Construction interest reserve
Model equal monthly draws, equity-first funding and separately funded interest.
Your scenario
Equal monthly project costs, equity spent first, average monthly debt balance. Interest and fees are funded separately and do not compound into the modeled interest-bearing principal. Actual draw timing and capitalized-interest provisions change the reserve.
How the model works
Monthly cost is budget ÷ months. Equity funds project costs first. Monthly interest uses average beginning and ending debt balances.
Worked illustration
For $1.2 million of costs over 12 months with no equity and 12% interest, average-balance interest totals $72,000. Equity-first funding lowers the reserve.
Read the draw convention before using the reserve
This screening model spreads project spending equally over the entered months, applies sponsor project equity first, and charges interest on the average beginning and ending monthly debt balance. Interest and fees are funded separately; they do not increase principal and earn further interest inside the model. The result is appropriate to that stated convention, rather than every construction facility.
Real projects rarely spend at a constant pace. Acquisition costs can occur on day one, long-lead deposits early, and retainage late. Lenders may require pro rata equity, fund reimbursements after inspection, impose limits or exclude costs. An actual monthly cost and funding schedule should replace the linear screen before committing capital.
Separate reserve adequacy from total project funding
Project equity entered here funds costs excluding interest and fees. It cannot exceed that project budget. The reported additional interest and fees need an identified source as well. Calling a reserve part of the loan does not establish that the commitment is large enough to fund it, or that proceeds are available before an invoice is due. Reconcile the complete facility and sponsor cash in sources and uses.
Extend the construction period and raise the rate to test delay. A longer period can increase interest even without a cost overrun. Then add a spending overrun to the project budget and examine whether more equity or commitment is available. Include lease-up carry, operating deficits and permanent-loan conversion conditions outside this construction-only calculation. A project may finish physically while still lacking the income or approvals needed to repay or convert the loan.
What to check before relying on the result
Linear spending and no interest-on-interest. Construction spending is rarely linear; use an actual monthly draw schedule before committing capital.
Model an adverse scenario as well as the expected outcome. Change one assumption at a time to identify what drives the result, then test combinations that could occur together. A property can meet a modeled financial threshold and still fail diligence, legal requirements or lender approval.
Keep the cash-flow definitions consistent
Distinguish recurring property operations from tenant improvements, leasing commissions, capital expenditure, financing costs and entity-level distributions. Verify whether reserves are expenses, funding requirements or cash movements in the documents you are analyzing. A cash-flow convention must remain consistent across the model and the comparison.
Research context
Consult the source material for this topic. The model is an original educational calculation, not a reproduction of a lender’s underwriting system. The initial numbers are hypothetical inputs rather than current market terms. No scenario inputs are transmitted or saved by this calculator.