Thanks, yes similar but different.

A construction bid is on a flat fee paid out in progress payments. Example project bid 100,000 = 4 progress payments of 25,000 each. <- absolutely no revisions or change orders.

Unless there is a change order . You call them (revision) - in construction when a change order happens 3 things can result;

1 - Additional cost paid to the contractor.
2 - A wash wash no cost incurred on both sides.
3 - A credit paid back to a client.

Retainer - in construction only means the fee that the client/owner holds back as finale payment until they are 100% satisfied or willing to sign off on all work.