How To Select A Commercial Contractor
Can the company show proof of NADCA membership and certification?

How long has the contractor been in the residential HVAC system cleaning business?
Can the contractor provide you with evidence of the current Worker’s Compensation and General Liability Insurance coverage? (Ask for Certificate of Insurance)
Does the contractor posses the proper Licenses that are required by your city or state to perform the work they are proposing? (Not all cities or states require licenses - click here to check your state.)
Can the contractor provide you with 3 to 5 customer references with phone numbers for projects of similar size and scope of work which they provided service in the last year?
Does the contractor have written safety, respiratory, and confined space programs in addition to OSHA compliance reports?
Will the contractor provide you with a means to conduct a visual inspection at any time during the cleaning? (Mirror and flashlight, camera or other remote visual systems)
Will the contracting company actually do the work? (Some companies subcontract the work to independent contractors. You will want to apply these guidelines for subcontractors as well.)
Will the company be assigning an Air Systems Cleaning Specialist (ASCS) to your project that will be responsible for the complete project?
If there is any remediation of mold or other biological contamination does the company have a Ventilation System Mold Remediator (VSMR) on staff.