Section 288(1) of the Principal Act is amended as follows:

(a) by omitting from paragraph (b) "provision." and substituting "provision; or" ;

(b) by inserting the following paragraph after paragraph (b) :

(c) if the provision of the Building Regulations applies a standard or requirement by reference to a document that is subsequently amended, if the building surveyor for the work certifies that substantial progress had been made in the design of the work before the document so applied was amended.