The approved documents are ‘standard’ ways of getting Building RegulationsThese are the legal regulations which govern how a house is constructed. (not to be confused with Planning Permission which is about whether you are allowed to build the house at all or what it might look like) see Building Regulations) approval. If you follow the principles and rules given in the documents you can be sure that they will be approved.
The documents are available HERE
Of course you don’t have to use the Approved Documents, as the Regulations make clear:
In fact the Approved DocumentsThese are a part of the Building Regulations which ensure, if you follow them, that your plans will be automatically approved. The full set of the documents is available here are a bit of a mishmash of ‘rules of thumb’ and technical standards and they have gaping holes in them. Whereas, for instance, there are many pages on how to construct traditional masonry walls, there is nothing about timber frame construction except the odd reference to British standards.
They are also struggling to keep up with the times. If zero energy new house building is introduced in 2016 (as is planned) then whole swathes of the Approved Documents will need rewriting.
There are other ways of satisfying the regulations. For instance the regulations make copious references to BSBritish Standard, BS EN and BS EN ISO standards which may be another way of fulfilling the criteria. It is even possible in some very rare cases to prove that something works by building it first and then testing it afterwards (though this is not for the faint hearted).