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Distance of openings from wall

Discussion in 'Building Regulations and Planning Permission' started by liftfan, 8 Jun 2019.

  1. liftfan

    liftfan

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    D90F9873-735B-4FD1-B315-78A39322FB23.jpeg



    I’m planning to construct the small front extension (the white rendered part) out of thin joint aircrete blocks. In the picture I’ve arrowed the wall which breaks this rule:


    OPENINGS AND RETURNS
    An opening or recess greater than 0.1m2 shall be at least 550mm from the supported wall (measured internally).


    The external measurement is only 450mm i.e. one block. Is there a way round this?

    Thanks.
     
  2. tony1851

    tony1851

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    As it's only a small window opening, it doesn't matter if the return is only 450 on the outside; if it was a door opening, it would be a different matter.

    The 550 measurement you quote is from Approved Doc A, which gives "deemed to satisfy" provisions for masonry walls. All this means is that if you keep to the measurements shown, the Building Inspector can't pull you up. But if you go outside those limits, it doesn't mean that what you have done is non-compliant; all it would need would be either to prove with figures that the reduced return would be sound, or be fortunate enough to have a building inspector who had common sense (there are a few around).

    Do it in 7N block and it will be fine.

    BTW, why do it in thin-joint work? It is generally only used for large-scale developments and will be expensive for a small extension. Most brickies are not familiar with the method.
     
  3. liftfan

    liftfan

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    Thanks for the reply Tony.

    Why thin joint? It’s only a small extension, I’m doing most of it myself and I just fancy giving it a go! From what I’ve read it’s more common outside of the UK.

    I’ve read this :

    https://www.hhcelcon.co.uk/sites/de...ts/Designing-and-Building-with-Aircrete_0.pdf

    and was planning on 7N aircrete all over due to the diagram on Page 4.


    Should I just remove that line about the 550mm from my Building Regs application when I submit it and wait and see?

    Many thanks.
     
  4. Leofric

    Leofric

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    Wall ties don't fit into joints in thin joint blockwork and if I recall correctly it doesn't course in with brickwork. When it was used on a job I worked on the bricklayers were not familiar with the system and didn't like using it. Better to use ordinary blocks and 10mm mortar joints in my opinion.
    ps although I did get a free YTONG baseball cap out of it .
     
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  5. ^woody^

    ^woody^

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    Thin joint is crap for anything other than long straight walls with the occasional opening that conforms to the bond. Its particularly crap for small extension, renovation and alteration work.

    There is very little room for adjustment and relies on the first course, the first block being dead perfect in level and plumb, because after that all deviation errors are cumulative and difficult to pull back.

    You must build the blockwork first, so its crap yet again for setting out the openings, and crap for having to knock the ties in afterwards, and doubly crap if you don’t let the wall set long enough and knock it too soon.

    And crap to use in warm weather.

    There’s a bit of a theme.
     
  6. liftfan

    liftfan

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    It’s a good point about the wall ties. Both leaves will be blockwork so would need thin ties which don’t seem very common.

    Have found some here
    http://www.tackburn.co.uk/wall-ties.html

    but it’s probably not a good sign if the builders merchants don’t stock them!

    Just read your post Woody and I’ve gone right off the idea! Oh well.
     
  7. tony1851

    tony1851

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    Your post is full of crap.
     
  8. Notch7

    Notch7

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    Ive seen the sales blurb for thin jojnt, but never see it used.

    But then builders like traditional methods, most builders dont like foundation blocks.
     
  9. tony1851

    tony1851

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    It's a Continental thing hence, as per Woods, it's crap.
     
  10. Leofric

    Leofric

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    correct decision in my opinion (y)
     
  11. Leofric

    Leofric

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    Why don't builders like foundation blocks :?:
     
  12. ^woody^

    ^woody^

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    I do try and be consitent. :cautious:
     
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  13. Notch7

    Notch7

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    Mostly I think because most extensions are concrete trench fill, the finished level of top of found may not correspond to blocks -often a mixture of blocks, engineering and facework is used to reach dpc level. For most extensiins its hardly worth putting in 1 row of trench blocks.
     
  14. Leofric

    Leofric

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    Thought concrete strip foundations were the preferred option unless there is a reason for doing otherwise, certainly on new build housing.
     
  15. Notch7

    Notch7

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    I dont think Ive come across any builder doing strip footings for extensions of any size
     
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