Has anyone analyzed new construction and how did you do it?

[Lauren Thomas]

We are considering building a brand new triplex and would love a tool to do an analysis.  We have the figures for total cost to build, cost of loans for new construction and the estimated time frame to complete it before we would have renters.  We also know the possible rent amounts and rates for the conversion from a construction loan to a 20 year loan. Also given that it would be a brand new property, we would assume we wouldn't calculate for normal maintenance, and capex for awhile. Of all the great tools on this site, none of them really fit our particular situation. Any suggestions would be greatly appreciated. Thank you in advance!