Cavity steel beam sizes

[yahoo5000]

Hello i am looking for information on what size is steal beams i should put into cavity wall there is 3 meter opening on a corner , i was thinking to put 2 beams 100mmx200mm of a 3 meters . But not 100% sure if that is sufficient . I have plans attached . There is currently extension build already with doors but want to open all the way it is the door way from dining room to family room on the plans ( kitchen , dining room , utility room is 1 store extension . everything else is two store house . 

 

P.S floor joist do not sit on the walls that being removed there is another beam already installed dividing family room into half and floor joist sits on it 

 

Another question i have is do beams have to be on the same level or can one be higher other is lower ( i dont see reason why not but prefer to double check on other opinions ) .

 

And last question is how do you sort out DPM in this instance as well as cavity gap between beams .

 

This is more informative sample ( the walls that being removed is archway ) 

Edited November 9, 2023 by yahoo5000

[bassanclan]

You need a structural engineer

[yahoo5000]

what about DPM , i mean at the end cavity gets filled with beads , but i feel like if there is no dpm above steel beam moisture would just soak into plasterboard underneath also if there is dpm then it would lead to extension part of the house witch would be attic based on ceiling heigh witch is also probably not okay ? the way i imagine this is need to divert to the sides of the beam so moistre could run down all the way to the lower installed DPM 

[MartinGT]

Get a proper SE to have a look on site.