If you were not able to run the blower door because of friable asbestos-like-material or possible mold substances in the home, the building leakage should be estimated in ACH, not CFM50.
When estimating the natural leakage in TREAT, use the following qualitative assessments for residential homes: Very Tight: 0.10 ACH, Tight: 0.35 ACH, Average: 0.60 ACH, Leaky: 0.85 ACH, Very Leaky: 1.10 ACH.
If the building shell was not intact, then the blower door number must be considered inadmissible due to abnormal conditions in the house and you should use the ACH estimate.
A fire in the fireplace or woodstove is not sufficient reason to skip the blower door test. Make sure your customer understands to have the fire out on the day of the audit, or you will have to return to the house and re-test prior to approval.