Tutorial: How to Model a Real Estate Development Construction Loan

Let's not forget that mezz can also fund pari passu with the senior. It's not as common, but it happens for good deals and/or good sponsors. I would advise building this switch into your model. For pari passu funding, instead of funding all the mezz first, you just have to adjust the formula for the mezz draw down by multiplying the mezz/senior split to the draw and it should flow down to the senior draw line (which should just be the difference between the costs at that period and the equity and mezz draws above it).

As for the interest, I personally have two separate sections on the cash flow tab - one for senior loan cash flows and one for mezz. In these sections you can calculate the beginning and ending balance (as a function of draws and paydowns as well as accrued interest if it is added to the principal), interest rate based on spread and LIBOR (both for current and accrued interest) and the resulting interest payments.