Screen a Cincinnati spray foam contractor on three things: BPI credentialing (the de facto local standard for building-science training), ICC-ES-evaluated foam products (so the install passes inspection and is documented), and blower-door verification before and after the job (so you can measure what the foam actually achieved). A contractor who can confirm all three in writing is doing the work the way it should be done.
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Spray foam mistakes are expensive to reverse, so the contractor screen matters more than the price quote. Three credentials separate a reliable Cincinnati installer from a one-truck operation. First, BPI credentialing. The Building Performance Institute tests installers on substrate prep, mix-ratio verification, moisture management, combustion safety, and code-compliant installation, not just on operating a spray gun. BPI Building Analyst is the Cincinnati standard; asking whether the lead installer holds it produces an honest yes or no. Second, ICC-ES-evaluated products. Every foam a credentialed installer applies should carry a current ICC-ES product evaluation report, which is the document a building inspector references to confirm the foam meets the IRC for your assembly. A reputable contractor can name the product by manufacturer and provide the ICC-ES report number on the closeout package; verify the number at the ICC-ES site before relying on it for any permit, resale, or rebate filing. Unevaluated foam causes permit problems and often signals a non-credentialed supplier relationship. Third, blower-door verification. A blower door pressurizes the home to 50 Pascals and measures the air-leakage rate in ACH50. A pre-install blower door diagnoses where the foam should go; a post-install blower door documents what the foam achieved (Cincinnati retrofits typically drop from 7-12 ACH50 down to 3-6 ACH50). An installer who owns the fan and runs both passes is verifying the work rather than asking you to take it on faith. Practical Cincinnati screen: ask the contractor to put the BPI credential, the ICC-ES report numbers, the pre-and-post blower-door plan, and the workmanship-warranty terms in writing before you sign. Reputable local installers answer all four without hesitation; a refusal on any one is the signal to keep looking.