+ 1 what mathepac has posted, garclo, also; -
There are more important issues to deal with than just the lack of an RSJ.
After all, if its been constructed for several years as it is, there seems to be no imminent danger of collapse.
The conversion must be done correctly in terms of the upgraded floor joists.
[this is not a simple matter so halving the span by inserting an RSJ]
The access must be a permanent stair if its to a habitable room - it cannot be a ladder or Staighre unless its only storage.
The fire protection of he stairs, the alarm system and/or alternate escape routes via velux or dormer windows must all be fully addressed.
Read these guidance notes for a brief overview.
Loft Conversion Leaflet
http://www.environ.ie/en/DevelopmentandHousing/BuildingStandards/PublicationsDocuments/FileDownLoad,1657,en.pdf (http://www.environ.ie/en/Development...ad,1657,en.pdf)
Loft Conversion Leaflet Amendments
http://www.google.ie/url?sa=t&source...z6tsPPzBE3N7OA
The information has also been posted to this forum on at leas three occasions - four now.
ONQ.
[broken link removed]
All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.