Short answer. No, you didn't screw your client
http://www.fema.gov/library/viewRecord.do?id=1526
You have to use this link to establish tha BFE unless the loacal admin or others already did. I really see nothing above about the elevations.
You said this was based on an estimated BFE, not sure what that is, I wish I could do that around here. Using the est. BFE was the house in or out?
I may be missing something.
Zone A, No BFE and there isn't one on file, so the insurance is based on how the house sits in the ground. The confusion is if it should based on the exiting grade I shot on the backfill or natural grade before the house was built.
This determination was submitted to the building department when the permit was pulled. It's based on the 1983 FIRM.
This is the current 2011 firm.
I reference to your link above, I though that a BFE developed by that method could only be used to develop land and not to rate an insurance policy or support a LOMA.
How did they get a permit to build in the floodway in the first place? Anyone who looked at the map (if they looked at all) would have seen the problem. Will FEMA bend the hazard line to the back of the house?
That manual outlines a couple of methods. The "simplified methods" can not be used for BFEs on elevation certificates. The "detailed methods" can be used for elevation certificates, but are far beyond what I would attempt as a land surveyor.