Unfortunately a siret number does not reflect any qualification in any feild of trade, any one could gain a siret numbr for a labourer etc and trade as a General builder, all a siret number proves i sthat they are paying a self employed social corribution.

Regardl;ess of how nice their signs are etc make sure they can prove they have qualiification either from an english college or a reputable employer ei Bovis French kier etc. as when we had work done my father a qualified MCOB qualitiy survayer asked of see qualification to they could be contacted and none of the builders returned!!!!

contact the place of their empler in england or college to clear up any doubt as building work is expensive and you dont wanna be had regardless of avdertising and how many tool sthey have if they have nothing to hide they will be more than happy to prove their qualifications.
Unfortunatey i know a builder (supposedly ) in 87 how was a french polisher and when in france suddley become a builder. be aware