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Plasterboard / fire regs

  • 26-06-2016 09:51PM
    #1
    Keating31
    Registered Users, Registered Users 2 Posts: 9 ✭


    I am planning on fixing 50mm insulated plaster board to vaulted ceiling followed by timber clad underneath. Is the plaster board required for fire regs or can is instead fix an insulated ridged board follows by timber clad and meet fire regs?


Comments

  • #2
    Calahonda52
    Registered Users, Registered Users 2 Posts: 13,176 ✭✭✭✭Calahonda52


    The plaster board will meet the regs whereas the timber cladding may or may not, depends on the thickness, density, fixings etc so I would go with the pb, which, when properly taped and sealed, will also help with airtightness and vapour control.
    What other insulation is in the roof construction?

    “I can’t pay my staff or mortgage with instagram likes”.



  • #3
    Keating31
    Registered Users, Registered Users 2 Posts: 9 ✭Keating31


    Cheers. The makeup of the roof is as follows.
    Natural slate
    Counter battens
    Solitex plus roof felt - water vapour resistance <0.15mns/g
    175mm rafter with 180mm isover metac insulation - 0.034w/mk
    Isover Vario km vapour control membrane.

    Below this I am tinking 60mm PIR board to bring uvalue down to 0.14 for the roof, cladded with 12mm softwood timber nailed to battens underneath.


  • #4
    Calahonda52
    Registered Users, Registered Users 2 Posts: 13,176 ✭✭✭✭Calahonda52


    Is this built or in planning?
    Is the PIR with or without Alu foil?
    12mm softwood defo wont do for the fire regs

    “I can’t pay my staff or mortgage with instagram likes”.



  • #5
    Keating31
    Registered Users, Registered Users 2 Posts: 9 ✭Keating31


    Roof structure in construction. Filed back PIR with fire retardent paint on timber may be another option. Is there a minimun deth for timber.


  • #6
    Calahonda52
    Registered Users, Registered Users 2 Posts: 13,176 ✭✭✭✭Calahonda52


    PB is a clearly established solution for what you are doing, anything else will need certification/sign off which is beyond my pay grade.

    In passing, two observations off topic.
    Why mix membranes from two different suppliers?
    The membranes from each supplier are designed to work best with the others from the same stable, its not a takeaway menu where u can substitute flied lice for brown rice etc.

    Is your engineer happy to sign off on the mix?

    In addition, if the inside PIR is alu-foiled and taped, what is the isobar VCM designed to do as the foil in impermeable both ways.

    “I can’t pay my staff or mortgage with instagram likes”.



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  • #7
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    Stick with metac or similar (actual mineral wool would be best in the service cavity), avoid pir in this situation. Can you explain what rooms & why the timber finish is proposed?


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