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ASDMA Opening forces document Revison C Feb 2016

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)


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


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

1.1 0 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

1.2 30 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


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 Door 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


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.

3.1.1 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

Fig 1. Swipe/wipe mode

3.1.2 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

Fig 2. Compression mode

3.1.3 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.

Door

Frame Seal

Frame

Door

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.

Fig 4. Meeting stile Compression mode

3.2 Door width

Door 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.

Door

Seal

Door

Door Door

Seal Astragal


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 3m3 /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


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

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

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

Door

Frame

Seal

Threshold fitted to floor and or floor finish

Door

Frame

DropSeal

Threshold fitted to floor and or floor finish


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. 0.884m

The equation is as follows: - (N(c) x m = Nm. e.g. 20 x 0.884 = 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.


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. Door

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 6.5.2 – 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.


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 6.5.3 – 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.

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