Applications relating to proposed construction must be accompanied by an agreement in form satisfactory to the Secretary, executed by the seller or builder or such other person as the Secretary may require, and agreeing that in the event of any sale or conveyance of the dwelling, within a period of one year beginning with the date of initial occupancy, the seller, builder, or such other person will at the time of such sale or conveyance deliver to the purchaser or owner of such property a warranty in form satisfactory to the Secretary warranting that the dwelling is constructed in substantial conformity with the plans and specifications (including amendments thereof or changes and variations therein which have been approved in writing by the Secretary) on which the Secretary has based on the valuation of the dwelling. Such agreement must provide that upon the sale or conveyance of the dwelling and delivery of the warranty, the seller, builder or such other person will promptly furnish the Secretary with a conformed copy of the warranty establishing by the purchaser's receipt thereon that the original warranty has been delivered to the purchaser in accordance with this section.