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Staircase design

https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Parana_pine_truck.jpg/800px-Parana_pine_truck.jpg

Parana pines, much used in staircase construction

In terms of embodied energy the use of timber in staircases is far better than metal. However the timber should be sustainably sourced and be FSC or PEFC woodmarked. One of the traditionally favourite timbers for the manufacture of staircases has been parana pine (Araucaria angustifolia) from Brazil but this is now critically endangered.      see more on Parana pine

A fair number of timber merchants and joinery manufacturers in the UK are still claiming to be supplying sustainably sourced parana pine staircases. However the scientific literature from groups such as Geographical Paper No.180 by J.V.M. Bittencourt , University of Reading, shows the devastating manner in which parana pine has been over harvested and it is difficult to imagine how any real volume of the timber can be available on a sustainable basis.

It is on the IUCN Red List of Threatened Species as a critically endangered species.

‘Since 2001 there has been an official Brazilian ban on log exports of this species. The Brazilian Government is also promoting several initiatives to protect Araucaria genetic resources’


Although many staircases are now supplied as whole systems which are modified for the particular purpose, there are still many occasions when it may be better to revert to traditional joinery, metalwork or masonry. This is particularly true where repairs, changes or extensions are being made to a house or traditional features require matching. The exception to this is spiral stairs where it usually makes sense to utilise a prefabricated system.

Staircase design

The stairs always seem to take up more space than you first imagined (often around 8% or more of the total floor area when you include the associated landings) so it is good to work out a rough size and configuration at an early stage of designing a house. This is particularly true for the relationship of circulation space between different floors. There are several factors which influence the design of stairs:

• the vertical relationship of the landings the stairs serve     see more

One straight flight
At its simplest this involves a straight flight with a landing area at the top and bottom. This is usually the cheapest type to build and is most economical in terms of floorspace, taking up about 10 m² in total (i.e. both floors). Because the lower and upper landing are so far apart horizontally it may be difficult to fit in with the room layout. This is the layout generally used when the lower landing is in the hall or living room near the front door.

The spaces around, under and above stairs can range from grubby little cupboards to opportunities to display all kinds of beautiful artefacts such as plants, pictures works of art, creative lighting etc. This is more true with open tread and spiral stairs where the spaces are more visible.

Not that there is anything wrong with cupboards under stairs but given the non-rectangular, somewhat sculptural shape of stairs it provides a chance to be creative. With long straight flights it may leave space beneath the stairs for a doorway through to another room or a small space for a desk, stereo etc.


Half landing return.

Because of space configurations there is often a half landing and then a turn of 180°.

This allows the top landing to be vertically above the bottom one which may be useful with some types of room layout, especially for external stairs. It’s more expensive to build and takes up about 14 m² of floor plan. It may also be more difficult to arrive at a good design for the spaces below the stairs so it can look a bit poky.


Dogleg

Alternately a turn of 90° may work and this configuration can be particularly useful if you are wanting to link lower and upper floors where the circulation spaces don’t match easily, for instance if you are linking together two existing adjacent properties. Adjusting where the half landing occurs on the stairs can also be used to make adjustments between irregular floor levels. Takes up 12 m² of floor plan.


the aesthetic value of the stairs      see more

Stairs can have several aesthetic components:

They can be beautiful in a purely sculptural way, especially regarding the materials they are made of.

They give a different vertical quality to a space, especially when there is some visual connection between the two storeys they serve:

The book ‘A Pattern Language‘ goes into this in one of its patterns called ‘Staircase as a stage’

“A staircase is not just a way of getting from one floor to another. The stair is itself a space, a volume, a part of the building; and unless this space is made to live, it will be a dead spot, and work to disconnect the building and to tear its processes apart”

The point is also made that people often like to sit on stairs and may use stairs to make an ‘entry’ into a room. So the advice goes:

“Place the main stair in a key position, central and visible. Treat the whole staircase as a room (or if it is outside, as a courtyard). Arrange it so that the stair and the room are one, with the stair coming down around one or two walls of the room. Flair out the bottom of the stair with open windows or balustrades and with wide steps so that people coming down the stair become part of the action in the room while they are on the stair, and so that people below will naturally use the stair for seats.”

Stairs on an outside wall can be lit by a tall window: the Victorians often commissioned stained glass work for these. Half landings can incorporate areas to place objects of beauty or window seats. Pattern Language suggests a window affording a Zen view. Landings can be very interesting areas especially if they are part of a gallery which overlooks rooms below or a courtyard.


the cost which can vary enormously     see more

At the cheapest end is the factory made straight flight of timber stairs with closed risers. At the other end is almost anything you can imagine


the type of construction and materials     see more

The main structure of the house may suggest the type of stairs which seem best suited. For instance a very heavy masonry structure may be able to support cantilevered treads. Open risers are often used on modern houses. Timber houses would seldom use masonry stairs for structural reasons.
Stair treads obviously need to be hard wearing and it is almost as if stairs have been divided into two types historically: ones which were meant to be carpeted and ones which were meant to be left exposed.

The carpeted ones (usually with timber risers) were normally with softwood treads which wear down if not covered.
The exposed ones tend to be mainly hardwood but also stone, concrete, terrazzo, steel (usually with a covering such as cork, rubber, timber etc.).

If you are using timber for the stairs then this is an opportunity to show off some of our beautiful native timbers. Because staircases use a relatively small volume of timber it is possible to splash out and use the best. Most people know of ash and oak but there are several more exotic species in terms of colour and grain. Native cherry has slightly pink streaks with yellow markings. Native yew is very exotic in terms of its rich red/brown grain mixed with cream. The fruit woods are light in colour and elm has a rich and charming grain. Alder can have strong streaks of red if treated with oil.


the possibility of stair lifts / lifts     see more

With the growing awareness of Lifetime Homes there is a strong case for considering how stair design might relate to lifts and stair lifts, not necessarily for your own use but also as a way of making a house easier to sell in the future or for the use of a disabled relative. With an ageing population, this will become an increasingly important issue.

The section on Disabled Access indicates how lifts might relate to stairs and landings. In the case of stair lifts there is a case for designing stairs so they may take a stair lift at a later date. This involves the width of the stair, structural support for the lift, adequate space on landings and power supply. It may also have a bearing on the design of service ducts


the Building Regulations (England)

The regulations, (mostly Part K), have a lot to say about stairs.

Below are extracts from the Building Regulations where stairs in houses are termed ‘Private stairs’

Because the relationship between the rise and the going is quite complicated there are 2 methods of achieving the correct result but they both rely on the fact that the pitch of the steps must not be greater than 42°.

This is how straight stairs are measured:

 

The rise and going are limited as follows
RISE GOING
minimum (mm) maximum (mm) minimum (mm) maximum (mm)
150 220 220 300

The two ways to calculate stairs are:

  • The maximum rise for steps is 220mm and minimum going is 220mm (but of course with the added proviso that it will not be steeper than 42°)
  • The other way is to make sure that the relationship between the dimensions of the rise and going is that twice the rise plus the going (2R + G) should be between 550mm and 700mm.

Straight stair calculator (England)

The live spreadsheet below works on the assumption that you have a fixed floor to floor dimension (total rise) but you may want to vary the number of steps and their size and the slope. You can input the number of risers you want and their goings and the spreadsheet then checks whether they conform to the Building Regulations. Enter your guestimate values into the green boxes and then the red text comments indicate whether the necessary conditions are met. Other values such as riser height and pitch get calculated. If the conditions are not met you need to try different goings and risers.
This essentially works for a straight run of steps but it also works if you have a half landing (a dog-leg in the stairs). The half landing can simply be considered as a square step. If you want to use kite winders to turn a corner then they should conform to the rules for spiral stairs.

Notes:

  1. Stairs are limited to 36 consecutive risers in a flight unless there is a change in direction. See para 1.14 in the Approved documents.
  2. Risers are not allowed to exceed 220mm
  3. It is important to work to 0.1 of a mm.  (or better) because cumulative error on many steps can become significant
  4. The greater the going the shallower the pitch of the stairs. You can’t have a combination of the maximum risers (220) with the minimum goings (also 220). It makes it too steep (over 42 deg). Longer goings make for shallower but longer stairs.
  5. If this result does not fall within 550-700 try adjusting the risers (via the number of risers) and the goings. The formula comes from the Building Regulations.
  6. if this is above 42 degrees then try increasing the going (or increasing the number of risers to make them smaller)
  7. The total length is the horizontal distance from the nosing on the top landing to the position on the lower landing directly below the lowest nosing. See diag. below

The 2000mm headroom rule can be reduced under certain circumstances for loft conversions. (see part K , page 8)

These calculations give you results as if there were no nosings on the treads. That is fine because you can simply add nosings to the steps afterwards without altering the basis of the calculations. However doing so will affect two things: both the headroom and the lower landing length will be reduced marginally.

The landing is determined by the regulations.

Headroom (with exemption for loft conversion)

A headroom of 2m is adequate on the access between levels (see Diagram 2). For loft conversions where there is not enough space to achieve this height, the headroom will be satisfactory if the height measured at the centre of the stair width is 1.9m reducing to 1.8m at the side of the stair as shown in Diagram 3.

10 comments to Staircase design

  • bobthebuilder

    Thanks Gideon, British Standards tend to disappear pretty quickly when they are made freely available on the net.

    You have to spend the best part of £100 to buy this one.

    This all goes back to the Thatcher years when “there is no such thing as society” meant that agencies such as British Standards got privatised. This was theft of public information into the private realm.

    But what do you expect from that type of government.

  • Gideon viljoen

    Hi – this is brilliant. THANKS!

    Your link to the BS5395 doc doesnt work though..

    Best
    Gideon

  • M Hopper

    A straight staircase against right hand wall (going up)ground floor to first floor (1970s house)eight feet floor to ceiling, 14 steps, need to know minimum height from front of step to ceiling.

  • Vivienne Mitchell

    Has anybody got any information on who can come and build me a helical staircase or two, preferably good and cheap. Lincolnshire area. many thanks.

  • Fadi

    Hi,
    Thank you for your post. I am designing a helical staircase for a university project, it is composed of 3 parts that get steeper. The risers are respectively 90mm, 105mm, 129 mm. Unfortunatly, if I refer to Part K, the minimum rise should be 150mm. Des this vary BS 5395-2 ? Is there a minimum rise value at all for helical staircases?

    Thank you

  • bobthebuilder

    Hi Carl,

    Not quite sure what you mean by deviation.
    The maximum rise for steps is 220mm and minimum going is 220mm
    But if you mean ‘can you stretch the rules a bit’ then the answer is maybe. You can sometimes get what is called a ‘relexation’ of the building regulations. A relaxation is most often given when changes are being made to existing buildings when a slight ‘bending’ of the rules might lead to some other major gain. E.g. headroom is sometimes relaxed.

  • carl jenkins

    Is there a maximum permissible deviation for the dimensions of each tread / riser?

  • Graeme

    Hi, iwould like to find out about the requirements for supporting a double winder newel post fir stairs leasing to loft, by suspending from a structure above? Supporting from below places the newel right in the middle of the existing srairs. any advice on this approach? Thanks

  • Stephanie

    Thank you so much for this spreadsheet!

  • Mike Earley

    The stair spreadsheet was just want I needed. Everything is included. Perfect – thank you

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