How to Calculate a Construction Contingency Budget: Guide
A contingency allocation is your primary safeguard against construction cost overruns. We discuss typical buffer percentages, common site surprises, and how to manage your reserve funds.
What Exactly is a Construction Contingency?
A construction contingency is a reserve budget set aside to cover unexpected costs that arise during execution. It is not an allocation for custom upgrades or fancy finishes. Instead, it is a risk mitigation fund designed to handle dry rot, hidden bedrock excavation issues, or sudden supplier material price hikes.
Contingency Allocation Standards: Remodeling vs. New Build
The size of your contingency buffer depends entirely on your project risk profile:
- New Construction: A 5% to 10% contingency is standard. Since you are building from scratch, foundation parameters and design elements are mostly controllable.
- Renovations & Remodeling: A 15% to 20% contingency is highly recommended. Opening up old plaster walls often reveals faulty wiring, outdated plumbing, or structural settling that requires immediate engineering correction.
Best Practices for Allocating and Releasing Contingency Funds
Never give your builders direct access to your contingency reserve. Instead, require them to submit a formal change order request when they hit an unexpected cost. This allows you to verify the takeoff quantities and cross-reference unit rates against your baseline Bill of Quantities before releasing any payments.
Frequently Asked Questions
Between 5% and 10% of the total estimated construction cost is the industry standard for new residential structures.
Often yes, general contractors include a small risk premium in their unit rates. However, owners should maintain an independent contingency fund outside the builder's contract.