Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a method of adding floors to
existing building structures, and is particularly, but not
exclusively, concerned with adding such floors to structures
of historical or architectural value.
In high density urban areas, land is very expensive and
it is often desirable to provide building structures with as
many floors as possible to satisfy a social need for office
space, living space and the like. However in many such
high density urban areas there are frequently many older
buildings with a relatively small number of floors and it is
very desirable to be able to add floors or to build above
such buildings. These buildings are often valuable sources
of heritage and of considerable historical and architectural
value. Thus the obvious solution of demolishing such
buildings to make way for new high rise buildings with many
floors is impractical and attempts to do so may result in
protests and lawsuits from environmental and historical
lobby groups. When these older buildings were constructed,
some of them were designed to take additional floors,
however this was usually intended to be no more than five
floors and usually only two or three floors. This does not
satisfy the requirement of providing a substantial amount of
additional office or living space.
One proposed solution to this problem is to incorporate
the original building structure within the new building
structure by building an external support or cage around the
original structure and to support a platform truss on new
external columns so that the platform truss supports a
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subsequent construction skeleton to provide the new floors
above the truss. However, using external columns has a
number of important disadvantages. For example, such a new
structure may obscure the original facade, and it also
requires land to be available all around the existing
structure. Such adjacent land is very rarely available in
high density urban areas. To acquire such land and provide
foundations all around the original structure, would result
in considerable expense as well as engineering problems. An
important disadvantage is that the appearance of the
original structure is obscured and this is not desirable.
An object of the present invention is to obviate and
mitigate the disadvantages associated with previous methods
and to provide an improved method of adding extra floors to
an existing building.
Accordingly, in one aspect of the present invention
there is provided a method of adding a number of floors to
an existing structure. This method comprises providing
additional foundations at least within the perimeter of the
original building structure, providing internal columns
supported on the new foundations and bringing these columns
through the roof of the original structure. A platform
truss is then supported on these new columns and a plurality
of floors can be added above said platform and supported
thereon using conventional building construction techniques.
In a preferred method of adding new floors to an
existing building structure, all of columns are within the
perimeter of the original building and are brought through
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the roof of the original structure. The platforM truss is
supported on all of these internal columns. The platform
can then support a conventional construction skeleton which
may be made of concrete for providing additional floors on
top of the existing floors.
An alternative method, where some adjacent land is
available, internal columns can be provided through the
original structure and a new foundation provided adjacent
the original structure. External columns provided on the
adjacent foundations are the same height as the internal
columns. A platform truss is provided over the internal
columns through the original structure and new exteral
columns and a conventional construction skeleton can be
mounted on the platform truss so that the floors overlie in
part the original structure and the new structure.
These methods have the advantage that the original
facade and appearance of the building is maintained and that
the amount of land required to facilitate such method is
minimal and indeed in the preferred embodiment, all
construction can be done within the original perimeter of
the original structure.
Other aspects of the invention are the structures when
constructed by such methods.
These and other aspects of the invention will become
apparent from the following description when taken in
combination with the accompanying drawings in which: -
Fig. 1 is a perspective and exploded view of parts of abuilding to be constructed in accordance with the preferred
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method of construction to provide additional floors above an
existing building structure;
Fig. 2 is a diagrammatic and perspective view showing
an alternative method of construction where the original
building has some available land adjacent one side;
Fig. 3 is a diagrammatic perspective view in which a
new intermediate floor can be located inside an old building
in accordance with an alternative method according to the
invention; and
Fig. 4 is a diagrammatic view showing how the building
shown in Fig. 3 can be further modified to include the
platform for providing additional floors on top of the old
building.
Reference is firstly made to Fig. 1 of the drawing
which shows a perspective, partly broken away and exploded
view of the parts required to construct a building structure
in accordance with a preferred method of construction. An
existing building structure, generally indicated by
reference numeral 10, is provided with an additional
foundation indicated by reference number 12, which
intersects the original foundation and provides a base for
new internal columns 14 which rise through the interior of
the building above the roof 16. A large platform truss 18,
which is preferably made of steel, is supported by the
columns 14 and this platform 18 supports the conventional
steel skeleton 20 for providing the additional floors above
the existing building structure 10.
It will be appreciated that in Fig. 1 some excavation
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is required around the base of the original building
structure and a basement wall, indicated by reference
numeral 22, requires to have access holes made for
construction and to provide new foundation adjacent to the
S original foundation. As will be seen, the new foundation 12
intersects with the original foundation wall 24, shown in
dotted outline, and underpining and cause of intersection of
the new and old foundations. It will also be seen that
between the walls of the original structure, a spread
footing pads 26 are provided to provde a floating foundation
in the trench underneath the existing foundation and
basement floor. In Fig. 1, eight internal steel and
concrete columns 14 are shown and it will be appreciated
that the dimensions and material of these columns will be
designed in accordance with conventional construction
methods by persons skilled in the art and form no part of
this invention.
Additionally, the steel platform truss 18 is
dimensioned and designed according to conventional
construction techniques in accordance with known structural
requirements and the exact dimensions do not form part of
this invention. However, it will be appreciated that in
order for the platform to support a conventional steel
skeleton 20 designed to add a significant number of floors,
it should be of a sufficient depth to transmit the load of
the skeleton 20 and any additional building structure
through the platform 18 and the internal columns 14 to the
foundations. A suitable thickness for this truss would be
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10 to 16 feet high and this would depend of course on the
length and breadth of the truss as well as the weight of the
structure above it. Similarly, the steel skeleton will be
designed in accordance with conventional techniqes and this
does not form part of the present disclosure.
An alternative method of adding floors to an existing
structure is shown in Fig. 2. This method is suitable when
there is a piece of land available immediately adjacent to
the existing structure. In this situation the existing
building structure 30 has additional foundations and
internal columns, generally indicated by reference number
32, extending right through the interior of the building and
through the roof, in the same manner as shown in Fig. 1.
The additional structure also has internal columns and these
are brought up to the same height as the columns 34
extending through the existing structure. A platform 36 is
positioned on the new and original building structures
supported by columns 32 and 34. A steel skeleton, not
shown, could be added in a similar manner to that shown in
Fig. 1 but would spread across the whole of the platform
above the existing building structure and the addition.
Reference is now made to Figs. 3 and 4 which shows how
the method can be used to provide a new intermediate floor
38 inside an existing building 40. This is particularly
advantageous where the interior of the building requires to
be removed or an intermediate floor provided if the building
interior is very high, for example in a church or factory or
! the like. The advantage of this technique is that the
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facade and exterioe of the building remain unaltered.
Foundations and internal columns are provided as previously
described and the new intermediate floor platform truss 38
is provided, supported on the internal columns. The columns
can be brought through the truss or additional columns
provided on top of the intermediate truss and brought
through the roof 44 of the building. A platform truss 46
can be supported on these columns in the same manner as
previously described with references to Figs. l and 2, and
provides the base for a construction skeleton for providing
additional floors as previously described.
Without departing from the scope of the invention, it
will be appreciated that there are various modifications
which can be made to the method as herebefore described.
For example, although eight internal support columns are
shown in Fig. 1, the number of columns and size would depend
on the exact structural requirements and on the type of
building required to be modified and also on the size of the
building. Similarly, the exact size and material of the
platform truss would depend on the relative dimensions of
the existing structure and the number of floors required to
be added above the existing structure. Obviously the
greater the number of floors, the larger the columns and the
truss will be. Although the materials for the columns and
truss have been described as steel, it will apparent to
those skilled in the art that a truss could be made of
cor,crete or other suitable material in accordance with the
necessary structural requirements. Furthermore, the
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platform could be made of steel or concrete beams instead of
a truss or could be made using a continuous concrete pour.
The internal and external columns could also be incorporated
in load bearing walls or load bearing walls per se could be
used to act as the columns.
The preferred method does not require significant
adjacent land and is thus very attractive for high density
urban areas where it is desired to add office or living
space above and existing structure without modifying the
existing facade. In situations where adjacent land does
become available, then the method illustrated with reference
to Fig. 2 could be used and of course the addition could be
placed on either side of the building, but most preferably
on the side with the least architectural significance which
is least likely to modify the appearance of the existing
structure.
The technique as shown in Figs. 3 and 4 is very
advantageous where a complete renovation is required inside
an existing structure but the original facade must be
maintained. This technique can also be very advantageously
used if it is desired to add an intermediate floor to an
atrium building, for example a church or a factory. It is
possible to further modify the structure to add floors above
it by incorporating a platform truss through which columns
pass to new foundation within the original structure as has
been previously described.
Advantages of this method are that the existing
exterior of the building is unchanged and the historical and
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architectural significance is retained. A minumum of
adjacent land is required, and an existing structure can
easily be modified to take a significant number of floors to
provide sufficient office and accomodation space as required
in high density urban areas. This affords an architect with
the opportunity of blending the new part of the structure
with the existing structure or the other buildings in the
vicinity.
Without departing form the scope of the invention it
will be appreciated that alternative construction methods
may be used. For example, in the case of a factory the
ground floor could be modified to use as the foundation.
Additional support platform trusses could be provided above
the existing structure and spaced apart by support columns
if the new structure requires a great number of floors.
