N4 Wind Rating

Hey mates, I'm building a two-storey home. The wind rating came back as N4. It's near the mountain area and almost on top of the hill. The neighbor on the right and at the back will be lower. The left neighbor is higher and the one across the street is the same height. I was given an additional cost of $11k. I'm not familiar with this topic and wanted to know if this pricing is within the "normal range". I was told N2 is no additional cost, N3 is plus $5k, and N4 is plus $11k. The details of the required works are below. Thanks!

N4 Wind Classification Upgrades (AS4055-2012) = $11k
- Windows & Doors (External) - fixings & sills
- Font Entry - door frame with no sidelight & sill
- Frame - bracing & tie down
- External - roof sarking & fixings

What do you define as "Normal Range" is your house a Normal House,ie,Flat pad, Std footings, min glass,etc
I suggest you ask for the Structural Engineering Drawings/Details before you commit
$11K sounds a bit "light on" excuse the pun.hth

Thanks for the response. $11k was initially paid for the Site Works. But due to the N4 wind rating an additional $11k was added. Total site costs is now $22k.

I havent seen the structural drawings. Just the description of the 4 addon works for N4 above. I was wondering if this costing is normal or too high?

Wow, wind rating, I've never heard of that before.
(but it makes perfect sense). good luck with it all.