When a builder supplies a blower-door result for an Oklahoma new home, ask for the complete report and confirm the address, test date, units, building volume and applicable target. CFM50 and ACH50 describe different measurements under a test pressure; neither number alone establishes that the house meets every code, certification or indoor-air requirement. Have the tester explain the result and any required correction before using it as a reason to accept the home.
Read the units before comparing the number
Pacific Northwest National Laboratory's enclosure-leakage guide explains that a blower door measures airflow at a specified pressure difference. CFM50 expresses cubic feet per minute at 50 pascals. ACH50 converts the result to air changes per hour using the tested enclosure’s volume: CFM50 multiplied by 60, divided by that volume in cubic feet.
An illustrative calculation is 1,000 CFM50 multiplied by 60 and divided by 20,000 cubic feet, which equals 3 ACH50. This is arithmetic to explain the units, not a pass/fail standard for an Oklahoma home. The pressure is a test condition; it does not mean the home’s air naturally changes three times every hour during everyday occupancy.
Match the report to the completed house
Request the property address, builder identification, test date, tester’s credentials and contact, reported airflow and volume used in the calculation. Ask what stage of construction was tested. If later work altered the enclosure, ask whether that work requires further evaluation or another test. Do not accept a result from the model home as the report for a different address.
Make a small comparison sheet with the report’s house description and the house you are buying. List any unexplained difference for the builder and tester. For example, a missing volume figure prevents a buyer from understanding how the reported ACH50 was derived, even if the final number looks familiar. The useful next step is a documented explanation, not a buyer’s improvised measurement or equipment adjustment.
Ask which requirement the result is meant to satisfy
Ask the builder and applicable building authority which code provisions apply to the permit and ask the certifying professional about any promised program requirements. This guide does not impose one statewide leakage threshold. A contract’s performance promise, the adopted code and a voluntary certification can require different evidence.
ENERGY STAR's inspections and tests guidance describes independent verification and distinguishes blower-door testing from duct testing. Its guidance also explains that sampling may be allowed in some certification circumstances. If a builder advertises certification, ask for the documentation applicable to this specific home rather than assuming a brochure means every test was individually performed at your address.
Our new-home ventilation-controls guide answers what to understand about operating the ventilation equipment. This article addresses how to interpret an enclosure test report. The two records belong in the same home file, but one does not replace the other.
Keep airtightness and ventilation questions separate
Department of Energy whole-house ventilation guidance describes systems that use fans and ducts to exchange indoor and outdoor air. A leakage score does not identify the ventilation equipment, show its settings or demonstrate how an owner should maintain it. Ask for the system’s operating instructions, maintenance needs and the builder’s explanation of how it is intended to work in this house.
Have qualified professionals address safety concerns involving combustion equipment, pressure or ventilation. Do not switch off equipment or block openings to chase a lower test number. The buyer’s role is to obtain intelligible records and the necessary evaluation, not to conduct a hazardous experiment during a walkthrough.
Resolve the report before losing track of the deadline
Put the test report next to the inspection findings and the actual contract deadlines. Ask for any promised repair, explanation or retest in writing, including who will provide the final result. If the answer is that a concern will be handled after closing, discuss the proposed documentation and available options with your transaction professionals before agreeing to that arrangement.
A practical closing packet can contain the final report, any earlier result, the explanation of corrective work and operating instructions. Retain the sequence so a later service professional can understand what was changed. A single photo of a fan in a doorway is useful context, but it does not provide the measurements or conclusions of the report.
Use our OKC metro new-construction guide to coordinate inspections, contracts and the broader purchase. Doug and Ronnie at OKC Metro Group can help keep the questions organized; qualified testers, builders and the relevant authorities determine technical compliance. Reviewed October 21, 2026. Examples here are educational, not certification of a particular home.
