The UK’s independent authority on slip resistance

How does slip resistance and tread covering effect the safety of a stair nosing on a stairway?

How does slip resistance and tread covering effect the safety of a stair nosing on a stairway?

There has been much research undertaken into safety on stairs, since one of the many statistics established is that over 300,000 patients a year visit hospital as a result of an accident on a stair. This underlines how important it is that a stair should be made as safe as possible.

Correctly specified and installed Stair Nosings are one of the principle factors necessary for the creation of a safe stair.  Certain features of Stair Nosing and stair design help to satisfy criteria that are set out in guidelines appearing in current Building Regulatory documents. The that this article sets out to look at a slip resistance and also tread coverage.

 

III: Slip Resistance of Tread Material

Feature Summary

The upper surface of a Stair Nosing is designated the tread, as is the horizontal section of each step. On a Stair Nosing the tread needs to offer a slip resistant surface that will help prevent the incidence of mishaps when footfall is ascending or descending a stair.

The guidance for the slip resistance of Stair Nosing tread material is very much linked to that of the floorcovering on the stair case. The following Documents make reference to the slip resistance of Stair Nosing tread material and give guidelines for their performance in this regard:

  1. Building Regulation (Document M) – reference refers to BS8300 (see below)
  2. 1:2010 – Section 10.6 p14
  3. BS8300:2009+A1:2010 – Section 9.5 p26 and Annex E.5 p196
  4. BRE IP15/03 – (13)

In both cases the guidance for the slip resistance of the Stair Nosing tread is that the material used should have a ‘Rubber Boot – 95’ Pendulum Test Value (PTV) of at least 36 in both dry and wet conditions. The Pendulum test method is a standard system for the measurement of the resistance of floor covering materials. The practical problem however is that once a Stair Nosing is installed, due to the restricted width of a step’s tread, there is insufficient room for the pendulum to be swung on site. Therefore, the guideline measurement can only be achieved in factory conditions prior to any installation, and thus the measurement of used tread material on site is not possible.

(A PTV measurement of the tread material on the top most step of a stair case can be undertaken, and this may give an indication of the tread material on the other Stair Nosings on the flight, but it is no more than that – an indication).

For a used or on-site measurement of Stair Nosing tread slip resistance an additional means of measurement is with a surface roughness micrometre. The Health and Safety Executive (HSE) has established guidelines in its Slips Assessment Tool (SAT) which is a freely downloadable computer software package that allows an operator to assess the slip potential of pedestrian (walkway) surfaces. It indicates that if a material has a micro roughness reading greater than 20 µm, then it can be classified as being of ‘Low Slip Risk’.

 

Slip Potential Rz Value1
PT Value1
High Slip Potential below 10 µm 0 – 24
Moderate Slip Potential 0 – 20 µm 25 – 35
Low Slip Potential 20+ µm 36+ (minimum requirement)

1 RZV=Surface Roughness Values and PTV=Pendulum Test Values

As a consequence of the limitations inherent in the opportunity to achieve reliable on-site slip resistance measurements of Stair Nosing tread material, the current ‘best practice’ guidance is a combination of the two methods. It is recommended that specifiers, contractors and end users look to install Stair Nosings with tread material that has been independently laboratory tested to have a PTV greater than 36 and similarly a micro roughness reading of more than 20 µm – both in wet and dry conditions. It is then possible (if necessary) to use a micro roughness metre on site to re- measure the µ value and comparisons can be made to give an indication of any changes over time. Due to the variability of site conditions however it should be stressed that this is very much only an indication.

The following extract from BS8300:2009+A1:2010 – Annex E.5 p196 sums up the position:

“Where slip resistance is required for nosings and treads, the slip resistance needs to be equivalent to that expected for level surfaces. A PTV greater than 36 is considered to be suitable, as pushing and turning are unlikely on stairs. On existing nosings, the slip resistance of step nosings are generally expressed by their Rz roughness value as PTV is difficult to measure. In such cases a roughness Rz value of 20μm is recommended.”.

 

IV: Tread Surface

Feature Summary

Traditionally the Stair Nosing tread material has been contained within a shallow channel on the upper surface of the Stair Nosing carrier the carrier usually being made from aluminium, PVCu or in a limited number of cases, cast iron, steel, brass or bronze.

More recently (October 2003 – That is Mike Roys’ paper “IP5”) however work undertaken at the Building Research Establishment has concluded that the tread material should extend right across the upper surface of the Stair Nosing.

This recommendation is contained within BRE IP 15/03 which covers many aspects of stair design with respect to safety. It indicates that, particularly in descent, a person’s foot fall will usually impact at an angle on the very front of the nose (edge) of a step. The shorter the going of the tread the more likely this is to occur.

As a consequence, the improving guidance that comes from the work undertaken at BRE identifies that the most practical and safest format for a Stair Nosing tread material is for it to cover the whole of the upper surface of the Stair Nosing carrier – right up to and over the front edge.

This ensures that footfall, particularly in descent, is onto a slip resistant surface. The importance of this is heightened when the tread going is at the shorter end of the recommended design and construction dimensions.

The relevant statement in BRE IP15/03 (p6) is:

Slip-resistant nosing: The risk of slipping can be reduced if the proprietary nosing incorporates a material that has slip resistant properties at the point where contact is likely to be made………….. the slip resistant material must continue to the very (front) edge of the tread.”

By making sure the correct tread material is specified along with the appropriate all over tread coverage, it is possible to greatly reduce the risk of slips on stairs.

 

 

 

 

This article was written by Tim Hayes, Marketing Manager at Quantum Flooring. Based in Oldham, Quantum is a business that has operated in the local area north east of Manchester for over 50 years. It is a private company employing nearly 100 people. The demanding service needs of the market dictates how Quantum operates. The key underlying principles being those of LEAN, GREEN, SAFE and CLEAN. Always creating value for customers. Quantum Flooring is the brand under which Quantum offers professional flooring products to the Contract Flooring Market.

For more information about the company and on the correct specification of stair nosings please visit www.quantumflooring.co.uk

 

 

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