Demountable Partition systems For Offices by UK Partition Manufacturer Apton

The Building Regulations

Principal parts in relation to relocatable partitions

Part B Fire Safety

Part E Resistance to passage of sound

Part K Protection from falling, collision and impact

Part M Access and facilities for disabled persons

Part N Glazing – safety in relation to impact

Relocatable partitions - Relevant British and European standards

BS 476 Fire test on building materials and structures

BS 952 Glass for glazing

BS1186 Timber for workmanship in joinery

BS1230 Gypsum plasterboard

BS4787 Internal/external doorsets, leaves and frames

BS5234 Partitions (strength and stability)

BS6180 Barriers in/about buildings – Code of practice

BS6206 Impact performance requirements for safety glass in buildings

BS6262 Code of practice for glazing in buildings

BS7974 Application of Fire Safety Engineering Principles to the Design of Buildings (Code of practice)

BS8212 Code of practice for dry lining and partitioning

BS EN 1364 Fire tests for non-load bearing elements

BS EN ISO 140 Acoustics – measurement of sound insulation

Building Regulations and Standards

BS EN ISO 717 Acoustics – rating of sound insulation

ETAG 003 Internal partition kits

ETAG 003 Internal partition kits for use as non-loadbearing walls

Essential requirements

• Fire
• Health and hygiene
• Safety in use
• Protection against noise
• Energy and economy
• Durability and serviceability

BS 5234 Strength and stability

BS5234, part 2: 1992 Internal non-load bearing partitions

Specification for performance requirements for strength and stability. Includes methods of test; details the various test requirements, performance levels and test method

Acoustic control in regard to glazed partitions is primarily a factor of

i) Glass thickness and type

ii) Single or Double Glazing

iii) Air gap between glass faces

These factors are obviously controlled by the construction of the partition, and the following table shows the type of dB reduction that may be expected in various constructions.

The table above gives the results as Rw(dB) or rated weighting.

The Rw(dB) figure is a method of comparing one system to another on a level playing field. As sound is a product of both frequency and pressure, the test procedure for internal building constructions is based on 16 frequencies, from 100Hz to 4000Hz. Sound will penetrate materials and constructions to a greater or lesser degree dependant on the frequency. In order to prevent manipulation of test result curves, by isolating and selecting the most favourable sectors, a control curve   BS 5281, is placed over the test and an average or Rw(dB) is calculated.

This table should be read in conjunction with table S2 (below) and the Leakage Point Diagram (see section on Acoustics), which give an indication of sound levels and main sound leakage points, in a typical installation. The tables however do not give the whole picture, as there are circumstances where If the particular frequencies of the noise pollution are known and relatively constant, then a glass and/or construction can be selected which is ideal for those conditions, as differing frequencies have differing penetration effects.

For instance, in the accepted speech range of 400Hz to 2500Hz a 12.8mm PVB laminate can give as good results as a 19mm monolithic glass, with considerable savings in initial costs, as well as transport and installation cost savings. Another example is for external windows, where 4mm single glazing gives a better result for road traffic frequencies (RTRA) than some double glazed units.

Table S2

As can be seen in the previous table, a relatively small change in dB rating gives a large change in acoustic performance. This is because the dB scale is logarithmic not linear. The important thing to remember, is that the higher the figure the more difficult it becomes to gain additional sound resistance.

It is important when seeking to obtain the best acoustic installation, to consider at the space planning stage the layout and position of sound sensitive areas, as efforts made at this time can  be significantly more productive than attempting to ‘block’ the sound at a later point: ‘prevention is better than cure’, and in this situation certainly more cost effective. Without doubt the best acoustic solutions are achieved by bringing the partition supplier into the project as early as possible.

Fire resistance in glazed partitions can take the form of being

Integrity Only (E)

Integrity and Radiation reducing (EW)

Integrity and Full Insulation(EI)

The letters E, EW, and EI are the proposed new European codes for the glass types.

Table F1 gives an indication of the radiated heat level against time which may be expected from the various glass types.

Radiation controlled glasses are those which reduce the measured level of radiated heat to less than 15kW/m²at 1 metre distance.  Using normal panel sizes, this is the radiation level at which it is considered to be impossible for the spontaneous ignition of building materials, or for a heat zone to be generated barring the safe passage of people.

The radiation reducing glasses are nominally 7-11mm single layer laminates or gel filled. The full insulating glasses are multi-laminates or gel filled.12-55mm in thickness. The use of radiation reducing glasses will undoubtedly increase as more European standards bodies set standards for radiation control without the requirement for full Insulation.

The selection of the type of glass is primarily controlled by the fire safety officer, for the project with reference to Building Regulations. These will cover escape routes, distances, active safety systems within the building etc.

The prime usage of insulating or radiation reducing glasses is around stairwells and escape route meeting points, where radiated heat will be a major factor in safe escape. The industry is aware that some of the regulations regarding FR screens can be improved upon by using Fire Engineered solutions, specific to the building, which may result in lower insurance premiums. The Loss Prevention Council in their Code of Practice make mention of this approach in their guide for the fire protection of buildings.

A very important factor concerning the thickness of glass suitable for any application is whether the glass has 4 edges or 2 edge support. As an example a 1250x2500 6mm 4 edge supported panel under a load of 1500N/m² has a deflection of 17.8mm. A similar size 12mm 2 edge supported panel under a load of 800N/m² has a deflection of 43.5mm.

Even at this deflection the glass would be well within its allowable stress rating, but may be outside allowable deflection limits depending on position and building usage. This is especially true for atrium situations if the glass is used as a full height barrier. For general office use using 4 edge support, i.e. a standard stud and track partition, a 1200mm wide panel can be safely glazed up to 3000mm in 6mm toughened or 6.4 laminated glass. For a frameless glazed (2 edge supported) system the following tables give an indication of recommended sizes.

Table G1

2 Edge supported glass, Standard Office use. Non- protecting drop. Standard Medium duty loadings.

Where a drop or atrium is being protected, or where a building has public access, such as a school or government building, it may be necessary to use the heavy duty loadings as shown in Table 3 below. Under those circumstances, the next thickness of glass up (i.e. 2mm to 15mm) will be required for the recommended maximum glass height.

An Indication of Deflection under constant load and panel width, but with change of glass thickness is given in Table 2 below.

Table G2

2 Edge supported glass

Maximum permitted deflection can be generally assumed to be 25mm @ 1100mm above floor level. Free standing barriers are subject to different stresses, and deflection should be constrained to 20mm.

A rule of thumb is that moving up to the next standard glass thickness, halves the deflection under the same load conditions. These figures are themselves subject to variation.  If for instance a run of 3 panels was set into a solid opening, then the end two panels would have 3 edge support, the glass being slotted into an abutment track.

This would considerable stiffen the run (assuming the middle panel was dry or silicon jointed to the outer panels) OR Clamping at the bottom edge of the glass, between 100x100x12mm angles can halve the deflection, allowing the use of a thinner glass for any specific height, i.e. 12mm can be used in place of 15mm. This is mostly employed for free standing glass screens where the angles can be set beneath raised floors or under the screed, but can also be used at atrium bases where it can be made a feature.

Depending on building usage, screen design and construction can be adjusted.

The sizes of the glass used, must, as previously mentioned, also take into account the building usage, and the following table gives the British Standards for loads against building usage.

Table G3

In addition for atria and barriers, glass must:

i) Conform to BS6206, and BS6180

ii) Resist the usage design loads

iii) Be within deflection limits

iv) Glass must not break under specified impact test

v) Have impact performance to BS6262 and Building Regs Doc

vi) Glass for atriums must have a minimum of 15mm edge cover at the head or glass thickness x1.5. This may also be necessary at the head to incorporate slab deflection, where a deeper head channel can be fitted. Slab movement can be positive and negative.

Where atria are concerned care must be taken if there are additional requirements other than barrier protection, or If the loading calculations indicate a larger thickness of glass than is desired or can be handled. In these cases it may be necessary to incorporate a separate handrail barrier independently secured to the slab at 800-1100mm ht sufficiently strong enough to take the required loadings.

As an alternative support posts can be secured to the slab and bolted to the glass panels preferably at 1100mm ht. There are prescribed hole sizes and clamping plates for this which are covered by the various British Standards This would obviously require the glass to be pre-drilled and is really only suitable for toughened glass not laminated. This may cause problems if there is a requirement for the containment of any glass in the event of breakage.

Safety films can be applied to toughened glass to contain any breakage, but in the case of bolted through systems, the film will need to be applied prior to installation. Obviously barriers and atriums are not necessarily all glass and the loadings applicable vary according to their position on the screen.

Important point to remember when specifying atrium glazing with 2 edge support

1. Take loadings to be heavy duty unless contractor/architect states otherwise

2. The smaller the aspect ratio of the panels (height divided by width) the better. This applies to point loads only and does not affect line loads.

3. Large panels require specialist installation, and have cost and safety implications.

4. If the system can be switched to framed, almost certainly a cost saving can be made.

From these various tables it can be taken that as a general rule, for 2 edge supported glass barriers, 10mm Toughened glass is not suitable for use in any atrium situations, unless the following conditions are met:

1. There is an independently mounted handrail or dwarf wall/partition protecting the glass at dado rail ht(1100mm approx) sufficiently strong to withstand the site loads.

2. The glass ht is 2000mm or less, and the line loads do not exceed 740N/lm

3. Glass can be clamped at 1100mm ht by post mounted, approved single point glazing clamps.