The MEP (mechanical, electrical and plumbing) trades are very rarely taken off and estimated in detail by general contractors. If you look at their take off sheets, they will have pages of take offs for concrete but often just a simple square foot cost for the MEP line items. Why do you think this is? Do you think a GC would have a significant competitive advantage in being able to estimate the MEP trades in house instead of just getting assistants from the contractors they have a good relationship with? Its expensive to train estimators on MEP estimating. Is it worth the cost?