Now more than ever, the building code forces us to study the technical details in all our staircase designs. Our design guide helps you to navigate through the list, so that your stair is up to date with the law.
The minimum headroom for any stair is 2000mm. It's listed under a section of the code relating to ceiling heights. Headroom is a common breach of the code and one that is due only to a lack of technical understanding.
For instance, when the staircase is drawn at say 1:100 scale on the first floor plan, the headroom on the stair is often deemed to be acceptable by the designer by counting down from the top of the stair the number of risers to the point where the stair disappears under the floor. Say this occurs on the third riser and the stair has a total of 16 risers. The designer then calculates 13x the estimated riser height of the stair. This is incorrect. The calculation should be 12x the estimated riser height of the stair because the stair is only 12 risers down at that point.
Other common problems when calculating headroom are, forgetting to allow for the depth of ceiling. In other words the designer calculates that the headroom beam crosses the stair at no 3 riser, the estimated riser height is 180 making the height at no 3 riser 540mm, the floor to floor height is 2750, and therefore by deducting 540 from 2750 the headroom height is 2210. That's fine, except there's no allowance for the depth of ceiling. So then deduct another 275 for the ceiling depth and all of a sudden there's a problem. There are other common mistakes made when calculating headroom but we can't list them all. If in doubt call one of our consultants. Make sure you get it right first time.
We know that every square metre of space in a house is very valuable and many designers like to allocate as much space as possible to living areas. Stairs are probably the most used thoroughfare in any two-story home and our experience tells us that customers can be greatly disappointed by a staircase that is sparing in width. Width becomes an issue particularly where winder steps are involved and all winder steps seem steeper as the stair gets narrower. This even applies to our StepSure system. Unfortunately traditional winder steps also become unusable the wider the stair gets because the steps become too big and the walking line becomes uncomfortably large. This is not the case with StepSure winders; they remain the same regardless of the width and always with greater comfort. We recommend a minimum width of 900 mm for domestic stairs and wider if possible.
Remember when drawing a stair on plan, if you specify the stairwell width to be 900 mm the stair will be up to 100 mm less than that in clear width. This is because other stair components such as newel posts, handrails and cappings encroach on that clear space. Again our consultants are always available should you require assistance in this area.
Please remember that a low riser height or a wide step on their own do not automatically make for a comfortable walking stair. The combination of the riser height and going (width of step from nosing to nosing) is what counts. If for instance you have a 160 mm riser height and a 240 mm going, the stair would be almost un-walkable. On the other hand if you have a 160 rise and a 280 going then the stair would walk beautifully. So it's all about ratios and combinations. A rise of 190 combined with a going of 240 whilst quite steep, is safe and comfortable to walk on. A stair with a 280 going and a 190 rise is not.
When specifying stair components such as newel posts for instance, don't expect the posts that have been specified at '100mm x 100mm turned' to be finished that size. 100mm x 100mm is a sawn size. That means that when the manufacturer buys the material in a raw state it is approximately that size, but after being machined or dressed will be reduced by up to 10%. So a 100 x 100 post will end up being 90 x 90. This should be specified in the stair builders quote, but even if they nominate finished sizes some tolerance should be allowed for.
It is important to keep in mind that when ordering a stair or anything made of timber, that timber is a natural material and the colour does vary. Total colour match will never be achieved. An attempt should be made by the manufacturer to minimise colour discrepancy and total mismatch, but sometimes this is very difficult. So colour differences are a part of the nature of timber, the same as differences in grain patterns and should be admired as a part of the character of the overall product.
Balustrading and Handrail Heights
Balustrading and handrail heights are set minimums in the Building Code of Australia and therefore must be adhered to. It is important to note that when specifying these heights on plans that finished floor surfaces including carpet be taken into account. The stair manufacturer should be well aware of the potential for disaster when such tolerances haven't been allowed for, but now so are you.
Geometric or Curved Stairs
These stairs are usually designed with one thing in mind and that is impact. Geometric stairs usually dominate an entrance hall and are there specifically for the dramatic first impression they create. A couple of tips for designing these stairs. Firstly try to avoid landings in a geometric or curved stair. Also try to avoid a pitch or radius changes at any point. All of these things have an effect on the aesthetics of the stair by corrupting the flowing lines that a stair of this type should feature. If assistance is required when designing a geometric stair of any type, just call one of our consultants. They'd be only too pleased to help.