Factors affecting the usability of stairs

Dr Michael Wright21st October 2002

Contents of presentation

Current UK regulations

Our research

Our results and recommendations

What are the current UK requirements for stairs?

There are two Building Regulations which cover stair design

• Part K: Stairs, ramps and guards

• Part M: Access and facilities for disabled people

Approved Document K Institutional and assembly stairs

Maximum rise = 180 mm

Minimum going = 280 mm

550 mm 2Rise + Going 700 mm

Minimum Headroom = 2 m

For maximum rise for stairs providing the means of access for disabled people reference should be made to Approved Document M

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Going (mm)

Ris

e (

mm

)

Going plus twice rise = 700 mm

Going plus twice rise = 550 mm

Approved Document K Institutional and assembly stairs - continued

No minimum width recommended

Maximum length of flight is 16 risers

Level landings at top and bottom of every flight (at least as long as the narrowest part of the flight)

Stairs narrower than 1 m should have at least 1 handrail, otherwise a

handrail on both sides(mounted between 900 mm and 1000 mm from pitch line)

Approved Document K Institutional and assembly stairs - continued

Flights and landings should be guarded at the sides if there are

two or more risers

If children under 5 years might use the stair the guarding should

not be readily climbable, nor should a 100 mm sphere be able to

pass through the guarding.

The height of the guarding should be at least 900 mm.

What can be done to make stairs easier to use?

The regulations in Part K were drawn up with an “average”

user in mind.

Part M deal with “disabled people” which means, according to

the regulations, someone who has

“(a) an impairment which limits their ability to walk or which

requires them to use a wheelchair for mobility, or

(b) impaired hearing or sight.”

Approved Document M External Non-Dwelling Stairs - disabled people

Top landing has corduroy tactile surface, 400 mm from top nosing to

1200 mm from top nosing

Nosings distinguishable through contrasting brightness

Unobstructed widths of at least 1 m

Rise between landings a maximum of 1.2 m

Maximum rise = 150 mm

Minimum going = 280 mm

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180 200 220 240 260 280 300 320 340 360 380 400

Going (mm)

Ris

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Approved Document M External Non-Dwelling Stairs - continued

Risers are not open

A flight of 2 or more risers should have a suitable continuous handrail

on both sides

Handrail is at least 900 mm above the pitch line

Each handrail should extend at least 300 mm beyond the first and last

nosing

Profile of handrail is suitable (shows a circular one, 45 mm to 50 mm diameter)

Approved Document M Internal Non-Dwelling Stairs - disabled people

No requirement for provision of tactile surface

Nosings distinguishable through contrasting brightness

Unobstructed widths of at least 1 m

Rise between landings a maximum of 1.8 m

Maximum rise = 170 mm

Minimum going = 250 mm

Less generous due to more onerous design constraints

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Going (mm)

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Approved Document M Internal Non-Dwelling Stairs - continued

Risers are not open

Same requirements for suitable handrail

Exceptionally the provisions of the rise of a flight may be varied if

particular storey heights or the need to gain access beneath an

intermediate landing dictate, or the additional length of the stair has

unreasonable effects on usable floor areas.Then use AD K

So, what is there left to do?Some groups have not had their needs addressed, and there are other features which are not dealt with in the Approved Documents, for example not all of the following groups are explicitly considered;

less able stair users: elderly (over 75 years of age), ambulant disabled, visually impaired, elderly visually impaired (over 70 years of age);

people of extreme sizes: tall people (above 95th percentile for height), heavy adults (above 95th percentile for weight), small adults (below 5th percentile for height), children.

What was done?

These groups were presented with 5 different stairs, they used them, and

in focus groups we collected their opinions on every design feature they

had experienced. These were compared with “average” subjects, those

who fall within 15% of the mean weight and height of the adult population

in the UK, one male group and one female group.

This work was funded by the Office of the Deputy Prime Minister

Dimensions

Rise

Going

Pitch

Headroom

Going

Is perhaps the most influential of all stair dimensions Previous research has shown that larger goings are

preferred

Subjective questions I would feel safe having this stair in my home I had to pull myself up the stair using the handrail I hardly had to look at the steps as I came down the stair There was enough room to put my feet comfortably on each step I relied on the handrail to support me as I came down the stair I felt safe walking up the stair I would not like to negotiate this stair in the dark I had to turn my feet sideways to place them on each step I had to concentrate all the time when climbing down the stair I could hurry / rush down the stair if I had to While descending I had to walk with my body twisted I felt that there was not enough room for my feet It would have been easy to fall down the stair Its easy to mis-judge a step when climbing down I felt safe walking down the stair

Subjective responses

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150 175 200 225 250 275 300 325 350 375 400 425

Going (mm)

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Left Axis

Q2 mean rank

Q5 mean rank

Q7 mean rank

Q8 mean rank

Q9 mean rank

Q11 mean rank

Q12 mean rank

Q13 mean rank

Q14 mean rank

Right Axis

Q1 mean rank

Q3 mean rank

Q4 mean rank

Q6 mean rank

Q10 mean rank

Q15 mean rank

Q15: I felt safe walking down the stair

No difference in opinions from 275 mm onwards

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Going (mm)

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Left Axis

Q2 mean rank

Q5 mean rank

Q7 mean rank

Q8 mean rank

Q9 mean rank

Q11 mean rank

Q12 mean rank

Q13 mean rank

Q14 mean rank

Right Axis

Q1 mean rank

Q3 mean rank

Q4 mean rank

Q6 mean rank

Q10 mean rank

Q15 mean rank

Subjective responses

0%

10%

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60%

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Going (mm)

Pe

rce

nta

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of

sh

oe

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90th Percentile

10th Percentile

Proportion of shoe overhang

Going

Is perhaps the most influential of all stair dimensions Previous research has shown that larger goings are preferred This preference was confirmed within this study

What goings were preferred?

298 mm 250 mm 220 mm 300 mm 250 mm

Going

Users found it difficult to consider going in isolation

What about rise and going combinations?

298 mm 250 mm 220 mm 300 mm 250 mm ?x222 mm 185 mm 186 mm 200 mm 163 mmgoingrise x

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Going (mm)

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Headroom

1948 mmdown stand

2167 mmparallelx ?

Conclusions

Larger goings are preferred, no smaller than 250 mm Going cannot be considered in isolation A rise of 200 mm is acceptable with the right going May need to limit pitch to about 37°

Tall users are used to restricted headroom at 2000 mm Parallel soffits can feel claustrophobic if they extend too far

along the flight.

Handrails

Purpose of handrails

Guidance - This is especially true for people who are visually

impaired, who tend to use the handrail as a guide Support

- This is especially true for people who have difficulty walking, or are old, who can use the handrail to keep balanced or to pull themselves up when climbing

Stability- In the event of a fall or a wobble, a handrail can help

stabilise the user and may help prevent a serious injury

Areas to be covered

Shape Size Continuity and gap Overhang Height Number

Shape - pigs ear

x

Shape - traditional

?

Shape - circular, oval, flat

Size 50 mm diameter

50

Beyond 95th percentile grip 46 mm Difficult to get thumb around

Size 30 mm diameter

Beyond 5th percentile grip 32 mm Cannot get fingers past supports

30

Size

463230 50

x x

5th to 95th percentile grip for UK adult population

Size - circular, oval, flat

May be better consider perimeter for other acceptable shapes

Perimeter should be between 100 mm and 150 mm

Continuity and gap

50 mm too small (50 mm to 60 mm recommended in BS8300) 100 mm too large 75 mm preferred Should continue throughout flight

Overhang

Indicates start of flight in descent Used to pull user up last step Should be at least 300 mm

At the top

Indicates end of flight in descent Less necessary than at top Could use alternative termination Clothes might catch on open ends

At the bottom

Height

900 mm - 1000 mm preferred Children choose higher handrail

Number

Two handrails preferred Provide choice in descent 800 mm to 1000 mm apart

Some felt unsafe with no handrails Some need handrail to climb

Conclusions

Two handrails 800 mm - 1000 mm apart 900 mm above pitch line Handrails should extend beyond flight, especially at the top 75 mm wall gap Diameter between 32 mm and 46 mm or Perimeter between 100 mm and 150 mm Circular oval, and flat shapes work best

Other design features

Landings (for resting) Winders Open risers Overhanging nosings Hard Surfaces Designation Contrasting nosings

Landings Visually impaired users did not like the landings, since the hardest

part of the stair to negotiate was the transition to or from the level and this had to be performed more than once with a landing.

Landings Landings dictate where a rest can occur The height of the landing did not seem to be an issue When comparing the same overall length of stair, a larger going of

300 mm was preferred over a 900 mm landing in the flight

Winders Difficult to maintain constant going between steps, which may lead to

confusion Difficult for most people to negotiate, especially those with poor vision

Open and partial risers, overhanging nosings

Full Full PartialFull Open

Open risers disliked by many users, impossible for some users Traditional nosings can be just as bad

x x x

Hard surfaces Hard surfaces make noises, which is disconcerting for some users Can cause more serious injuries on collisions

x x xCarpet Metal TileLinoleum Wood

Designation

Colour and shade Projecting handrail Tactile

Most users did not notice the designation without prompting The handrail designation was considered to be the best approach

Contrasting nosings Did help indicate the nosings in descent (painting is sufficient) No one wanted them in their home

Avoid busy or patterned carpet Provide good lighting, preferably from two sources

Conclusions

Larger goings preferred over landings Winders to be avoided unless adequate handrails supplied Open risers should be avoided Traditional nosings could cause problems for some users Avoid hard surfaces Extended handrails are the preferred method of designation Provide adequate lighting Avoid busy or patterned carpets