home » technical
guide » the
case for doorsets »
The doorset is a fully
finished, engineered element comprising of frame, pre-hung door
leaf (with any vision panels) and essential ironmongery, all
matched and pre-assembled in the factory. It is delivered to
site as a package for reassembly
and simple installation.
In contrast, traditional door assemblies consist of the
same elements but usually from various different sources, with
final assembly and finishing carried out on site - frequently
involving different trades.
Leaderflush Shapland
doorsets are designed as complete, engineered units to meet
specific performance requirements and manufactured to exacting
standards from established components under factory conditions
ensuring:
- minimised intervention on site
- consistent fitness for purpose
- straightforward replication of certified
test conditions within the building
Appendix B of Approved Document B
"Any test evidence used to substantiate the fire resistance
rating of a door should be carefully checked to ensure that it
adequately demonstrates compliance and is applicable to the
adequately complete installed assembly. Small differences in
detail (such as glazing apertures, intumescent strips, door
frames and ironmongery etc) may significantly affect the
rating".
The importance of doorsets is acknowledged by BS 8214: 1990
'Code of practice for fire door assemblies with nonmetallic
leaves':
"It is strongly recommended that pre-hung, pre-finished, fire
doors (i.e. doorsets) are specified whenever possible as this
reduces the amount of site work necessary and allows normal
factory quality control procedures to be applied to the
finishing operations."
BS 8214 calls for testing of complete fire door assemblies or
doorsets, fully representative of all aspects of how they will
be used on site. For door assemblies, this is far more
problematic with potential for combinations of mismatched,
uncertified
components and poor site practices. In addition
to fire resistance, other performance criteria can be achieved
and maintained more easily with doorsets, including:
- smoke containment
- sound reduction
- durability
This is due to the factory finishing, matching and fitting of
the various components which work together to meet performance
levels. Other guidance documents recognise this, such as HTM 58
Internal Doorsets:
"The high performance standards
required of door leaves, frames and ironmongery in health
buildings can best be met when these components are accurately
fitted and matched in a factory and delivered to site as a
complete unit (i.e. doorset)."
Independent research has
addressed commonly held misconceptions about the capital costs
of doorsets by using an objective comparison of realistic,
current market prices compared with those of site-assembled
unitary components. This research used single stage tenders for
three real projects from reputable, national door contractors.
With all building types considered, savings in capital costs
were shown
for doorsets over the average for contractors
using site assembled unitary components clearly showing that:
Doorsets can save up to half the initial capital
cost of traditional door assemblies.
The
doorset concept is a well-established example of the
prefabrication and off-site product techniques advocated today
under the 'Modern Methods of Construction' banner. Current
initiatives, based on 'Constructing Excellence' principles, call
for greater efficiency and savings in all areas of the building
industry, not just construction costs. To satisfy these
requirements, research has analysed differences in the
procurement process and consequential time implications for
architect, consultant quantity surveyor and main contractor's
estimator, between doorsets and unitary component assemblies.
This analysis showed that doorsets substantially
simplified the procurement process and offered overall
time/cost savings of 50%.
Over 60 different
components make up a typical storey height door assembly. It is
generally accepted within the building industry that:
Substantial
installation time and cost savings are achieved on site with
doorsets over unitary component assemblies.
"There is an overwhelming case for the use of performance
doorsets in place of site assemblies of unitary door components
in today's building industry."
|
