ºÃÉ«ÏÈÉúTV

When Part M of the ºÃÉ«ÏÈÉúTV Regulations: Access to and use of buildings was revised in 2004, it presented some interesting contradictions that have caused confusion for the ironmongery industry for nearly two years.

The changes made in 2004 were considerable and in many cases differed from existing procedures and the guidance provided by British Standard BS 8300 Design of buildings and their approaches to meet the needs of disabled people, which was published in 2001, and a number of other documents.

Thankfully the discrepancies have been cleared up in amendments to Part M and BS 8300 (see overleaf). During the past two years, task groups, which have included industry and client representatives, have met to consider the implications of the clash in rules and guidance and meetings have been held with the ODPM.

The British Standards Institution committee responsible for revisions to BS 8300 agreed to produce a set of amendments to the 2001 edition. The ODPM then agreed that these amendments would be incorporated into a technical memorandum regarding Part M that will be issued and published on its website.

The amendments to BS 8300 and the technical memorandum will clarify three areas in particular:

Door operating forces

The 2004 edition of Part M stipulated a maximum opening force for doors on accessible routes of 20 N. This was approximately 50% lower than what had previously been considered the norm.

Unfortunately it was not possible to provide mechanical door closing devices that enabled the door to operate within this constraint and, at the same time, meet fire requirements for self-closing doors as laid out in BS EN 1154 Controlled door-closing devices.

anecdotal evidence suggests that a 20-point difference in LRVs is an acceptable minimum for large areas

The amendments to BS 8300 and the technical memorandum now stipulate a maximum opening force of 30 N when measured at 0° (closed) and 22.5 N when opened between 30° and 60°.

The changes mean it will be possible to use a power three closer (the minimum power required to allow CE marking of closing devices for use on fire doors). This meets Part B requirements for door leaves wider than about 900 mm.

It is possible for closing devices with an efficiency of 55% to pass BS EN 1154. However, extra-performance closers, with an efficiency of more than 65%, will need to be selected for all situations where fire doors are fitted on accessible routes. The industry will need to develop a terminology for these extra performance devices.

At the project specification stage, consideration has to be given to all components of a door set that can increase the force required to open and fully close a door. Hinge friction, latch bolt resistance and air pressure differentials will, for example, affect both fire and non-fire doors. Door sets designated as fire/smoke resistant are subjected to the additional burden of hot/cold smoke seal resistances and, crucially, the spring "resistance" of a mechanical door closing device. Doors on accessible routes should be provided with:

n Hinges that perform better than the lowest friction requirements of BS EN 1935:2002 - this is 4 N per hinge maximum. High performance hinges that contribute less than 1 N friction per hinge are available.

• Latches that perform better than the lowest resistance class of BS EN 12209: 2003 - this is 15 N.
• Door seals particularly for fire and smoke protection, should introduce the minimum resistance possible consistent with their effective operation.

There has been some debate about the appropriate level of contrast between ironmongery and other building elements such as doors and walls. The contrast has to be sufficient for partially sighted people to easily identify handrails and door handles.

during the past two years task groups have met to consider the implication of the clash in rules and guidance and meetings have been held with the odpm

Visual contrast is determined by using light reflectance value (LRVs) to measure the perception of difference between two elements of a building such as ironmongery and door faces or handrails and walls. An LRV is the total quantity of visible light refracted by a surface at all wavelengths and directions when illuminated by a light source.

In the 2004 revision to Part M visual contrast was required to be a difference in LRVs of more than 30 points. The amendment to BS 8300 and the technical memorandum propose that research-based evidence for the 30-point figure is limited and that anecdotal evidence suggests that a 20-point difference in LRVs is an acceptable minimum for large areas.

Last month the Guild of Architectural Ironmongers published research by Reading University that suggested that an LRV difference of 20 points is acceptable in identifying lever handles and flat samples of typical ironmongery on doors.

More details regarding LRVs and the alternative methods available to measure them are given in the amendment to BS 8300.

Handrail dimensions

BS 8300: 2001 specified a diameter of 40-50 mm for handrails, but changes to Part M published early in 2004 stipulated a diameter of 40-45 mm. The recommendation in the amendment to BS 8300 is that "a circular handrail should have a diameter of at least 40 mm, but not greater than 50 mm". There is also text suggesting that for some disabled and elderly people a smaller diameter handrail is easier to grip.