Design and construction of stairs and staircases

When designers are planning spaces within the home stairs are often redesigned many times before they are built. Stairs not only need to be located in an appropriate location, but they must be comfortable to use and safe for their users.

Here are 5 essential tips to ensure your stairs are designed and constructed for comfort, style & safety. Remember all items should be confirmed by referring to the latest Australian building code (BCA).

Location, location, location

Deciding on the location of your stairs needs to occur early in the design phase.

Staircase location can vary depending on your requirements but most stairs are centrally located and handy to the main entrance as well as the main living space. Note in the plan below, the orange coloured stairs are in a good central location; i.e. close to the entry and living areas. This saves travel time around the home and offers privacy to other spaces in the home. The brown coloured stairs are not in a good central location. They force people to go through the dining area and also make users spend more time getting to other areas in the house.

Stairs can take up a considerable amount of space. You may need to factor in circulation space around the stairs as well. You can safely assume that a staircase will require a minimum width of 1.1m and a minimum height of 3.5m long. In a typical Australian house is not uncommon for a staircase to be 1.4m wide x 5.9m long.

Do not forget your stair dimensions will need to be mirrored onto all floor plans.

Avoid designing stairs any narrower than 880mm wide when finished (i.e. with plasterboard on walls). Australian standards for stair construction will allow for narrower stairs but narrower stairs will be uncomfortable to use, especially if you install a hand rail or have winders.

Plan B: Efficient use of space (click to enlarge image)

If space and costs are an issue, keep your stairs simple and multifunctional. Plans A & B above show storage spaces underneath the stairs. This is common with staircase design It is done to avoid wasted space and to hide stairs that would otherwise interfere with head heights in other spaces.

If you have no choice but to include stairs in habitable areas (these are areas that require a ceiling height of 2.4m) there are a few tips from the trades you should know.

Stairs – Section Plan (click to enlarge image)

Tips from the trades

  1. Use the underside of your stair as a lighting bulkhead (See section above)
  2. Only 2/3 of a habitable room needs to have a ceiling height of 2.4 the rest can be lower (please check with the latest BCA requirements).
  3. A bathroom is not considered a habitable space and can have ceilings as low as 2.1m high (please check with the latest BCA requirements).
  4. Ensure the finished underside of your stair in no less than 2m off finished floor level near doorways.

Stair types & dimensioning

There are three types of stairs – traditional, contemporary and concrete. Variations on these are; conventional, spiral, circular and open-riser.

Types of stairs

Straight flights

The simplest form of stairs is the straight flight. These are generally built with or without landings with a maximum of 18 treads in each run. Most straight flight stairs are built against a wall or between two walls. This reduces the amount of space accommodating the stair. Mid-flight landing depths are traditionally the same width as the stair width. The BCA will allow lengths of mid-flight landings to be as little as 750mm.

No landing allowances are included in above table, if required just add a minimum of 800mm to your landing length. Also remember flights must not have more than 18 rises in one flight, landings must be added between flights.

90 degree flights

The 90 degree flight is very space efficient for small two story dwellings or town houses. The 90 degree flight is usually built against many walls meeting internal and external walls.

It is possible to change the direction of a wall and stair to follow a different angle like 30 degrees or 45 degrees.

Return flights

The return flight stair is the most common stair used in Australia for flats and houses and can include Half or Quarter landings. See stair flight drawing below. Return flights may be built as free standing but are normally built against walls (it depends on design requirements).

A traditional circular stair has treads that are cantilevered of a circular surrounding wall, this type of stair is costly and is uncommon in residential construction. Much more common is the circular stair that cantilevers it’s treads off a central load bearing post typically made of steel or timber. This type of stair requires little space and is self-supporting, but is trickier to travers than a typical straight flight for example.

Ladder stairs

There is another stair option that can take up even less space than a spiral stair, Ladder stairs. They are a cross-between a ladder and a stair and can be bought premade and folded into an attic space or you can build one as a permanent fixture, just like a stair. Ladder stairs need to be designed very well to comply with BCA requirements.

Materials

Before you choose what stair materials you will be using ensure that it is within your budge and meets your usage requirements.

Here are a few ideas on stair materials:

  • Polished concrete & tiles are hard-wearing and very modern but can be very noisy.
  • Timber is traditional but requires maintence and is noisy
  • Carpet = quiet, warm, safe and wears quickly
  • Glass = ultra expensive
  • Industrial grate

Tips

  • Riser min. and max. dimensions = 115 to 190mm
  • Run min. and max dimensions = 240 to 355mm
  • Most comfortable stair rise and run is 160 x 260mm
  • Railings must not be less than 850mm height at the nose of the stair.
  • Open risers must not allow a sphere shaped object 125mm or larger to pass through riser openings.
  • Quietest stair – reinforced concrete stair with carpet, cork, rubber or similar.
  • The safest stair is a return fight with:
    1. a handrail,
    2. carpet,
    3. risers 160mm rise x260mm run
    4. full block hand railing/balustrade