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Cavity width - is 100mm sufficient?

  • 27-03-2016 03:13PM
    #1
    dubber
    Registered Users, Registered Users 2 Posts: 363 ✭✭


    Building an extension to our house and looking at a cavity wall with a 100mm cavity with blown bonded bead insulation. Aside from, u-value, are there any issues with going with a cavity this size, space is at a premium, so reluctant to go much bigger.


Comments

  • #2
    MicktheMan
    Registered Users, Registered Users 2 Posts: 2,952 ✭✭✭MicktheMan


    Imo, no issues with 100mm filled cavity is space is at a premium (if it was me I would go for as wide a cavity as I could get away with).
    As space is at a premium, a better idea might be to use aerated concrete blocks for the inner leaf.
    And .... don't forget your air tightness.


  • #3
    Curly Judge
    Registered Users, Registered Users 2 Posts: 2,708 ✭✭✭Curly Judge


    MicktheMan wrote: »
    Imo, no issues with 100mm filled cavity is space is at a premium (if it was me I would go for as wide a cavity as I could get away with).
    As space is at a premium, a better idea might be to use aerated concrete blocks for the inner leaf.
    And .... don't forget your air tightness.

    How do those aerated blocks work out in a load bearing situation?


  • #4
    MicktheMan
    Registered Users, Registered Users 2 Posts: 2,952 ✭✭✭MicktheMan


    Curly Judge wrote: »
    How do those aerated blocks work out in a load bearing situation?
    Not an issue with proper design and reinforcement. Obviously a structural engineer is required.


  • #5
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,147 Mod ✭✭✭✭BryanF


    Curly Judge wrote: »
    How do those aerated blocks work out in a load bearing situation?

    They come in 3/5/7kn


  • #6
    dubber
    Registered Users, Registered Users 2 Posts: 363 ✭✭dubber


    Another question, I've had a few opinions on this, but want to see what boardsies think. The back of the house is L shaped (i.e. has a gable end) built with solid wall. The extension will match the width of the gable and then narrow (an L itself). At some point I plan to EWI the main house, would the best approach for the extension be to use solid wall where it meets the main house (with EWI in future) and then start the cavity wall at the right angle where the extension narrows?


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