Part K handrails for stairs

[Dee J]

Anybody understand part K enough to say if there is a required thickness of handrail for a domestic building? Background...Trying to finish off our existing house prior to the hoped new-build. We've got a narrow staircase in a part of the building not yet signed off by bc. We've never had a handrail fitted. It's only eleven risers, with the first six treads forming a 180 degree turn. Looking to fit the minimum required handrail around the outer side of the curve. Also, as far as I can interpret, the first two steps need no rail. 

The only dimensioned diagram 1.13 seems to reference para 1.36 for non domestic.

Why am I questioning this? It would fit the look of the stairs better to have a skinny 25mm metal rail than the usually supplied thicker ones. Do you think this will cause problems?

Thanks

Dee

[Ian]

Part K is simply the Approved Document and is not the actual Building Regs which means that you may be able to negotiate something different from Part K if you can convince your Building Inspector.

 

If we are just looking at the wording in Part K then there's nothing to prevent you from using a handrail that is different to the thicknesses shown in diagram 1.13 as that diagram is for "buildings other than dwellings". I would however disagree with you when you say that that the first two steps need no handrail as I don't think paragraph 1.37 provisions should be read in that way.

 

I think paragraph 1.37 means that if you only have a flight of 2 risers or less then you don't need a handrail. Any flight with 3 risers or more then the whole flight needs handrails.

Edited March 6, 2018 by Ian

[Hecateh]

This site seems to explain the regulations well and doesn't mention a minimum diameter for hand rails.  It also says that the first 2 stairs do not need a handrail

 

https://www.wonkeedonkeerichardburbidge.co.uk/building-regulations-explained/

[StructuralEngineer]

As far as I know the thickness requirement for handrails comes more from their need to be strong enough to hold someone up when they lean on it or trip and grab hold of it. The accepted deflection limit is 25mm, and the codes say that for a domestic stair the rail should be capable of taking 0.36kN per metre, which is 36kg. You could take a 36kg weight and hang it at mid-span between two supports, and see how much movement you get. These regs only apply when the handrail is stopping you falling down a drop of 600mm or more ("protection from falling").

 

In practice, the real limiting factor is whether you can get your hand comfortably around to grip onto it, and for this reason the Part K document states a minimum of 50mm gap to the wall and minimum 32mm diameter rail -- see the excerpt below from Part K page 16, diagram 1.13. I'd never noticed before that this seems to relate only to non-dwellings, so you may be right that this doesn't apply either.

 

Edited March 9, 2018 by StructuralEngineer

[Ian]

@StructuralEngineer

The diameter requirement of 32mm - 50mm on that diagram from part K is like that because some people have trouble gripping a handrail which is narrower than that. 

 

Building Inspectors will usually accept the handrail recessed into a hollow in the wall if space is tight.

[StructuralEngineer]

Thanks, and agreed. I might have something to say about an 82mm recess in a 100mm block-work wall though...