are trying to race to the bottom of the barrel..