How would I value my Company's contracts Backlog?

Hi all. I'm currently having a practical valuation doubt regarding my family's business. We are approaching the negotiation phase with a possible buyer and I wanted to get better prepared regarding value. Our company is an infrastructure EPC and deals with spot contracts and long term contracts.I already did a multiple and DCF analysis to estimate the company value (I have a rough estimate). What I'm trying to do is find the value of our signed contracts (projects that haven't started and are long term projects) in relation to the whole company's value. This way I can argue that this would be the "minimum" value for the company, as I already have signed contracts. I tried studying/searching the internet on reference to value backlog/future contract and didn't find much (damodaran, koller, etc).In theory, I can value any asset calculating the NPV of its cashflow with the appropriate discount rate. That being said, I can't estimate the real NOPAT/FCF of the future project, only Gross revenue and gross income. I would have to give a rough estimate of the change in working capital required for the contract conclusion and I'm estimating that these contract have no capex nor D&A. But these contracts would have a total different margin for a buyer, given new SG&A expense, as example. Is there something wrong with this approach? Should I be doing something different? Any advice is appreciated! via /r/business http://ift.tt/2zL4a9G