Fire protection for RSJ above ceiling.

Discussion in 'Builders' Talk' started by HandyAndy, Apr 11, 2004.

  1. HandyAndy

    HandyAndy New Member

    I am building a loft room in my bungalow with full building regs. approval. I have installed a 200mm x 100mm RSJ, above the ceiling, into which the 196mm x 48mm floor/ceiling joists are notched.

    The plans indicate that I should use 12.5mm fireline board for the ceiling below the RSJ, but they do not state that I should replace the whole of the existing ceiling with fireline. Should I?

    What I would prefer to do is remove 600mm of the existing ceiling (9.5mm plasterboard with 2mm to 3mm of plaster & artex) each side of the RSJ and replace it with 12.5mm fireline board and then to leave the rest of the existing ceiling in place and overboard the whole ceiling with another 9.5mm plasterboard and plaster skim. Will this all provide the necessary 30 minutes fire protection to the RSJ and ceiling/floor joists?

    Thanks.
  2. Plumbcrazy

    Plumbcrazy New Member

    I thought that just ordinary 1/2" plasterboard satisfied the building regs for fire protection of the RSJ? Check with Buildings Control.
  3. daz

    daz New Member

    one layer of fireline board itself should give you 30 mins fire rating. it is 15 mm, not 12.5 (regular plasterboard is 12.5).

    what you've described should give you 1/2 hr f.r. but you need to run it past the BCO as they tend to think there is room for interpretation.
    if you want exact fire ratings for different build ups check out the british gypsum website - navigate towards the white book. Daz
  4. jmcbuilders

    jmcbuilders New Member

    They like 2 layers
  5. oggie

    oggie New Member

    As JMC said
    Ive just finnished a hotel and all exposed sides of the rsj were covered in 2skins fireline
  6. daz

    daz New Member

    it's quite true - "they like two layers" - it nevertheless gives you 1 hr F.R.

    just as well as it makes it easier for the BCO. also if it's structure you're protecting it probably needs 1 hr anyway. Daz
  7. HandyAndy

    HandyAndy New Member

    Thanks to all of you for your suggestions. In the end I decided to speak to the BCO. He said that overboarding the existing 9.5mm plastered ceiling with another 9.5 board would give the necessary 30mins fire resistance.

    He also said that I could have painted the RSJ with fire proof paint before I installed it. If only I'd known that sooner!
  8. oggie

    oggie New Member

    Thats a new one although paint is fire risistant i didnt know hit was heat risistant and therefor wouldnt reflect the same heat as an 1" of gyproc would
  9. building control

    building control New Member

    Intumescent paint is
  10. daz

    daz New Member

    intumescent paint will fire protect your structure - but you musnt' forget part E as well.
    two layers of fireline board will help you here as well as they provide the necessary density.
  11. FLORBAORD

    FLORBAORD New Member

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