Book contractors use for estimates

[Anonymous]

Does anyone know the book or other guidance that contractors use to help them make bids?

[Anonymous]

https://www.rsmeans.com

The only sector that tends to use data like this is commercial or institutional construction, the guy putting your addition on is not subscribing to this. Contractors costs vary widely because each will have a completely different business set up, most estimates are derived from personal experience, material costs, estimated labor costs and mark up which will fluctuate with demand.