we are in the process of building our systems built (modular) home. We want a full basement and our site would allow full walkout on one side. We would like to use a poured concrete basement wall, or perhaps a product like Superior Walls brand Xi plus. Our builder says that this type of foundation wall would not work with modular homes, and he wants us to use his concrete block "man". I have reviewed Modular Council's Builder's guide to modular home set up & completion, & cannot find any mention of pre-cast foundations, or see any reason why they cannot be used. Can you enlighten me?