I have done many proposed new construction appraisals on a 2055, a Limited Appraisal / Summary Report, for PNC, Washington Mutual, and other lenders.
You must have the plans & specs, but you do not have to do a cost approach if departure has been "properly" invoked. Having the plans & specs is what makes it an 'interior' inspection. You are inspecting the interior by analyzing the plans and specs. You can't do an appraisal on a proposed construction without plans and specs.
The cost approach is one of the biggest bunch of BS going. One thing my Daddy taught me growing up in agriculture was "it doesn't matter what somthing costs, it only matters what it will bring when you get ready to sell it." It doesn't matter if it is cattle, a tractor, a tandem disk, a truck, land, or a house or a hay crop. I know there are some great beleivers in the cost approach, and I know there are rare times when it is the most applicable approach. I have weighted appraisals to the cost approach before, but I don't like it.
If you want to do a cost approach and put it in the file, couldn't hurt, I don't do it.
BB in Texas