Buying substantially refurbished house without cert of compliance

rajatparihar

Hi All, I have gone sale agreed to a house in Dublin which was originally constructed in 1980 but bought by an investor last year and substantially refurbished and extended. The work that he performed on the house are as follows:
1) Complete new insulation, state of the art air to water heating, underfloor heating, etc. everything seems fresh and new on the original build.
2) Extended to the rear which does not exceed 40 sq mtr.
3) Attic extension to be used as storage only.
4) Original house was E rated and now the fresh BER cert issued with B2

I have done a structural survey and nothing major comes in the report - though the structural survey was also a visual inspection along with dampness, pyrite test, etc.

So for the above refurbishments and extensions, the builder hired private contractors and did work on his own without the supervision of any qualified architect. Now at the time of sale, our solicitor asked for the Cert of Compliance with Building Regulations which he initially was not providing but after putting a wee pressure and a warning that we may not proceed without it - he got it arranged from a qualified charted engineer. Even this cert issued clearly states that the architect/engineer did not supervise the works and his inspection is visual only.

Such a substantial refurbishment has happened without any architect opinion is what I am doubting now (may be vendor wants to save few quids here). Vendor is ready to provide 20 years of structural guarantee on the rear extension which he sent an email to the selling agent confirming the same.

I liked this house a lot and don't want to withdraw my offer. What would you all suggest - shall I ask for any further info or legal detailed documents/ compliance certs from the vendor? What would be potential challenges in future if I buy the house without detailed cert of compliance? TIA