Renovation Overrun Buffer Calculator

Build a transparent renovation reserve from expected change orders, unknown-condition allowance, price escalation and schedule carry costs.

Quick answer

Renovation Overrun Buffer Calculator

Instead of choosing one arbitrary contingency percentage, this tool shows the separate risks that make up the buffer you want to carry.

Formula: Recommended modeled buffer = expected change orders + unknown-condition reserve + escalation reserve + delay carry.

Base renovation contract / budget ($)Budget before the modeled overrun reserve.Expected change ordersYour own expected count.Average change order ($)Average cost per modeled change order.Unknown-condition allowance (%)Reserve percentage for hidden conditions or scope uncertainty.Price escalation allowance (%)Material/labor escalation reserve as your own percentage.Possible delay (months)Schedule delay you want to budget for.Delay carry cost per month ($)Temporary housing, storage, financing or other monthly carry cost.

Enter your numbers and calculate.

How the calculation works

Recommended modeled buffer = expected change orders + unknown-condition reserve + escalation reserve + delay carry.

Every rate, percentage, cost and value assumption shown in the calculator can be changed. Results are scenario math based on your inputs, not quotes, appraisals, code determinations or predictions.

Questions people ask

Is this the same as adding 10% contingency?

Not exactly. It itemizes change orders, unknown conditions, escalation and delay costs so you can see what is driving the reserve.

Are the risk percentages recommended by the site?

No. They are your scenario inputs.

Can I use this after I already have a contractor quote?

Yes. Enter the base contract and then layer the risks you want to model.