My understanding is that the Code is binding on the house builders as part of the CPRs, from Consumer Protection Regulations:
PART 2
PROHIBITIONS
Misleading actions
5.(1) A commercial practice is a misleading action if it satisfies the conditions in either paragraph (2) or paragraph (3).
...(3) A commercial practice satisfies the conditions of this paragraph if:
(a) it concerns any marketing of a product (including comparative advertising) which creates confusion with any products, trade marks, trade names or other distinguishing marks of a competitor; or
(b) it concerns any failure by a trader to comply with a commitment contained in a code of conduct which the trader has undertaken to comply with, if
(i) the trader indicates in a commercial practice that he is bound by that code of conduct, and
(ii) the commitment is firm and capable of being verified and is not aspirational,
My understanding is that the Consumer Code for Homebuilders, is a plain English version of what a house builder is required to do by law. It sets out their responsibilities clearly. But at the same time any requirements stipulated in the code are then binding on the house builder (assuming that they don't mean the consumer has less rights - it can only provide extra protection).
Also from the code:
Part 2 sets out the prohibition on unfair commercial practices. The prohibition relates to commercial practices that contravene the requirements of professional diligence, misleading actions, misleading omissions, aggressive commercial practices and commercial practices of the type specified in Schedule 1. Part 2 also imposes a prohibition on the promotion of unfair commercial practices by persons responsible for codes of conduct for traders. The prohibitions will be enforceable through the procedure for the enforcement of Community infringements in Part 8 of the Enterprise Act 2002.
The problem goes back to the enforcement - the Homebuiders Code is not enforced.