My wife says when you form a partnership you should include terms for breaking up.
When I hire a licensed tradesperson ...
I use a contract that says everything that is engineered is to be installed according to the engineering. Everything that is not engineered is to be installed according to code. Everything else is in accordance to the plans. Everyone posts a performance bond.
For HVAC, electrical, and plumbing:
All holes and notches in any member will be engineered by my engineer and made by my carpenter. Any holes or notches in any members not engineered by my engineer or not made by my carpenter will be repaired by replacing the member. The replacement will be done by my carpenter under the direction of my engineer. Their usual hourly rates will be charged and the HVAC/electricl/plumbing contractor will pay the cost for the repair and any delay related costs.
-----
If you know the workers, no contract should be necessary. If you don't know the workers, no contract is enough.
