TGD-K query - Attic/Loft Stairs Width

spockety

I know that Attic conversions and attic stairs queries have come up here before, but I'm not sure I've seen a definitive answer when it comes to the minimum width required to satisfy building regs.

TGD-K says minimum width for a private stairs is 800mm. However, there's then a section dealing with allowances/exceptions for Loft Conversions (1.1.15) where there's not enough space to accommodate pretty much every measure listed before it in the doc. However, the only two designs called out in this paragraph are either spiral stairs or alternating tread stairs as possible ways around space limitations for attic stairs.

Is the reading of this that they are literally the only two acceptable forms of design where there are space limitations, or that they are just two examples that are called out, and there is some more lateral scope to come up with compromised designs specifically for attic stairs?

Context is a proposed design for a stairs that 600mm wide and with a pitch of about 44 degrees instead of the otherwise specified max in the TGD of 42.

Loft Conversions

1.1.15 Spiral stairs with goings less than recommended in Table 2 of BS 5395 Part 2:1984 and alternating tread stairs would not normally be regarded as acceptable. However, they may be considered in the conversion of a loft where space is limited i.e. where there is not enough space to accommodate stairs satisfying par. 1.1.1 to 1.1.14 above and the stairs serves only accommodation which will be used infrequently and, where the accommodation includes only one habitable room. Alternating tread stairs should be in straightflights, have handrails on both sides and the treads should have slip resistant surfaces. The goings and rises for the wider parts ofthe steps should comply with par. 1.1.4.

Mellor

Spiral stairs cover a lack of area. Alternate thread stairs, deal with a lack of distance.

I can’t think of a situation where 600 in width fits but not 800. That said, industrial stairs/ladders are often 500-600

spockety

https://www.boards.ie/discussion/comment/123607037#Comment_123607037

Thanks Mellor. Situation would be that an 800mm wide stairs would encroach too much on the first floor landing area (from a safety/practical perspective as opposed to anything aesthetic) vs. a 600mm wide stairs.

How do industrial stairs get around the 800mm specification do you know?

Penn

Industrial stairs aren't going to be used by children, persons with physical difficulties, and won't be used as a means of escape where persons may be trying to escape during a fire when there is heavy smoke and no lighting (industrial areas would have emergency lighting, people wouldn't be asleep when the fire alarm is activated so are more likely to be alerted to a fire earlier than people in a house sleeping).

spockety

https://www.boards.ie/discussion/comment/123607217#Comment_123607217

Yeah that makes sense.

In a domestic fire I think I'd rather be bailing down a 600mm wide standard stairs than an alternating tread stairs in the dark, mind you 😬

Gumbo

https://www.boards.ie/discussion/comment/123607294#Comment_123607294

Are you trying to get official bedroom status in the attic space?

Mellor

https://www.boards.ie/discussion/comment/123607185#Comment_123607185

Solution would probably be to replan the landing and stairs so it doesn’t encroach

spockety

https://www.boards.ie/discussion/comment/123608381#Comment_123608381

No that's not possible due to the headspace requirements.

However I would still be looking to adhere to as many regulations as possible that do go with that status, including/especially the fire related regs etc. The stairs width is a challenge though.

spockety

https://www.boards.ie/discussion/comment/123608400#Comment_123608400

Yeah, I was hoping to avoid that, but it may not be possible.

Gumbo

https://www.boards.ie/discussion/comment/123608402#Comment_123608402

most important one is means of warning, then means of escape. Make sure the attic room has linked smoke detection and a self closing fire door.

Alternative means of escape/rescue though a Velux to the rear then.

After that, a narrow stairs will be the pinch point alright but a single person who is familiar with the layout should be ok. Especially as the room is only storage, games room or office. but the big kicker than many forget, is the who point of the above is to protect the stair enclosure. If you don’t fit self closers to all the other rooms at first and ground floor then fire of smoke could trap the person in the attic.

spockety

https://www.boards.ie/discussion/comment/123608408#Comment_123608408

Yeah, will be accounting for all that 👍

I'm still not sure on the answer to my original question though , is a narrower straight stair case as acceptable as a spiral or alternating tread staircase when it comes to stairs leading to loft conversions? Clearly the regs allow for circumstances where the usual requirements can't be met, but I find it a bit odd that the only examples given are spiral stairs or alternating tread.

Gumbo

https://www.boards.ie/discussion/comment/123608568#Comment_123608568

Technically you’re not carrying out a lost conversion as it’s inhabitable space.

It’s an infrequent spaces used by the occupiers. It’s non habitable so the habitable requirements don’t apply to you.

Mellor

https://www.boards.ie/discussion/comment/123608708#Comment_123608708

That's true, but a compliant stairs is nothing to do with habitable requirements. It's a stair requirement. And there no exemption for a stairs to an attic that I am aware of (other than spiral, and alternate thread).

https://www.boards.ie/discussion/comment/123608568#Comment_123608568

If you take TGD word for word It needs to be 800mm wide.