Craig,
If it is a condo:No
If it is a regular townhouse or in a PUD, then YES, you need to complete a Cost Approach. You do not have to complete the VC sheets or Homebuyer's Summary Form for proposed or under construction units.
Now, the kicker is if the CO has been issued. If the unit is complete and the CO has been issued, it is considered existing and you will have to do the Cost Approach, plus the VC Sheets and the HBS, just as you would in a regular FHA appraisal.
If there is no CO, then ..no VC or HBS as it is still considered by FHA to be under construction until the CO is issued
Take Ron's advice and read the stuff he mentioned in his post on the HUD website.
The Cost Approach is to be completed on the specific form of a nationally recognized cost service. Most use Marshall and Swift and their form number is 1007. Make sure to reference the pages that you obtained the cost figures from...you no longer have to submit copies of the actual pages as in the old days as it is supposedly a copyright infringement.
Also, make sure you have a complete set of plans and specs, DOM's and the Builders Certification form. You must review the Builder's Cert form for accuracy. If it is not accurate, then state so in the URAR for the DEU to review the inaccuracies. Hey, builders have been known to overlook railroad tracks, main roads next to their homes....
Ben