I think most appraisals are based upon surrounding, similar properties. If so, then there may not be any comparables for the appraiser to use. He is not likely to inflate the value of the house based upon the type of structural componets and insulation.

While you cannot choose an appraiser fro your bank, you have a right to an appraiser who understands your construction. If he doesn't, complain to the bank & have them find one who does. In my experience with banks appraising double wall construction, the "cost" appraisal was right on the money - aided by my cost breakdown of the components - but the "comps" - the comparison to previously sold houses, was low, since there are no similar comps for sale. Bottom line, you may have to come up with additional cash to get your loan.

An option, should you need or want one, is to find a less expensive way to achieve the same thing - i.e." double wall construction or some other type.