An outline of the Construction (Design and
Management) Regulations 1994
The Construction (Design and Management) Regulations
1994, abbreviated to the CDM Regulations, came into force on the
31st March 1995.
Safety, Health and Welfare at Work Regulations,
which are also applicable to the Republic of Ireland, are referred
to in the GPDA's 'Healthier Building with Gypsum Products' publication
No. 1.
The CDM Regulations apply to construction projects
and everyone associated with them. The regulations place new duties
on clients, designers and contractors and have created a new duty
holder - the planning supervisor. All these duty holders have
a role to ensure that health and safety is taken into account
and managed effectively throughout all stages of a construction
project - from conception, design and planning through to the
execution of works on site and subsequent maintenance and repair.
Poor management is a prime cause of the unacceptable
accident record of the construction industry.
The most important publication which is available
which provides advice on how to comply with the law is the Code
of Practice which has been approved by the Health and Safety Commission
and which has a special legal status.
All of the 24 individual Regulations are reproduced
in the Code and most of them are provided with guidance on how
to comply with the relevant Regulation.
If duty holders are prosecuted for breach of
health and safety law, and it is proved that they have not followed
the relevant provisions of the Code, a Court will find them at
fault - unless they can show that they have complied with the
law in some other way.
Several other publications are available which provide guidance
on how to comply with the CDM Regulations; these include 'A Guide
to Managing Health and Safety in Construction'. This publication
explains how CDM affects each phase of the construction project
and the importance of teamwork in achieving health and safety
success.
Detailed guidance for those involved in the
design process is given in the publication 'Designing for Health
and Safety in Construction'
The subject of the CDM Regulations and how designers can help
to avoid or reduce health and safety risks to construction and
maintenance workers, at the design stage or a project, will be
discussed in the second seminar.
The leaflet entitled 'CDM Regulations - How
the Regulations Affect You' summarises how CDM affects the duty
holders and provides information on where further guidance can
be obtained.
Other Health and Safety Executive Publications
are available and these include the HSE information sheets Nos
39, 40 and 41 which gives guidance on the duties of the client,
the planning supervisor and the designer, respectively.
The CDM Regulations are needed because the construction industry
has a poor health and safety record.
The industry is bedevilled with unacceptably
high rates of death, injury and ill health associated with all
types of projects ranging from new works right through to subsequent
maintenance, repair, refurbishment and eventual demolition.
In the past, the responsibility for health
and safety matters rested largely with the main contractor. The
CDM Regulations now place new duties on clients, designers and
contractors and, as we said earlier, have created a new duty holder
- the planning supervisor.
For the first time, clear duties are imposed
on everyone in the construction process. This may require many
organisations to rethink their approach to health and safety -
including training and education in the procedures to be taken
to comply with the Regulations.
Five key parties have specific duties - and
these can be firms or individuals ( the information given in the
HSE leaflet 'CDM Regulations - How the Regulations Affect you)
- the client; the designer; the planning supervisor; the principal
contractor; and contractors and the self-employed.
Duty holders should ensure that they understand
what they and others need to do under the CDM Regulations and
discharge their responsibilities accordingly. By working together
through teamwork and collaboration with other duty holders, all
parties can improve health, safety and welfare standards on construction
sites and for subsequent work.
Appendix 6 'Requirements of the CDM regulations
at the main stages of a construction project', as given in the
publication 'A Guide to Managing Health and Safety in Construction',
provides an excellent summary of where the requirements apply
to the duty holders at the different stages of a project.
The CDM regulations apply to most building, civil engineering
and engineering construction work, including:
- New-build construction
- Alteration, maintenance and renovation of
a structure
- Site clearance
- Demolition and dismantling of a structure
- Temporary works
The CDM Regulations will generally apply to
construction work which is notifiable i.e. the construction work
is expected to last more that 30 working days or work of shorter
duration but which is expected to involve more that 500 person
days of construction work.
It's the planning supervisor's responsibility
to ensure that the relevant local Health and Safety Executive
area office is notified of the project. The HSE has to be notified
in writing.
The flow diagram which is give on page 6 of
the HSE publication 'A Guide to Managing Health and Safety in
Construction' helps us to check if a project needs to be notified
to the HSE.
The Regulations also apply to non-notifiable
work which involves five people or more on site at any one time,
and to all demolition or dismantling work - regardless of the
length of time of the number of workers. The exceptions are when
the local authority is responsible for enforcing health and safety
or where demolition work is carried out for a domestic client.
Let's have a look at some examples of when
the CDM regulations do not apply to construction work:-
The CDM Regulations do not apply to construction work when a local
authority is the enforcing authority for health and safety purposes.
This means that the construction work is not notificable and applies
to minor internal construction work in occupied premises. Appendix
3 of the Code of Practice provides details.
CDM will not apply to construction work which
is carried out for a domestic client, so long as their residence
is not used in connection with a business. However, the project
will need to be notified to the HSE. The situation may be different
if a domestic client has entered into an arrangement with a developer.
The regulations do not apply to construction
work if the work will last for 30 days or less and involves 4
or less people on site at any one time.
When the CDM regulations do not apply, all other relevant health
and safety legislation will still apply to employers and the self-employed
carrying out construction work.
If you have any query as to whether the CDM
Regulations apply to any construction work don't hesitate to contact
your nearest HSE office.
From the designer's point of view it's very important to be aware
that the CDM regulations apply to all design work carried out
for construction - no matter how long the site work lasts and
no matter how many workers are involved on site. We'll be discussing
the designer's duties later.
Something which I haven't referred to so far is that the Regulations
have also introduced two very important new documents the 'Health
and Safety Plan' and the Health and Safety File'
The Health and Safety Plan serves two different purposes:-
There is the pre-tender stage health and safety
plan and the planning supervisor has to ensure that this is prepared
to include health and safety information obtained from the client
and designers.
Guidance on what should go in a pre-tender health and safety plan
is given in the HSE Information Sheet No. 42.
For most projects the planning supervisor will
be an organisation e.g. architectural practice. Except for the
smaller projects it is unlikely that the planning supervisor will
be an individual.
There is also the health and safety plan for
the construction phase which the principal contractor is required
to develop before work starts on the site. It is the foundation
on which health and safety management of construction work is
based.
The health and safety plan will need to be added to; it will need
to be reviewed and updated as the project develops; as further
design work is completed; as information for the sub-contractors
starting work becomes available; and to take account of unforeseen
circumstances or as variations to planned circumstances arise,
etc.
Very helpful guidance on what should go in
the health and safety plan for the construction phase is given
in HSE Information Sheet No 43.
The health and safety file is a record of information
which tells those who will be responsible for structure in future
of the risks that have to be managed during maintenance, repair,
renovation or demolition. The planning supervisor has to ensure
that it is prepared as the project progresses. The file is given
to the client by the planning supervisor when the project is complete.
Guidance on preparing the health and safety
file and what the contents could be are given in HSE Information
Sheet No 44.
Finally, in order to help contractors play
their part in the successful management of health and safety during
construction work don't forget that - regardless of whoever is
visiting the site - wearing of safety helmets and protective footwear
should be standard procedures.
HEALTHIER
BUILDING WITH GYPSUM PRODUCTS
GPDA SEMINAR No. TWO
The CDM Regulations and how designers can help
to avoid or reduce health and safety risks in construction - including
when specifying gypsum products and related systems.
Firstly, a few words about 'The Management of Health & Safety
at Work Regulations 1992'
These Regulations already place general duties on employers and
the self-employed to make effective arrangements for managing
health and safety. These regulations also make more explicit the
requirements of the relevant section of the Health and Safety
at Work etc. Act 1974.
Under the management of Health and Safety at
Work Regulations, designers, irrespective of whether they be employers
or self-employed persons, have a duty to assess the risks arising
from their work. However, this assessment doesn't necessarily
consider the effects that the design work may have on the health
and safety of those who subsequently build the structure.
A summary of the Management of Health and Safety
at Work Regulations is given in Appendix 1 of the Approved Code
of Practice L54 which relates to the CDM Regulations.
The CDM Regulations place new duties on designers
to rethink their approach to health and safety and to ensure,
as far as is reasonably practicable, projects are designed to
avoid or reduce health and safety risks while they are being built
and subsequently maintained.
Where risks remain, they have to be stated to
enable reliable performance by a competent contractor.
Designers, of course, have always had to make themselves aware
of the risks associated with certain types of work and to design,
specify and cost accordingly - high risk work such as demolishing
a tall structure or providing temporary supports to an existing
one; building on contaminated land; or where there may be subsidence
risks; removing asbestos.
However, the health and safety risks involved in many other types
of work have been less widely appreciated and consequently the
opportunities to reduce these risks at the design stage have been
lost.
The consequences of a designer not designing
a building which avoids or reduces health and safety risks could
be very serious. Apart from the legal implications, the bad publicity
from HSE investigations could be very damaging.
Designers have often left the responsibility for most health and
safety matters with the main contactor. Although having said that,
the CDM Regulations do not place extra duties on designers or
the management of health and safety on site during construction
- this remains the responsibility of the contractors.
We referred to the pre-tender health and safety
plan in Seminar One. The planning supervisor has to ensure that
the plan is prepared before the tendering process and brings together
the health and safety information obtained from the client and
designers and this helps the clients to appoint a principal contractor.
It's very important that clients, and planning
supervisors who advise them, allow sufficient time for principal
contractors to develop health and safety plans before construction
work starts.
The principal contractor will need to update
the construction phase plan as work progresses and to ensure that,
as far as is reasonably practicable, every contractor complies
with any rules contained in the health and safety plan.
The Approved Code of Practice L54 provides practical
guidance on compliance with the provisions of the CDM Regulations
and other relevant health and safety at work legislation which
is applicable to construction projects.
The publication entitled 'Designing for Health
and Safety in Construction' provides detailed guidance on the
CDM Regulations for designers involved in construction work. Everyone
involved in the design process should familiarise themselves with
the guidance given in this book.
The CDM Regulations, together with the associated
Code of Practice L54, and other publications such as the designers
guide represent a concerted efforts to reduce the unacceptable
high rates of death, injury and ill health which bedevils the
construction industry.
For the first time, clear duties are now imposed
on everyone in the construction process, from the client to sub-contractor
to improve health and safety on site. Health and safety must now
be taken into account from conception of a construction project
right through to completion.
Apparently, those who spend their working lives
on construction sites have a 1 in 300 chance of being killed.
Workers are over fives times more likely to be killed on a construction
site than in a factory.
So why is the designer so important? Research carried out by the
Health and Safety Executive showed that about a third of accidents
on site could be eliminated by designer change, and that a further
third could have been prevented by improved planning before construction
work commenced.
Designers play a key role in a construction projects. They may
be the only people able to make decisions that will eliminate
or reduce foreseeable risks.
By designing to avoid or reduce health and safety risks, designers
are helping to create an environment which assists contractors
in managing the site works - whether it be during the construction
of a new structure or during the subsequent repair, maintenance
and possible demolition.
Unfortunately, the Association of Planning Supervisors,
which is the largest organisation for planning supervisors in
the UK, has found that there is now substantial evidence that
many designers are not undertaking their CDM responsibilities
effectively - particularly in not making clients sufficiently
aware of their duties.
Designers are the key to making clients aware
of their duties under CDM. For example, explaining to the client
the importance of an early appointment of the planning supervisor.
Experience is also showing that designers are
not sufficiently altering their designs to talking account of
health and safety risks. Very often, risk assessments are only
being made after the design is completed.
The Approved Code of Practice L54 refers to the designer's responsibility
as being:
"Designers must design in a way which avoids, reduces, or
controls risks to health and safety as far as is reasonably practicable
so that projects they design can be constructed and maintained
safely. Where risks remain, they have to be stated to the extent
necessary to enable reliable performance by a competent contractor".
Designers should ensure, as far as is reasonably
practicable, that the health and safety of those who are going
to construct, maintain or repair a structure is considered during
the design process. If they don't they make it difficult for a
contractor to devise a safe system of work. Contractors have to
manage the risks on site, but designers can often eliminate or
reduce them in the first place.
The design, and we'll have a look at the definition
of 'design' very shortly, must include adequate information about
any aspect of the structure or materials which might affect the
health and safety of any person at any time.
Designers develop from
initial concepts through to a detailed specification. At each
stage, designers form all disciplines have a contribution to make
in avoiding or reducing health and safety risks.
Designers may need to
work with other professionals such as specialist surveyors and
engineers. Communication between designers and contractors at
an early stage should also be encouraged.
Unfortunately, experience is showing that designers' knowledge
of health and safety is limited. There is a need for more training
to be included in university courses and from more frequent visits
to site to learn about the link between design, construction and
health and safety risks.
Discussions with manufacturers
and suppliers of building products and systems is also recommended.
For example, to discuss problems which certain products may cause
- such as components of excessive weight.
Recommendations could be obtained, for example, on the use of
lightweight metal framed systems and how, in addition to speed
of assembly, they can considerably reduce the injuries associated
with heavy, traditional construction. Metal framed systems that
could be used, for example, as partitions or suspended ceilings.
One of the main advantages
of steel framed buildings is that they provide off-site prefabrication
- and reduce on-site installation injuries.
Advice could be sought on ways of reducing the large amounts of
dust which can be produced on site.
Time doesn't allow us
to consider all of the CDM requirements on the designer but these
are given in Regulation 13 as reproduced in the Approved Code
of Practice L54.
It's very important that
designers make themselves aware of Regulation 13 and comply with
the requirements.
The definitions of 'design'
and 'designer' are given in the Code of Practice:
'Design in relation to any structure includes drawing, design
details; specification and bill of quantities (including specification
of articles or substances) in relation to the structure.
'Designer' means any
person who carries on a trade, business or other undertaking in
connection with which he -
a) prepares a design, or
b) arranges for any person under his control (including, where
he is an employer, any employee of his) to prepare a design,
relating to a structure or part of a structure.
The terms 'design' and 'designer', therefore,
have a very board meaning in the Regulations. Anything which is
designed makes the author a designer. Even a drawing on the back
of an envelope would be classed as a design.
It's very important to be aware that the CDM Regulations apply
to any design work, no matter what size of type of construction
work is, and no matter how long the work lasts and how many workers
are involved on site.
One of the client's main duties is to select and appoint, as soon
as possible, a competent planning supervisor and to appoint a
principal contractor. The planning supervisor has the overall
responsibility for co-ordinating the health and safety aspects
of the design and planning phase.
There are conflicting opinions on whether
the planning supervisor should be a multi-disciplinary team or
an individual. It's argued that individual planning supervisors
cannot be competent to fulfil the variety of duties under CDM.
One of the designer's responsibilities
is to co-operate with the planning supervisor so that health and
safety information can be passed on and incorporated in the pre-tender
stage health and safety plan. The planning supervisor has to ensure
that the pre-tender plan is prepared. This plan is then made available
to contractors who are tendering.
Guidance on the pre-tender stage health
and safety plan is given in HSE information sheet No:42.
Where health and safety risks are not obvious from the design
documents, the designer must provide additional information to
all relevant parties.
As we said earlier, the successful principal contractor is required
to develop the pre-tender plan before work starts on site. Guidance
on what issues could be include in the health and safety plan
for the construction phase is given in the HSE information sheet
No:43.
The planning supervisor must also ensure,
during the construction phase, that a health and safety file is
prepared and that this is given to the client at the end of a
project. This is a record of information which tells all of those
responsible for the structure of risks that have to be managed
during any future design, maintenance or demolition of the structure.
Guidance on the health and safety file is given in the HSE information
sheet No:44.
A summary of the designer's key duties,
as far as they are reasonably practicable, is included in the
HSE leaflet 'CDM Regulations - how the Regulations Affect You'.
Guidance on the duties of the designer is given in the HSE information
sheet No;41.
Alert clients to their duties;
Consider during the development of designs
the hazards and risks which may arise to those constructing and
maintaining the structure;
Design to avoid health and safety risks
so far as is reasonably practicable;
Reduce risks at source if avoidance is
not possible;
Consider measures which will protect all works if neither avoidance
nor reduction to a safety level is possible;
Ensure that the design includes adequate
information on health and safety;
Pass this health and safety information
onto the panning supervisor so that it can be included in the
health and safety plan; and ensure that it is given on drawings
or in specifications etc;
Co-operate with the planning supervisor
and, where necessary, other designers involved in the project.
Let's now briefly discuss the GPDA and how the specification and
use of the member companies' gypsum products and related systems
can help the designer to avoid or reduce health and safety risks
in construction.
The objective of the GPDA is 'to promote,
encourage and develop the use of gypsum products'. On behalf of
the Association's member companies I'd like to remind you, first
of all, of the main types of gypsum products that are available.
Although gypsum is one of the World's
most widely used building material, and is highly admired in its
finished form, its use in the manufacture of an extensive range
of pre-mixed building plasters, plasterboards and glass reinforced
boards is not always recognised.
class="bodyText">Gypsum products provide high standards
of fire protection and can help to prevent loss of life and property.
Gypsum products and systems can also provide
high standards of sound insulation in all types of building.
Thermal laminates are also available which can considerably improve
the thermal insulation of building elements in new and existing
buildings.
Pre-mixed gypsum plasters only require the addition of clean water
to prepare them for use and they are the modern way of plastering
many types of internal backgrounds including brick, block, concrete
and plasterboard.
The use of sand and cement undercoats
has now been largely superseded by gypsum plastering. Defects
can often be experienced with sand and cement undercoats due to
problems such as an incorrect grade of sand being used and/or
insufficient time being allowed for the drying shrinkage before
the gypsum finish is applied.
Gypsum plasters are also much lighter
in weight and from a health and safety point of view this reduces
the physical strain on the plasterer. Long term exposure to cement
dust can also result in chronic chest disorders and cause dermatitis.
The choice of gypsum plaster depends on the required surface hardness
or impact resistance and on the characteristics of the background.
For example, whether the background is of low, medium or high
suction and the type of key which it provides. Gypsum plasters
are also available to satisfy specialist requirements such as
X-Ray protection.
The vast majority of gypsum plastering is undertaken manually
as a two coat hand applied method. One coat hand applied plasters
are also available including one-coat gypsum plaster applied by
a plaster projection machine.
As far as plasterboard is concerned, specifiers
and users are increasingly recognising that plasterboard dry linings
provide several distinct advantages. Since the mid 1980's plasterboard
sales in Western Europe have risen by around 5% per year - which
is well above the average for other building materials.
The wide range of plasterboard types and sizes means that there
is a board for every wall or ceiling installation in all types
of new build or renovation work. All gypsum plasterboards provide
fire protection and sound insulation and other types are available
to provide even higher levels if required.
In addition, there are boards which can provide moisture resistance;
water vapour resistance; greater impact resistance; or even sound
absorption. Plasterboards with decorative white faces or with
raised panel surfaces are also available.
Laminates which incorporate gypsum boards and thermal insulating
backings are used to provide insulated wall linings in new buildings
and to upgrade the thermal insulation of walls and ceilings in
existing buildings.
Thermal laminates can also be used to
provide insulation at the rafter level of pitched roofs.
Laminates which incorporate moisture resistant glass reinforced
gypsum lining can also produce higher standards of thermal insulation
in situations such as exposed floors where the perimeters are
open to the elements.
The boards can be used as a dry lining
by following the manufacturer's recommendations for jointing and
surface treatment.
Alternatively, the boards can be given
a traditional plaster surface by using a finish coat plaster which
is approximately 2mm thick - or a skim coat as it's often referred
to.
Glass reinforced gypsum boards are also
available which can provide high standards of fire protection
at lower costs when compared with other specialist fire protective
boards. The boards also offer a superior finish, higher impact
and moisture resistance.
They can also be used to provide curved
features.
If plasterboards or glass reinforced gypsum boards or laminates
are screw fixed to lightweight metal framing systems, high performance
wall lining can be provided which are easy and economical to install
and which offer high performances.
High performance also applies to metal
formed partitions; walls; and suspended ceilings.
A specifier no longer has to search for and put together different
components and them obtain substantiation for the required performances.
He can now consider selecting from the GPDA member companies'
extensive ranges of tested systems and obtain whatever technical
assistance is necessary to ensure that requirements are satisfied
- including advice on the CDM regulations.
After that brief discussion on some of
the main gypsum products that are available to the specifier,
let's now discuss how the designer will have to take into account
any health and safety risks which may arise in the use of these
products on site.
If you were to ask any construction worker what is one of the
most irritating activities on site, the chances are they would
say "the amount of dust which is produced".
Is dust a hazard? Does it have the potential
to cause harm?
The harmful affects of dust can range from skin irritation right
through to cancer. The degree of risk is dependent upon the type
of dust and amount of exposure. But it's important to remember
that dust can cause injuries and be life threatening. We've already
said that designers must eliminate or reduce risks before the
contractors begin their work.
Gypsum dust is generated mainly from the handling, opening and
mixing of bagged plaster and the cutting and sanding of plasterboards
and glass reinforced gypsum boards.
Fortunately, the effects of exposure to
gypsum dust are relatively minor and gypsum products are not classified
as hazardous under the CHIP Regulations - The Chemicals (Hazard
Information and Packaging for Supply) Regulations.
Gypsum is also not hazardous to health
as defined in the COSHH Regulations. (The Control of Substances
Hazardous to Health Regulations).
Gypsum dust is a nuisance and irritant rather than a serious health
hazard.
However, the HSE Report, 'Dust and Noise
in the Construction Process' says "since long term consequences
(of exposure to gypsum powders) are not yet fully understood,
control of the possible risks should be practised".
The Health and Safety Executive stipulates
Occupational Exposure Limits (OELs) for building materials. These
limits refer to the respirable and inhalable airborne dust particles.
The limits for gypsum products are unlikely to be exceeded except
in poorly ventilated or confined spaces.
Because gypsum dust may irritate the respiratory
system and also skin and eyes, all operations where gypsum dust
may be generated should be kept to a minimum and carried out in
well ventilated areas. If dust cannot be controlled, the wearing
of dust masks and safety goggles is required. To avoid skin contact,
protective gloves, overalls and footwear should be worn.
Although it will be the contractors' responsibility
to ensure that these precautions are carried out on site, there
are several ways in which the designer can further reduce the
production of dust.
Confined spaces, such as basements with inadequate ventilation,
should be identified at the design stage so that suitable precautions
may be included in the health and safety plan. This may require
the provision of dust-extraction equipment or fitting dust bags
to tools, etc.
Plasterboard dry lining can be specified
so as to minimise the depth of chasing in masonry walls for pipes,
conduits and cables. Cutting chases in masonry walls can produce
large amounts of dust which can exceed exposure limits for both
those undertaking the operation and others in the vicinity.
Plasterboard dry linings screw fixed to lightweight, metal frameworks,
which are virtually independent of the background, provide a wider
cavity between the wall lining and the background. This facilitates
the incorporation of services and eliminates the need for chasing.
With some independent lining systems,
services can be installed behind the lining and accessed via a
fire-rated access panel.
Other ways in which the designer can reduce
the production of dust include providing storey heights which
will allow plasterboard to be used as a wall lining without the
need for cutting. This will reduce dust from cutting (and reduce
wastage).
The cutting of chases can also be considerably reduced if lightweight,
plasterboard lined, metal framed partitions and walls are specified
rather than masonry constructions. In addition to the excellent
performances which they can provide, including high levels of
fire resistance and sound insulation, metal stud partition and
walls allow for very easy inclusion of services during construction.
Cut-outs in the webs of the studs can
be used for routing electrical cables and other small services.
These are normally installed after one side of the wall or partition
is boarded. Cables should be protected by a conduit, or other
suitable precautions taken, to prevent abrasion when the cables
pass through the metal frame.
The metal sections of some partition systems
have round or half-round cut-outs which can take rubber grommets
to prevent abrasion of electrical cables.
Metal fixing channel is installed between the studs to support
recessed switch boxes and socket outlets. These may need to be
backed with rock mineral wool to maintain a fire resistance requirement.
In accordance with the requirements for
electrical installations, cables which are concealed within a
wall or partition should be located at least 50mm from the surface
opposite to where the electrical point, accessory or switchgear
is positioned.
If this is not possible, non-metallic sheathed cables should be
installed vertically or horizontally within a 150mm wide zone
from its connection to an electrical point, accessory or switchgear
all of which are positioned on the wall or partition in straight
runs. Alternatively, cables should be installed within 150mm of
the top of the wall or partition or within 150mm of the junction
between two adjacent walls or partitions.
If none of the requirements which we've
looked at can be achieved, the concealed cable must incorporate
a suitable earthed metallic covering or enclosed in earthed conduit,
trunking or ducting in accordance with BS 7671. Alternatively,
mechanical protection should be used sufficient to prevent penetration
of the cable by nails, screws, and other fixings.
The installation of electrical services
should be carried out in accordance with BS 7671:1992 'Requirements
for Electrical Installations'.
Where services such as ducts, fire dampers
and access panels are required to penetrate a metal framed construction,
their positions should be pre-determined so that a framed opening
can be provided. All services, apart from those to be installed
on the surface of the lining, should be independently supported
from the structure. The duct or other similar service should be
suitably fire stopped.
By designing service openings through
which a larger number of services can pass, the number of individual
service penetrations will be reduced. Service openings in drywall
construction need to be fire-stopped by materials which have been
tested to the European standard EN 1366-3.
In most situations, the services will
be installed by contractors other than the dry lining contractor.
So it's important that all relevant contractors are advised as
to where and how their service penetrations should be made and
maintained.
Services which penetrate building elements need careful consideration
to ensure that any required fire resistance is not impaired and
that the services do not act as a means of spreading fire. Optimum
sound insulation is also achieved only by airtight construction.
All service penetrations need to be adequately
fire-stopped.
It's very important to use only those
services and their installations which have been shown by fire
test to be able to maintain the fire resistance of a construction.
Let's continue with the discussion on
how the designer will have to take into account any health and
safety risks which may arise in the use of gypsum products on
site.
So that a gypsum board can be safely carried,
on edge, by two men, the size and weight of the board need careful
consideration - particularly if handling is in confined or very
exposed situations. Risks to health and safety are also greater
when working at height.
Size and weight of the board are even more of a consideration
if only one man is handling the board.
The designer will also need to consider then possible use of mechanical
handling methods not only to reduce the risk of manual handling
injuries but also to speed up construction. Discussion with the
planning supervisor can ensure that suitable provision is included
in the health and safety plan.
The use of lightweight metal framed walls
and partition will also reduce the manual handling problems associated
with heavy building blocks. It's often wrongly assumed that it's
only heavy, traditional material that can provide high standards
of performance such as fire resistance and sound insulation.
Just for your information, as a result
of research sponsored by the GPDA, the maximum bag weight of gypsum
plaster is now 25kg rather than 40kg. The smaller bag is now helping
to reduce manual handling strain - particularly when repetitive
manual lifting is unavoidable.
We've already briefly discussed thermal
laminates but I'd like to now give a little more information on
them and also on how the designer needs to consider any potential
risks which may be associated with their use.
As we've already said, thermal laminates
combine the benefits of a plasterboard dry lining with backings
of thermally efficient insulation materials. These backing materials
include, phenolic foam, extruded polystyrene, expanded polystyrene
of high and low density, and mineral wool.
The laminates provide a dry internal lining
with all the advantages of room located insulation. This is so
important in intermittently headed rooms in order to reduce surface
condensation and to provide comfort conditions for the occupants.
Thermal laminates are mainly used for insulating wall in new buildings
and to considerably improve the thermal insulation of existing
masonry external walls. Thermal laminations can also be used to
insulate at the rafter level of pitched roofs; and to contribute
to the thermal insulation of new and existing timber flat roofs
in conjunction with mineral wool insulation.
However, the designer needs to consider any potential risks which
may be associated with the backing materials of some of the laminates.
One potential risk is that related to the insulating plastic backings
(of expanded polystyrene and extruded polystyrene) which, although
they incorporate a flame retardant additive, they are combustible
if exposed to a sustained source of ignition and will generate
dense smoke. The flammability hazard increases when it is in dust
form. Precautions may need to be included, therefore, in the health
and safety plan and the health and safety file if, for example,
blow torches or other forms of naked flame are used during construction
or eventual maintenance.
Dust from phenolic foam is classified
as a weak explosive. Therefore, suitable dust extraction and collection
systems should be used to avoid possible explosions when phenolic
foam backed laminates are cut using mechanical saws.
Suitable fire extinguishing media such
as CO2, water, or foam should also be available on site.
Electrical cables give off heat when in use. Where cables are
covered by thermal insulation they may overheat and increase the
risk of short circuit or fire. Cables should be fixed, therefore,
so they can dissipate heat. This is one of the advantages of using
metal framed wall lining systems which provide a cavity between
the lining and the masonry background.
Where cables are covered by thermal insulation,
advice needs to be obtained on what specific precautions are necessary.
For example, by reference to the IEE Wiring Regulations or the
Electricians Handbook. PVC sheathing to cables can have a reduced
life expectancy if in direct contact with expanded or extruded
polystyrene insulants. Fix PVC sheathed cables so that they are
not in direct contact with the polystyrene backings of thermal
laminates. Alternatively, run them in conduit.
Irrespective of what type of insulation is on the back of the
thermal laminate, a suitable earthed metallic covering should
be specified if the cable is within 50mm of the surface of the
plasterboard lining. Alternatively, mechanical protection should
be provided to avoid penetration by nails and screws, etc.
The backing material of thermal laminates
should never be cut to accommodate services.
That concludes this talk on how designers can help to avoid or
reduce health and safety risks in construction - particularly
when specifying gypsum products and related systems.
Obviously a discussion of all of the risks is not possible but,
on behalf of the GPDA, I have drawn to your attention some of
the main health and safety risks which may arise during construction
and eventual maintenance.
