On new construction, the right time to lock is when your closing date becomes reliable — and the right tool is usually an extended lock designed for builds, not a standard lock stretched past its limits. Because completion dates move, rate lock strategy on a new build is about managing the gap between "contract signed" and "keys in hand," which can be several months or more.
Why new construction breaks the standard lock
A standard rate lock covers the window between application and closing on a typical resale purchase. New builds regularly outlast that window — weather, permitting, labor, and materials all move completion dates. Lock too early with a standard lock and it expires before the drywall is up; wait for completion and you carry months of uncertainty.
This is a structural difference between new builds and resales, one of several we cover in new build vs. existing home mortgages.
The tools: extended locks, extensions, float-downs
Lenders that do serious new construction volume offer lock structures built for it:
- Extended locks: lock periods measured in months rather than weeks, designed to reach a build's completion date. They typically involve an up-front commitment and cost more than standard locks — the price of certainty over a longer window.
- Lock extensions: if the build runs past your lock, extensions add time, usually for a fee that scales with the added days. Repeated short extensions can cost more than one honest extended lock chosen up front.
- Float-down options: some extended locks include a one-time option to adjust to current terms before closing if the market has improved. The mechanics, windows, and eligibility rules vary by lender — ask exactly how and when it can be exercised.
When to start the lock conversation
Before you sign the purchase contract, not after. The builder's estimated completion date, the contract's treatment of delays, and your lender's lock menu need to line up. Three questions frame the decision:
- How reliable is this builder's completion estimate? Ask the sales office for their recent actual-vs-estimated record and pad accordingly.
- What lock periods does my lender offer, and what does each cost in fees or pricing? (Compare structures, not predictions.)
- What happens at expiration — what do extensions cost, and is there a worst-case plan if the build runs very long?
Locking on a construction-to-permanent loan
On a construction-to-permanent loan, the permanent phase terms are typically set at the original closing — before construction starts. That is the one-time-close advantage: the long build happens inside a loan whose permanent terms are already established. Some CP programs also offer a modification or float-down window at conversion; ask whether yours does and what it costs.
On builder-financed production homes, you are closer to a normal purchase lock, just with a squishier closing date — which is where extended locks and the builder's completion track record matter most.
Timing traps to avoid
The recurring mistakes we see on new construction locks:
- Locking a standard short lock on a home that is months from completion, then paying extension after extension.
- Treating a builder incentive tied to their lender as a reason to skip comparing lock structures — the lock terms are part of the offer. See builder preferred lenders.
- Forgetting that re-verification happens near closing: new debt during the build can cost you the approval no matter what your lock says.
- Never asking about float-down mechanics until after locking — the option only helps if you know its rules.
Frequently Asked Questions
When should I lock my rate on a new construction home?
When your completion date becomes reliable enough that a lock period can realistically reach it — often when the build is far enough along that the builder can commit to a closing month. For longer horizons, extended locks designed for construction are the purpose-built tool.
What happens if my home isn't finished when the lock expires?
You extend the lock, typically for a fee based on the added time, or in the worst case re-lock at current terms. Discuss extension costs and the worst-case plan with your lender before locking, so a delay is an inconvenience rather than a surprise.
What is a float-down option?
A feature on some extended locks that lets you adjust to improved market terms once before closing, within defined rules. Availability, windows, and costs vary by lender and program — ask for the exact mechanics in writing before you rely on it.
Are extended rate locks worth the cost?
They are insurance: you pay for certainty over a long, movable timeline. Whether that trade makes sense depends on your build length, your budget's sensitivity to change, and the builder's track record on completion dates. Compare the extended-lock cost against realistic extension scenarios.
Planning a new construction purchase?
The Cook Brothers Mortgage Team finances new builds every day — for buyers and for builders. Get straight answers on your scenario.
Talk to Our Team