Manual of Purpose-Made Woodworking Joinery

100 Designing and making stairs to current building regulations

should be constructed so that a 100mm diameter

notional sphere could not pass through the open risers.

Fixed ladders

A fixed ladder should have fixed handrails on both

sides and should only be installed for access in a loft

conversion – and then only when there is not enough

space without alteration to the existing space to

accommodate a stair which satisfies the criteria already

covered for Private Stairs. It should be used for access

to only one habitable room. Retractable ladders are

not acceptable for means of escape. For reference to

this, see Approved Document B: Fire safety.

Handrails for stairs

Figures 6.24(a) and (b): Stairs should have a hand-

rail on at least one side if they are less than 1m wide

and should have a handrail on both sides if they are

wider. Handrails should be provided beside the two

bottom steps in public buildings (Category 2 Stairs)

and where stairs are intended to be used by people

with disabilities. In other places (Category 1 Stairs),

handrails need not be provided beside the two bottom

steps – as indicated in Figure 6.24(b).

maintained. Where a stair consists of straight and

tapered treads, the going of the tapered treads should

not be less than the going of the straight flight.

Note that BS 585: Wood Stairs Part 1: 1989:
Specification for stairs with closed risers for domestic use,
including straight winder (tapered tread) flights and
quarter- or half- space (half- turn) landings is given in
AD K1 as a British Standard which will offer reason-
able safety in the design of stairs.

Alternating tread stair

Figure 6.4: This type of stair is designed to save space
and has alternate handed steps with part of the tread
cut away; the user relies on familiarity from regular use
for reasonable safety. Alternating tread stairs should
only be installed in one or more straight flights for a
loft conversion and then only when there is not enough
space to accommodate a stair which satisfies the criteria
already covered for Private Stairs. An alternating tread
stair should only be used for access to one habitable
room, together with, if desired, a bathroom and/or a
WC. The WC must not be the only one in the dwell-
ing. Steps should be uniform with parallel nosings. The
stair should have handrails on both sides and the treads
should have slip- resistant surfaces. The tread sizes over
the wider part of the step should have a maximum
rise of 220mm and a minimum going of 220mm and

Imaginary, vertical
planes formed by
pitch lines for
checking the
various 2R+G rules

270

R

Going

270

G

G

2R+G

R

R

Pitch

R

Figure 6.23 (c) Imaginary, triangular vertical planes
shown to emphasise the measuring points for minimum
2R+G (R/H pitch- line) and maximum 2R+G (L/H pitch
line) on tapered- tread stairways of 1m or more in width
(deemed length).

One handrail, Two handrails

at least, if

stairway is

less than 1m

if stairway is

wider

than 1m

Figure 6.24 (a) Handrail rules for stairs.

Bottom Steps

Figure 6.24 (b) Steps allowed in Category 1 Stairs

without handrails.