I know lots of installers don't do it, and I personally prefer the unimpeded look, but anything installed outside of the requirements of the material is probably going to be limited, i.e. the insurance company is not going to pay you because the material was not installed according to flooring requirements. 

I have spreadsheets filled with material lists for every phase of the build that includes pricing for materials as well as labor, and sources that I use for them.

And does the person doing the labor get paid or only the materials paid for by the partnership?

all materials, all labor costs to others, Not you, utilities, interest payments, permits, licenses, auto/truck expenses, tools needed are all deductable. 

Think of it as insurance against substandard work or faulty material.

Materials will be about the same, but labor may vary greatly on location.

. $50k sounds like a lot to you but with the price of materials and of qualified labor, it does not go too far.

For example, the iconic Malibu waterfront homes were built directly over the water, many by variance, and assumedly will not be permitted to reconstruct, certainly not with the same materials or attached architecture.

Scope of WorkThe Subcontractor agrees to perform the following work (“Scope of Work”):Detailed description of tasks and responsibilities.Exclusions: [List any exclusions here].Materials to be provided by: [Contractor/Subcontractor].Reference drawings or plans: [Attach if applicable].2.

I have a 10x8 shed that I use exclusively to store real estate materials and supplies.