I hope you are mistaken
Here's an example of what I'm talking about. This is the 1983 map that was effective until 2003. Look at the intersection of Wiconsin and 9th, where the Zone is AE 12, BFE = 11'.
Now check out the 2003 map, at the same intersection, the
Zone is AE BFE = 12'.
So they raised the BFE by one foot, while the Datum was adjusted down 0.86' +/-.
A house built at 11.00 NGVD in 1983 would now report 10.14' +/- NAVD, and the new BFE is 12'.
I hope you are mistaken
Or is that UP 0.86?
Or is there more to this than just the datum change? Was there a true map update where different numbers could be expected?
Using the same logic, the values further to the left should have changed also, yet they stayed at 12. Why not 13?
Thanks for the follow up, Steve.
At least he was a gentleman about it.
Rick
I hope you are mistaken
> Or is that UP 0.86?
>
> Or is there more to this than just the datum change? Was there a true map update where different numbers could be expected?
>
> Using the same logic, the values further to the left should have changed also, yet they stayed at 12. Why not 13?
No, it's down 0.86'. I've been dealing with this for 8 years now, so I'm pretty sure I know the direction of the datum change.
But here's the note from the new maps, they use 0.88', which is the county wide average. It's ussually 0.86' in the north parts of this county:
And as for the maps, I think I've been pretty clear from the beginning that the maps under went a complete revision, including new "BFEs" being determinined, and the datum changed. My original point was, when your floor elevation looks to be out of compliance, it doesn't hurt to check the maps in effect when the house was built, because that may explain it.
I hope you are mistaken
You are correct. Sorry for getting confused. Even the wording in the explanation is a bit confusing. The explanation says to go from 29 to88 you add 0.88. Actually the 88 number is 0.88 lower than the 29 number. The illustration helps to make the conversion understandable.