Opening and closing force guidelines

Transcription

1 Opening and closing force guidelines This document has been complied under guidance of ASDMA membership to provide information on the requirements of Part M of the Building regulations with regards to the opening and closing forces permitted to a door assembly. Part M of the Building regulations, Access to and use of buildings requires service providers to make reasonable provision for access by people to buildings, regardless of disability, gender or age, to live or work in, or use the facilities, of buildings and this, coupled with the obligations of the equality act, requires service providers and employers to have regard for potential barriers which physical building features in buildings may create. The GAI, in July 2015, issued technical briefing No 15 which has a section that outlines whether or not various documents are guidance or law. With our grateful permission from the GAI we quote that section below (Added as an image for this draft) ASDMA Opening forces document Revison C Feb 2016 Page 1

2 ASDMA Opening forces document Revison C Feb 2016 Page 2

3 Contents Section 1 : What are the guideline figures Section 2 : Factors for consideration Section 3: Factors for consideration a closer view Section 4: Setting up closers and checking opening forces Section 5: Document extracts and references ASDMA Opening forces document Revison C Feb 2016 Page 3

4 1) What are the guideline figures The maximum permitted opening forces when measured at the lever handle position in order to comply with the guidance in BS8300 and approved document M are to 30 degrees (from the closed door position) is Max 30N. However section 6.5.2, in BS8300:2009+A1:2010 NOTE 2, Where measurements cannot be taken at the leading edge, they can be taken at a point up to 60mm in from the edge and approximately vertically in line with the spindle or centre line of a pull handle in which case the opening force limits can be increased by 2n, a further 2 to 3 N can also be added due to the imprecision of the measuring device therefore the max allowance is 35N to 60 degrees = Max 22.5N ( again the same clause as noted in item 1 is allowed) therefore the max allowance is 27.5N 1.3 For a fire rated door assembly it should be noted that Building Regulations Approved Document B states that fire doors must be fitted with a self-closing device ( except for fire doors to cupboards and service ducts which are normally kept locked shut) and, based on BS EN 1154, which requires a minimum of power size 3 fitting to a fire door giving a minimum closing force of 18Nm ASDMA Opening forces document Revison C Feb 2016 Page 4

5 2) Factors for consideration There are a number of factors that will affect the forces on site and these are listed, but not limited to, those noted below:- 2.1 Seal type and orientation 2.2 width 2.3 Closer type and efficiency 2.4 Hinge resistance 2.5 Air pressure 2.6 Site installation and ongoing maintenance 2.6 Smoke control doorsets 2.7 Acoustic doorsets ASDMA Opening forces document Revison C Feb 2016 Page 5

6 3) Factors for consideration - a closer view 3.1 Seal type and orientation Smoke, acoustic and privacy seals around the perimeter of the door will affect the opening force due to the friction resistance they produce Brush or blade type seals, which are typically fritted In swipe/wipe (see fig 1) mode against cold smoke and acoustic penetration provide the biggest resistance and it is therefore unlikely that smoke seal or certain acoustic door assemblies will maintain the minimum opening force identified in Document M Frame Seal Fig 1. Swipe/wipe mode Compression seals that are generally fitted on the face of the doorstop (see fig 2) produce less friction than seals in swipe/wipe mode and therefore are subject to lower opening forces Frame Seal Fig 2. Compression mode Meeting stiles of pairs tends to cause the biggest area of concern as the modern requirement is for square meeting stiles to be employed which usually means the use of seals in swipe/wipe mode (see fig 3) and the forces created here are unlikely to maintain the minimum opening force identified in Document M. ASDMA Opening forces document Revison C Feb 2016 Page 6

7 Seal Fig 3. Meeting stile Swipe/Wipe mode One possible solution is to incorporate a surface mounted astragal with a compression seal at the meeting stiles (see fig 4), but this is far from ideal, requiring the use of door selectors, additionally it does create other problems where occupants try to open both doors together. Astragal Seal Fig 4. Meeting stile Compression mode 3.2 width leaf weight, height and width will have an effect on the opening force. To achieve optimum efficiency leaves should be between 926mm and 950mm wide. Weight, height and width are, however, less significant factors than, for example, the quality of the hinges 3.3 Closer type and efficiency Probably one of the most important of all factors is the efficiency of the closer, all fire rated doors are required to be fitted with a controlled closing device (except those designated as fire door keep locked see section 1.3) basically a door closer(this ensures the door is in the correct position to provide fire rating as required, as you can imagine a closer is constantly applying a force to keep the door in the closed position, therefore we must overcome this force in order to open the door, this is why the efficiency is such an important factor of the closer. Closers with higher efficiency provide less resistance (65% efficiency or better is essential) and as a result they require less force to open. The set-up of the closer is also very important as even a high efficiency set incorrectly will exceed the maximum opening force. Section 4 advises on the correct set up of the closer. ASDMA Opening forces document Revison C Feb 2016 Page 7

8 3.4 Hinge resistance Hinges of good quality and with low friction washers will assist in reducing the effect on opening forces but it is generally considered that the actual results of this are fairly negligible. 3.5 Air Pressure Air pressure can be a major factor which impacts on the opening force and, although this should be understood and taken into account when measuring on site, it is impossible to comment on the amounts of pressure that are prevalent in all buildings. 3.6 Site installation and ongoing maintenance Installation will also contribute to the opening force, a well installed door assembly that is square and plumb with the correct 3mm gaps between door and frame around the jambs and head will provide less resistance than a badly fitted door with tight gaps causing more friction resistance to open the door. Similarly, with an ongoing maintenance regime in place, the fit of the door will be regularly monitored with parts replaced or maintained as per the manufacturer s recommendations and or warranties. 3.6 Smoke control doorsets Approved document B requires that certain door assemblies meet smoke control requirements and in order to do this the doorset will require seals to be provided at the jambs, head, and in the case of pairs, the meeting stiles. It should be noted that the threshold does not form part of the calculation for the UK smoke leakage requirement of 3m 3 /mtr/ hour. The provision of seals for smoke leakage are considered in section 3.1 of this document. 3.7 Acoustic doorsets Approved document E sets out the requirements for the acoustic requirements of a building and in order to do this the door assembly will require seals to be provided at the jambs, head, and in the case of pairs, the meeting stiles. For door assemblies with lower acoustic performance less seals tend to meet the requirement and there is less impact on the opening forces but the higher the acoustic performance the amount of seals can tend to increase and thus cause increased resistance and higher opening forces. Acoustic door assemblies will generally have some form of threshold sealing mechanism and these again can have an impact on the opening forces. There are generally two options for sealing at the threshold and figs 5 and 6 noted below illustrate the two most popular options name bladed seals and dropseals ASDMA Opening forces document Revison C Feb 2016 Page 8

9 Fig 5 shows a typical bladed seal at the threshold that may or may not incorporate a metal or timber threshold fitted to the floor. This type of seal will engage with the threshold when the door is in the closed position and can, therefore, have a similar effect to swipe /wipe mode seals as illustrated in fig 1. and fig 3. in that the opening force will generally increase Frame Seal Threshold fitted to floor and or floor finish Fig 5. Threshold sealing system with swipe/wipe blade Fig 6 shows a typical dropdown seal at the threshold that may or may not incorporate a metal or timber threshold fitted to the floor. This type of seal will engage with the threshold and or floor finish when the door is in the closed position and will retract back up into the door once the door commences its opening sequence so will, therefore, have a similar effect to compression mode seals as illustrated in fig 2. and fig 4. in that the opening force will generally be lower Frame DropSeal Threshold fitted to floor and or floor finish Fig 6. Threshold sealing system with dropseal The provision of seals in the door frame and meeting stiles for acoustic door assemblies are considered in section 3.1 of this document ASDMA Opening forces document Revison C Feb 2016 Page 9

10 4 Setting up closers and checking opening forces INITIAL SETUP For fire resisting doorsets install and adjust to ensure minimum 18Nm (power size 3) and that the door closes from any angle and over any latch that may be fitted. Open the speed and latching valves fully. Open the door and allow the door to close at a rate of 1 degree / second whilst holding the force measuring instrument against the face of the door and moving it back in time with the door. This will give a value N which is the Newton force exerted when the door closes e.g.20n. To calculate the closing force, simply use the following: - N(c) = The Newton force exerted by the closer when the door closes e.g. 20N m = The distance from the hang edge of the door to the point where the force measuring instrument was located e.g m The equation is as follows: - (N(c) x m = Nm. e.g. 20 x = 17.68Nm You may need to adjust the closer in order to achieve 18Nm several times but once each closer is set up no further adjustment will be required to the unit unless a greater speed is required to enable the door to latch. ASDMA Opening forces document Revison C Feb 2016 Page 10

11 5 Document extracts and references 5.1 BS EN 1154: 1997 Building hardware- Controlled closing devices requirements and test methods. Annex A to BS EN 1154 states that due to their low closing moments door closers size 1 & 2, without adjustable closing force, are NOT considered suitable for use on fire/ smoke door assemblies. closers with adjustable closing force shall be capable of adjustment at least to power size 3. A power size 3 closer is required to exert a minimum closing force of 18NM, or 21.2N closing force when measured from the handle of a standard 926mm wide door. However, fitting door closing devices greatly disadvantage people, including children, with a wide range of disabilities. It is extremely difficult for wheelchair users, and for people with assistance dogs, low upper body strength or walking aids, to manoeuvre through a door opening against the force exerted by the device and additionally any extra resistance exerted by weather/smoke/acoustic/privacy seals and air pressure differentials. 5.2 Approved Document E: 2010 Resistance to the passage of sound 5.3 Approved Document M: 2013 Access to and use of buildings Approved Document M: 2013 includes an amendment stating that; Where needing to be opened manually, the opening force at the leading edge of the door is not more than 30N from 0o (the door in the closed position) to 30o open, and not more than 22.5N from 30o to 60o of the opening cycle. 5.4 BS 8300:2009 Design of buildings and their approaches to meet the needs of disabled people Code of practice BS 8300 advocates for single or double swing doors, the opening force should not be more then 30N see extract: BS8300:2009+A1:2010, section Controlled door closing devices For most disabled people to have independent access through single or double swing doors, the opening force, when measured at the leading edge of the door, should be not more than 30N from 0o (the door in the closed position) to 30o open, and not more than 22.5N from 30o to 60o of the opening cycle. This means that, in general, only high efficiency door closers mounted on doors with a width greater than 900 mm are likely to meet fire door requirements as well as the opening force limits described above. Controlled door closing devices of a lower power size and with relatively low efficiencies, with a lower power size and/or of a width less than 900mm may only be suitable for non-fire resisting doors. ASDMA Opening forces document Revison C Feb 2016 Page 11

12 BS 8300 advises that The opening force should be checked using a plunger-type force measuring instrument. And Where measurements cannot be taken at the leading edge, they may be taken at a point on the face of the door up to 60mm from the leading edge, a position approximately in line vertically with the spindle of a lever handle or the centre line of a pull handle or push plate, in which case the opening force limits can be increased by approximately 2N. 5.5 BS8300 also recognises that The accuracy of force measuring instruments available on the market varies and there are inherent difficulties in measuring forces on site. It is recognized, therefore, that any measurements are subject to a degree of imprecision which could give rise to variations of between 2N and 3N. Without regular maintenance of all door fittings, the resistances to opening and closing can increase to an extent that the ability of disabled people to pass through the door may be affected. The opening force at the door opening angles described above should therefore be checked at regular intervals. 5.6 BS8300 also recognises the importance of hinges with regards to opening force compliance. BS8300:2009+A1:2010, section Hinges Where it is important to minimize resistance to door opening and closing, hinges with low friction bearings should be selected to carry the appropriate mass of the door. 5.7 BS8300 reiterates the requirements for controlled door closing devices stating; The choice of controlled door closing devices should take account of the efficiency of the closer, as well as the resistances from edge seals, hinge friction, latch resistance and differential air pressure. The effect of using a low efficiency controlled door closing device is to reduce the closing force to a point where, coupled with the other resistances to closing, the door may not latch, or stay closed if unlatched. The use of high efficiency closers can reduce the force required to open the door and increase the proportion of the disabled population who can pass through independently. Where the force required to open a fire0resisting door on a circulation route exceeds the limits (as stated in BS8300 section 6.5.2) an electrically powered hold-open device, either stand alone or integral in the body of the closer, which confirms to the requirements of BS EN 1155 should be installed. These hold open devices will close upon the interruption of the electrical supply. The use of swing-free controlled door closing devices should be limited to applications where doors are located for access to rooms or similar locations and not part of a circulation route. The use of delayed action controlled door closing devices should similarly be avoided in circulation areas The maximum closing force exerted by a controlled self-closing device should be within 0 and 15 of final closure. Controlled door closing devices that do not have this characteristic should be avoided. ASDMA Opening forces document Revison C Feb 2016 Page 12