Smallest spiral staircase

[Simplez]

I am considering a loft conversion and thinking of ways to get stairs in - what is the smallest diameter spiral staircase that is legal?

I have a space that is 1m x 0.8m to rise 3m.

 

[johnny2007]

Better check with building control.
Here in west London they don't like spiral staircases, although not illegal.

 

[foxhole]

Think you need an architect?

 

[freddiemercurystwin]

Think it's 600 wide for the stair width so you've no chance in a void 1mx0.8m. You could consider a spacesaver or similar.

 

[Tigercubrider]

If it's only a case of emergency exit I guess you could consider a fireman's pole?
Could add a bit of spice if it entered through one of the other bedrooms.

 

[tony1851]

If you are going up 3m, you would need 14 risers, = 13 treads; there is no way you would get any compliant staircase within 1m x 0.8m. Even an alternating tread stair would need to be very steep (and dangerous).

 

[Simplez]

I called BC and an SE - both were happy to give advice over the phone.

You are all correct - its a no go - the only way is to take the stairs from the smallest bedroom into the attic - so it would be sacrificing one small bedroom to make a larger attic bedroom. Overall not really much benefit.

 

[freddiemercurystwin]

If you are going up 3m, you would need 14 risers, = 13 treads; there is no way you would get any compliant staircase within 1m x 0.8m. Even an alternating tread stair would need to be very steep (and dangerous).

Hey tony, in Part K (extract below) you can get away with a fixed ladder if just the one habitable room, a ships ladder I suppose, do you know what the relevant BS or similar for that might be?

1.32You may use a fixed ladder – with fixed handrails on both sides – only for access in a loft conversion that contains one habitable room, and only when there is not enough space without alteration to the existing space for a stair that satisfies the guidance for dwellings in paragraphs 1.2–1.24.

 

[tony1851]

Hey tony, in Part K (extract below) you can get away with a fixed ladder if just the one habitable room, a ships ladder I suppose, do you know what the relevant BS or similar for that might be?

1.32You may use a fixed ladder – with fixed handrails on both sides – only for access in a loft conversion that contains one habitable room, and only when there is not enough space without alteration to the existing space for a stair that satisfies the guidance for dwellings in paragraphs 1.2–1.24.

BS 5395 Part 4 (stairs for limited access) is worth a read. For a single-room loft conversion (or a single room basement conversion), you can have traditional stairs with treads as shallow as 180mm, as long as the pitch is no more than 50.7°, at least 600 wide and with handrails both sides.
Far safer than the alternating tread stairs.
I can't see why the OP is so constrained by such a small opening into the loft; and to loose one bedroom to gain another is potty. I suspect he may be working to the usual 42 degree pitch without realizing that there are alternatives?

 

[freddiemercurystwin]

Ok ....... sure but that's still a stair, what about the 'fixed ladder' as stated in Part K? Any idea?