Building regulations for wall return on porch

[Greeny12m]

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

 

[tony1851]

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.

 

[Notch7]

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

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

 

[Notch7]

Something to do with making sure the wall doesn't get blown over

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.

 

[tony1851]

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

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.

 

[Greeny12m]

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).

Mind you, seems a bit overkill for a porch.

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.

 

[tony1851]

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.