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what's a typical wall these days?

  • 09-05-2012 1:56pm
    #1
    JohnBoy
    Registered Users, Registered Users 2 Posts: 2,342 ✭✭✭


    So a few years ago I was following this forum quite a lot as we were hoping to build a house, then it dropped off the prospects list, and now it's kinda back on.

    we need to cost it at least so we know how much negative equity hit we can take on our current house :(



    We're meeting with our architechtural technician next week, but in the meantime I'm trying to study up on what's currently happening out there.

    we're building a traditional two storey (in the cork design guide sense of traditional) house, and I'd like to go with a fairly traditional wall in that I'd like concrete inside and out. I dont like insulated slabs nor am I mad keen about external insulation.

    What's the "normal" cavity wall makeup these days?

    I've done some searching but not finding much of what i want.


Comments

  • #2
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    JohnBoy wrote: »
    What's the "normal" cavity wall makeup these days?
    150-300 cavity (generally a min of 200mm if you wish fully fill with bonded bead (0.033 w/mk) and avoiding dry-lining) I'm more inclined to go with the 250mm min depending on the external surface wall area and what the phpp results are like. there are those that go for the traditional rigid boards in the cavity but the issue there is relying on the guys on site to fit them exactly with not gaps.


  • #3
    sydthebeat
    Subscribers Posts: 42,171 ✭✭✭✭sydthebeat


    Our standard specification at the moment "just to meet the regs" is a 150mm cavity pumped.

    there is a kind for breaking point in a cavity wall in which cavitys over 150mm need specialist structural engineering input into design and certiifcation as, in my understanding, the BS for standard cavity ties and blocks only covers up to 150mm.

    this cavity would be pumped as i view a pumped insulation system as performing better in the long run than board insulation.


  • #4
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,146 Mod ✭✭✭✭BryanF


    what Uvalue are your BER'ing in with a 150mm pumped?


  • #5
    sydthebeat
    Subscribers Posts: 42,171 ✭✭✭✭sydthebeat


    U-value [W/m2 K] 0.20
    Layers
    Thickness Conduct'y Resistance
    [mm] [W/m K] [m2 K/W]
    Internal surface resistance
    0.130.
    Plaster
    13
    0.180----0.069.
    Concrete block Dense
    100
    1.150----0.087.
    Full Fill Bead
    150
    0.033----4.545.
    Concrete block Dense(2)
    100
    1.150
    0.087.
    External rendering (cement/sand)
    19
    0.570----0.033.
    External surface resistance
    0.040.
    .
    Upper/lower resistance 4.992 / 4.992 W/m2 K

    Correction for air gaps / mechanical fasteners 0.000 W/m2 K


    by uvaluate


  • #6
    sinnerboy
    Closed Accounts Posts: 5,433 ✭✭✭sinnerboy


    Another "standard" wall is the the 100 cavity with partial fill and dry line internally. Read ( lots of ) other threads as to why this is not advised. I only mention it as it will be mentioned to you "in real life" by some "builders" ( and to be fair by some out of date professionals too )


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  • #7
    ShiverinEskimo
    Hosted Moderators Posts: 18,115 ✭✭✭✭ShiverinEskimo


    sinnerboy wrote: »
    Another "standard" wall is the the 100 cavity with partial fill and dry line internally. Read ( lots of ) other threads as to why this is not advised. I only mention it as it will be mentioned to you "in real life" by some "builders" ( and to be fair by some out of date professionals too )

    Can you link to some of these threads or post a brief summary why this is not advisable?


  • #8
    sinnerboy
    Closed Accounts Posts: 5,433 ✭✭✭sinnerboy


    1. Drylining cannot be continuous at junctions with floors/roof/internal walls so the calculated U Value is degraded by high thermal bridges.
    2. You loose thermal mass from the blockwork inner leaf
    3. Ever tried to hang a curtain pole in a drylined building ?


  • #9
    amen
    Registered Users, Registered Users 2 Posts: 2,781 ✭✭✭amen


    out of interest why not look at a prefabricated wall/house ?


  • #10
    JohnBoy
    Registered Users, Registered Users 2 Posts: 2,342 ✭✭✭JohnBoy


    sinnerboy wrote: »
    Another "standard" wall is the the 100 cavity with partial fill and dry line internally. Read ( lots of ) other threads as to why this is not advised. I only mention it as it will be mentioned to you "in real life" by some "builders" ( and to be fair by some out of date professionals too )

    Cheers for the info, 150 pumped is minimum nowadays, I see. I'm guessing we'll need an engineer anyway as I'm hoping for a concrete first floor so a bit wider is probably achievable. 300 sounds huge


    I'd agree with all your sentiments, and more. The insulated slab is a great product for rennovations and insulated ceilings that go up into the roof, but I think they're used as an excuse to not chase walls or do a lot of other things properly and hide shoddy blockwork.

    amen wrote: »
    out of interest why not look at a prefabricated wall/house ?

    To be honest, conservatism. This is the house I intend on being carried out of, I'm not looking for anything adventurous, it's hard to argue with concrete in this situation.


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