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Insulation in ceiling following roof pitch?

  • 19-11-2010 3:02pm
    #1
    no nails niall
    Closed Accounts Posts: 97 ✭✭


    Hello,

    The ceiling on the main living space on my build will follow the roof pitch upto rigde level giving a nice high space in this south facing room.

    The roof rafters will probably be 200x36mm supported on purlins.

    Leaving the 50mm air gap would only mean that i can pack in 150mm insulation. This seems a little light, especially since the walls will be 215 therman block, 100 cavity (with 75 insulation) and 100 rendered outer leaf.

    Any advice on this? Would 150mm be enough or are there any construction methods to increase insulation?

    Help greatly appreciated!

    Niall


Comments

  • #2
    soldsold
    Registered Users, Registered Users 2 Posts: 552 ✭✭✭soldsold


    You could counter batten in the opposite direction to the rafters with 2 No. 50mm roofing battens, then fill this 100mm depth with insulation. Insulated plasterboard is another option. Either will also reduce cold bridging and could be combined if you can afford the increased depth or need the extra insulation. I'm using these battens in some of my sloping roof


  • #3
    paddy147
    Banned (with Prison Access) Posts: 15,858 ✭✭✭✭paddy147


    Xtratherm insulation board and then 38mm insulated plasterboard for the ceilings.Thats what I did in my house.

    Snug as a bug in a rug now.


  • #4
    bakerbhoy
    Registered Users, Registered Users 2 Posts: 639 ✭✭✭bakerbhoy


    xtratherm rafter loc between rafters and insulated plasterboard below as paddy 147 has said.
    I used 175mm between and 50mm below

    (The roof rafters will probably be 200x36mm supported on purlins. )
    If your timbers are not yet in you can still use deeper rafters


  • #5
    no nails niall
    Closed Accounts Posts: 97 ✭✭no nails niall


    bakerbhoy wrote: »
    (The roof rafters will probably be 200x36mm supported on purlins. )
    If your timbers are not yet in you can still use deeper rafters

    Is it possible to get 275x36mm rafters? This would mean I dont have to make up the depth below with battens.

    Or

    Can insulated plasterboard be bought at 90mm?



    Whats the best cost wise?

    Cheers, Niall


  • #6
    Southern Comfort
    Registered Users, Registered Users 2 Posts: 186 ✭✭Southern Comfort


    no nails niall wrote: »
    Is it possible to get 275x36mm rafters? This would mean I dont have to make up the depth below with battens.

    Or

    Can insulated plasterboard be bought at 90mm?



    Whats the best cost wise?

    Cheers, Niall

    Hi Niall.
    150mm of Rafterloc http://capitalgreenenergy.com/brochures/Xtratherm_Rafterloc.pdf with a 50mm air gap above, with 50mm of insulation on plasterboard underneath, would give you a U Value of 0.14.

    According to this, Xtratherm can supply plasterboard 102.5mm thick which has 90mm insulation. http://www.xtratherm.com/products/thinrthermalliner.php

    Kingspan probably supply the same thickness in K18 insulated plasterboard but I can't get onto their website to get a link for you.


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  • #7
    no nails niall
    Closed Accounts Posts: 97 ✭✭no nails niall


    Southern Comfort wrote: »
    Hi Niall.
    150mm of Rafterloc http://capitalgreenenergy.com/brochures/Xtratherm_Rafterloc.pdf with a 50mm air gap above, with 50mm of insulation on plasterboard underneath, would give you a U Value of 0.14.

    According to this, Xtratherm can supply plasterboard 102.5mm thick which has 90mm insulation. http://www.xtratherm.com/products/thinrthermalliner.php

    Kingspan probably supply the same thickness in K18 insulated plasterboard but I can't get onto their website to get a link for you.

    Good help everyone.

    Going to go with the 150 rafter lock with 50 ventilation above and a 92.5mm thick insulated platerboard below.

    Cheers, Niall


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