This sounds like a more general initial conversation between the owner and the committee who would need to make themself informed beforehand. The scope of works mentioned by a roof change initially sound quite major and beyond the authorization of the committee, and requiring an agm/egm vote with suitable and somewhat indepth information for all owner’s to make a decision on. If the owner or the builder really know what’s involved here would they not understand what they need provide to make a convincing, legally do-able case? If I owned there then there’s no way I’d even consider changes to that degree which will likely greatly affect the look of the whole property and the precedent it would establish without full information to sway my opinion and vote choice.