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Building regulations for wall return on porch

Discussion in 'Building Regulations and Planning Permission' started by Greeny12m, 5 Mar 2021.

  1. Greeny12m

    Greeny12m

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    Hi,
    I'm currently mid-build on a 1.6m deep x 2.8m wide porch. I've been told by the builders that I can't put the door where I want to (very close to one edge) because building regs require a >600mm return. Something to do with making sure the wall doesn't get blown over. We live near London so low wind risk.

    I've been lead to believe that if a structural engineer can provide calculations to support a smaller return that it should be accepted by the building inspector. Can anybody tell me if that is true and what the likely result would be (we're hoping for ~400mm return external with a 300mm cavity wall)?

    Cheers
     
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  3. tony1851

    tony1851

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    You do not need Building Regulations approval for a porch, so you can have the return any size you like.

    It is true that calculations can usually show that a smaller return is acceptable when considering wind load.

    However, bear in mind that doors are heavy, and a slamming door can put considerable force on a narrow return; I'd be dubious about any return supporting a door being less than 2-bricks (450-ish) wide.
     
  4. Notch7

    Notch7

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    I suppose it could be a porch open to the house....if that's still called a porch?
     
  5. Notch7

    Notch7

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    3 bricks = 675mm is often a rule of thumb as the min for a wall to act as a buttress against wind load.

    You can have it as small as you like if you put in a steel post - usually cast into the founds or bolted to them.
    Mind you, seems a bit overkill for a porch.

    Is there a bigger return the other side - if there is, a steel across the top strapped in place would link them together.
     
  6. tony1851

    tony1851

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    I think once you take the front door off (or replace it with an internal-grade door) it becomes an extension to the house and building regs then apply.
     
  7. Greeny12m

    Greeny12m

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    Yes, new front door so building regs apply (doing it now saves the hassle getting retrospective signoff to sell in the future), it is also >3m² so is past permitted development and required planning (part of a larger project from previous owners).

    I get there is a reason for the rules but it does seem overkill I agree, especially for such a small area wall and single story. Seems like this is not scenario that the rule is designed for, there should be a loophole!

    The door has sidelight so will be total 1300mm wide leaving a decent return on the far side. Sadly it sounds like this inspector is a bit of a stickler so I am just going to have to go with the rules *sigh* (don't want to pause the build to get calculations done for a windpost). Perhaps we will try and get some extra space back inside by using thinner blocks for the inner skin.

    Cheers for the input folks.
     
  8. tony1851

    tony1851

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    If there is 'a decent' return on the other side; and if the door is hinged at the decent return; and if you can connect the two brickwork returns with a suitable beam, the inspector might let you get away with a smaller return.
    This is because the wind load is then 'shared' by the two brickwork returns.
     
  9. DIYnot Local

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