11' is not a standard, all studs would have to be field cut, plywood only 8,9 & 10' lengths, drywall is 4' & wide board 4' 6". So you have several factors which will drive the price up on the build of the home by going with 11' ceilings. You can get a 10' pre cut for framing and 10' exterior sheeting for walls, drywall will still require a filler however 10' is a better option than 11'. Is this a CBS block exterior walls?

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We meant in what location, you can search for trustworthy contractors here on Houzz based on your location.

The local contractor working in your area will know all about the extensions permissible by DDA. You just need to match the exteriors with the existing elevation of the building.