Extractor through fire check

Hi All, hope you can give me some advice please. I've got a kitchen and dining room that's been knocked through into one, with a couple of
RSJ's supporting the first storey. Going for a kitchen refurb and planning to do a ceiling drop to hide the RSJ's and give a clean look. I believe that i need to either use a fire rated board or double line with 12.5mm plasterboard across the whole ceiling to provide fire integrity, however the kitchen plans include a chimney island extractor attached through the ceiling adjacent to an RSJ. I'm concerned that this breaches the fire check. Would fire retardent ducting maybe with a fire retardent collar above the ceiling be sufficient or is there a better solution?

Give your local Building control a ring they are helpful usually and it would probably vary from area to area what you'd get away with

Thanks for your response.

If you protect the beams, then you should not have to protect the whole ceiling

Thx Woody- that's going to be the most straightforward solution, and then do the ceiling drop below that level. I believe you've previously recommended chicken wire or similar wrapped round the RSJ's to give any battens and wedges additional security. As there are walls sat on the top edges of the RSJ's I can't wrap right round, so I'd only be able to secure/ tension it off the floor joists above which seems less than ideal as it would be exposed. What's your solution?

You will have the required 1/2 hour protection to the new ceiling, and I presume you will leave the existing plaster ceiling in place to give protection to the upper floors.

So you have a void which is a potential fire route.

Will the new ceiling be treated as cosmetic, or do you need to have protection within the ceiling void - you will need to clarify this.

Encasing the beam to give it 1/2 or 1 hours protection will do, but don't have any exposed floor timbers either. You only need to protect exposed sides of the beam, so fit your plasterboard or Masterboard or whatever around the beam and make good any gaps to the existing floor joists. You can fit noggins in the beam web, and if you have them a bit proud of the beam, then you can nail the soffit board up to these too

Will the flue need to be protected too - possibly wrap some rockwool around it

Incidently, can't the beam go up into the floor void, so as to then avoid the need to lower the ceiling?

Thx Woody

The RSJ's are already in place. The main RSJ supports the floor joists spanning the width of the house with a stud wall above which also carries load from the roof, whilst a smaller RSJ is bolted up to it running parallel with the joists supporting a solid wall above. The original lath and plaster ceiling is in place on the dining room side but not in the kitchen -basically it collapsed. Hence my original plan to use the new ceiling to provide the protection and protect the extraction conduit. I'd add that the original ceiling height is eight foot six, and the RSJ will reduce the new height to just under eight foot.