Civil Engineering Reference
In-Depth Information
and cannot be discussed here; nevertheless specifications of
clear-span large-volume spaces allowing the space to be con-
figured as desired without interference from wall or columns,
tend to be the minimum required. In these design briefs, the
structure must not become an undue encumbrance to delivery
of a client's requirements.
It is therefore more reasonable in this context to outline some
of the normal considerations for the typical private market or
housing association type residential apartment buildings which
tend to be developed on the basis of 'volume build'. Speed of
construction and repetition will therefore be an important con-
sideration to the developer who will often be the contractor
(or construction manager) as well, and therefore driving con-
struction from the perspective of development value for max-
imum return. The quicker the development can be delivered
to market the better and therefore speed and regularity of con-
struction will become more important than the pure economic
equation of the type of construction itself.
Design loading requirements will typically be at the lower
end of any building loads. In addition to any particular in-
ishes load, the imposed load requirements will generally be
1.5 kN/m² although in larger space areas and in apartment
design a further 0.5 kN/m² can be required for lightweight mov-
able or demountable screening or partitioning. Congregational
areas such as terraces and shared lobbies may require greater
load to be allowed for.
An important requirement within any residential use is the
provision of natural daylight. Structure within external eleva-
tions should therefore be kept unobtrusive and downstand
beams avoided or kept to a minimum. Upstands may some-
times be more acceptable where, for example, a perimeter
beam may be required. Perimeter support structure (walls and
columns) within or close to party walls may need to be checked
for fire resistance since these are locations where horizontal
fire spread must be considered.
Floor heights within apartments (excluding duplex double-
height space) need to be proportional to reflect the depth
of the spaces, and to optimise natural light into the rooms.
Nevertheless the spaces should not become so cavernous as
not to be cosy. The normal bounds are therefore deemed to be
floor to ceiling heights of a minimum of 2350 mm to an ideal
of 2700 mm to 2900 mm. Clearly decisions may be driven by
maximising the number of floors in a given height for eco-
nomic reasons or restricted by planning constraints but the
more that internal height is compromised the more this may
adversely reflect the market value of the residential units.
Structure that might involve internal downstands should be
avoided in general and most certainly in large space areas such as
living and dining rooms. Any downstands which are unavoidable
should be strategically placed since they cause light shadowing
and interference with light paths and are generally perceived as
an inconvenience in residential structures. The most preferable
location for any downstands is above defined division wall lines
where a nominal bulkhead might be utilised if necessary.
The form of slab construction needs to be given very care-
ful consideration particularly in the UK where compliance with
Building Regulations Part E (The Building Regulations, 2010)
for acoustic separation places stringent requirements on the
floor not to allow transfer of noise between occupancies. These
Regulations define tight acoustic (noise) resistance criteria that
the floor build-up shall meet in the form of 'robust details' (those
deemed as compliant if adopted). This usually requires the use
of a thick dense concrete or the use of 'floating floors' specific-
ally designed for acoustic separation. Alternatively, those con-
struction details deemed not to align with robust details would
require
in situ
testing but this brings about potential risk very
late in a construction programme which is best avoided.
Proprietary forms of residential construction may also be con-
sidered for developments up to four or five storeys. These may
take the form of both metal (cold-rolled) or timber framing and
are lightweight compared to traditional house construction mate-
rials of masonry or concrete framing. Such systems become suit-
able for mixed-use developments where the residential element
may be placed above other uses with large span requirements.
These system-build forms of construction also offer greater sus-
tainability credentials using materials with less embedded energy,
may be fabricated off-site and can be quicker to construct.
8.7 Schools
Educational buildings may have many uses, from primary,
middle or secondary schools to colleges and universities.
The discussion in this section focuses mainly on multi-storey
buildings developed for secondary school use although many
aspects of the design considerations will apply to all.
Teaching methods and curricular content constantly change
from year to year. New technologies have had a considerable
effect on the space and the environment needs for educa-
tional buildings and advancement in this area continues apace.
The structure designed for these buildings therefore needs to
ensure that it would not unnecessarily hinder the ability for
the building to adapt and create flexible space. The structure
should therefore ideally be framed rather than rely upon any
internal load-bearing elements other than those that would
remain unchanged, for example, core walls.
Typically teaching spaces will not be heavily serviced within
floors or ceilings. Indeed it may be common for there to be
no finishes requirements for floors or ceilings (other than dec-
orative); power to the spaces is typically provided within wall
trunking, heating being in perimeter lines, lighting from ceiling
fixed or hung 'rafts', and IT provision via wireless means or
wall trunking. Floors can typically therefore be simply power
floated to receive a vinyl-type finish.
Additionally, the internal environment and particularly the
teaching spaces should benefit from maximisation of daylight
(with appropriate limitation of glare). This would lead to the
structure avoiding use of downstands particularly at the perim-
eter where if an edge beam is needed an upstand arrangement
may be more suitable.
