subject: Spiral Staircase Terminology Uk Treads [print this page] Nosing: this is effectively the front edge of the tread on a staircase. It usually overhangs slightly the tread below. On a spiral staircase, or any staircase with open treads, the minimum overhang should be 16mm.
Goings: this is the measurement of the depth of the tread from front to back - usually the measurement is taken from the nosing of one tread to the nosing of the next.
A spiral staircase in the home must conform to BS5395 such that the tread goings are measured in three places along the tread - the inner going, which must a minimum of 120mm is measured 270mm in from the centre column; the centre going should be a minimum of 145mm; the maximum outer going should be less than 350mm as measured 270mm from the inside of the handrail. These are the standards which are required under Building Regulations section K1 which covers standards for stairs and ladders. The regulations state that these requirements can be relaxed where the situation dictates that it would not be possible to achieve the goings measurements when installing a spiral staircase. However in practise the spiral staircase you buy and install needs to perform its function safely and therefore we would recommend that wherever possible you stick to the requirements in BS5395.
Rise or Riser: The total rise of a spiral staircase is the total height measured from the finished floor below to the finished floor above. This measurement determines how many treads you need in your spiral staircase. The individual tread height is often also referred to as the tread riser height in this context it is the measurement of each tread height from the top of one tread to the top of the next. In a spiral staircase used domestically this should not exceed 220mm under BS5395 and K1 building regulations. Therefore if you take your total riser height and divide it by 220mm you would get the total number of risers (rounded up to the next whole number) in your spiral staircase that will satisfy the building regulations and BS5395. Unfortunately many of the continental spiral staircase kits (and quite a number sold as Custom Spiral Staircases) cannot achieve this basic requirement, as they are made to work to European standards rather than UK ones. The only way to check this is to ask the seller give them you finished floor to floor height and ask for confirmation in writing that the riser height is within the requirements of BS5395. If there is no mention of UK regulations and standards in the vendors brochure, or on their website descriptions, then always be very cautious.
Adjustment: Most spiral staircase kits have adjustable height treads, either via fixed 5mm shims or in the case of the Misterstep range via a threaded adjuster that fits between the treads. The disadvantage with using 5mm shims is that at various floor to floor heights you have to have either 2 or 3 differing tread heights within the staircase, or you have to exceed the maximum tread height of 220mm. Again some manufacturers choose not to inform customers of this, unless they are asked the question directly its a simple case of buyer beware when it comes to some spiral staircase vendors. The advantage of using a threaded adaptor between the treads is that each tread can be set to the same height, and the exact height for the total rise can be achieved without compromise. The downside is that some people find the threaded adaptor aesthetically less pleasing, whilst the shims are arguably more attractive.
