Note: Descriptions are shown in the official language in which they were submitted.
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Method for assembling a weather-protecting roof truss and a weather-
protecting roof truss bundle
The present invention relates to a method as set forth in the preamble of
claim 1 for the
installation of a weather-protective roof truss, and to a weather-protective
roof truss
package as set forth in the preamble of claim 4.
When building new detached houses and row houses, one major problem is how to
provide weather protection for the structures in a sufficiently early stage.
When the house
is constructed from prefabricated elements in a conventional manner, the
erection of wall
elements tikes about half a day and, thus, there won't be enough time during
the rest of
the day for the installation of a roof for weather protection as this may take
even several
days. This may lead to water damage, and thereby to mold problems which have
been
quite common in recent times. In addition, the installation of roof trusses
according to
current building practice is demanding in terms of occupational safety as it
requires a fair
amount of climbing up and down the roof. The installation work is also quite a
slow
process.
The invention described in this patent application relates to a solution
comprehensively
more efficient than the current practice and prior known technology for the
installation of
roof trusses, roof sheathing and gable elements.
Making use of the invention enables, remarkably more rapidly and efficiently
than
before, the installation of a weather protection in conjunction with the
construction
of permanent roof structures for buildings (such as for example all small
houses or
single-family houses: a detached house, a row house, a leisure time house, and
the
like), which at the same time improves substantially the safety of roofing
jobs, pre-
empts water damage occurrences during construction, and allows for roofing
jobs
also in varying climate conditions. After the installation of a solution
according to
the present invention, the construction jobs can be continued as usual, for
example
by the installation of roof battens and coverings.
It is an objective of the present invention to provide an improved method for
the
installation of a weather-protective roof truss. In order to attain this
objective, a
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method according to the invention is characterized in that the method
comprises
using a prefabricated roof truss package in which the individual trusses are
disposed
side by side for a bundle and previously provided with a weather protection
present
in a pleated condition on top of the truss bundle; unfolding the bundle at
construction site in such a way that the adjacent trusses become locked at a
certain
distance from each other by means of brace members included in the trusses and
at
the same time the weather protection unfolds to cover the trusses and the
intervening space, and finally fastening the individual trusses by outer edges
thereof
to the upper runners. On the other hand, a roof truss package according to the
invention is characterized in that the roof truss package is provided at a
manufacturing plant with a weather protection which is attached to the
trusses, that
the roof truss package has its trusses arranged for a bundle in which the
weather
protection is in a pleated condition, and that the trusses are provided with
brace
members capable of locking the adjacent trusses at a certain distance from
each
other as the bundle is unfolded. In the context of this application, weather
protection is a term used generally in reference to any type of structure or
material
affording protection against the weather and also functioning at the same time
as
roof sheathing and/or condensation sheathing for a roof structure to be
subsequently completed. The material for the trusses is preferably wood, but
the
invention is not limited solely to timber-based trusses.
Making use of the invention enables, remarkably more rapidly and efficiently
than before,
the installation of a weather protection along with the construction of
permanent roof
structures for buildings (such as for example all small houses or single-
family houses: a
detached house, a row house, a leisure time house, and the like), which at the
same time
improves substantially the safety of roofing jobs, pre-empts water damage
occurrences
during construction, and allows for roofing jobs also in varying climate
conditions. After
the installation of a solution according to the present invention, the
construction projects
can be continued as usual, for example by the installation of roof battens and
coverings.
The solution according to the invention allows for the manufacture and rapid
installation of a prefabricated weather-protective robust roof truss. In
comparison
with the conventional installation of roof trusses, the solution according to
the
invention provides a considerable time saving, even up to about 90% faster
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installation, in the installation of a weather-protective roof, and an
improvement in
occupational safety with lesser demand for climbing. The installation of roof
structures in a weather-protective manner as set forth in the invention can be
carried out even in just roughly 1-2 hours. The mold problems caused in the
structures by moistures during construction will be substantially mitigated.
The
quality of roof building in conventional construction work is dependent on the
builder's skills while, when using the solution of the invention, the
workmanship
remains at high standard and consistent regardless of a person doing the work.
The invention cuts back substantially the total completion time of a building
as it reduces
the roof building time and allows for an earlier commencement of interior
jobs. In
addition, the invention provides savings in materials and transportations and
overall costs.
The invention set forth in the patent application offers numerous advantages
over prior
known technology, a few of which will be discussed briefly as follows.
Utilization of commercially available standard components
The invention as presented in the patent application, "a solution for the
installation
of a roof truss", comprises "a weather protection bundle" which in turn
comprises
roof trusses, a roof sheathing, and gable elements as an assembly that can be
produced industrially, in controlled conditions, and in a material efficient
manner.
The working of "a weather protection bundle" is made possible by innovative,
if
desired recyclable components and solutions which enable an operation
according
to the invention by using commercially available components as trusses, a roof
sheathing and gable elements. Therefore, the question is about a comprehensive
invention making use of the entire industry, which differs from all prior
known
techniques in the sense that the weather protection during construction time
is
achieved without supplementary structures (e.g. a tent around the building or
other
structures necessary for establishing weather protection and not a permanent
part
of the house under construction), thereby incurring extra costs.
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The fact that the weather protection problem has not yet been resolved in the
industry can be considered to stem from prior known solutions being liable to
increase labor and material costs. This practical fact demonstrates strongly
the
innovative quality of the invention presented herein.
Reduction of water damaae occurrences durinci construction
A major risk in construction are mold damage occurrences. Mold and water
damage
occurrences constitute a significant problem in terms of national economy.
Most of
the mold damage occurrences stem from exposure to moisture during construction
work. In practice, the water damage occurrences in exterior structures develop
most frequently in conditions wherein the structures (such as walls) are
exposed to
moisture before other permanent structures (such as the roof) have been put in
place.
Therefore, in conditions with the air containing moisture and/or the weather
conditions otherwise fluctuating for example in various seasons, the
construction
time is without specific measures usually restricted to seasons that enable
installation projects to be conducted with a minimum risk of damaging the
structures during construction. In practice, this entails that for example
roofing jobs
are limited to a minimum, among other things, when it is raining or snowing,
because the structures do not withstand rains to significant extent. As
roofing jobs
occupy a central role in the house building project, other construction work
of the
building will be delayed respectively as long as the roofing jobs cannot be
carried
out and the structures thereby protected from elements (in other words be
"weather-protected"). Accordingly, for example in Finland and in numerous
other
countries where conditions are not rainless and warm throughout the year, the
effective and safe construction seasons for buildings is restricted to just a
few
months of the year.
The climate-imposed limitations on a construction season lead to major
challenges
both for individual builders and developers and more extensively for
construction
industry. Due to these limitations, construction is not only slow but the
effects
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extend also, among others, to the productivity of construction sector and the
jobs
available for construction workers.
At the request of Ministry of the Environment and by working with
universities, the
5 construction industry has for a long time endeavored to create a standard
that
would define measures during construction for preventing these water damage
occurrences in construction time (a so-called "weather protection standard").
An
objective of the weather protection standard is to ensure for the structures
such a
protection during construction that water damage cases and resulting major
financial and health-related setbacks shall not take place. Even despite years
of
efforts by the authorities, a solution to the weather protection problem has
not been
found prior to coming up with the present invention.
The currently employed methods are based on protecting a building with a
sheathing separate from the building, such as for example by constructing "a
tent"
upon the building for the duration of construction. Such a solution is loose
from the
actual structures and it must be constructed separately for protecting the
building.
The construction of a separate protective sheathing postpones the commencement
of construction works as well as increases construction costs substantially.
In the
event of using "a tent", the construction of a separate protective sheathing
is
followed by the actual roof building work with conventional methods on a
conventional schedule. On the other hand, with the invention according to this
patent application, the weather protection can be established without separate
procedures (and without putting on separate tarps) along with the ongoing
installation of roof trusses. Since the installation of roof trusses can be
conducted
with the present invention on average even up to 90% faster than with
traditional
methods, the structures will be provided with weather protection considerably
sooner and, therefore, the risk of water damage occurrences is remarkably
mitigated. With the invention presented in the patent application, weather
protection during construction is accomplished considerably faster and more
cost
effectively than with the prior known competing method (a separate "tent"/tarp
system). When utilizing the present invention, the installation of roof
trusses can be
followed by proceeding faster to the finishing installation of battens and
roof surface
materials, whereby the final completed roof structure and hence a protection
for the
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building in its final condition is also achieved faster. The present invention
also
allows for a certification of the construction method in a manner that enables
the
rapid installation of weather protection to be documented for a client who has
ordered the house. This is another aspect that promotes construction quality
as well
as customer safety.
Because the invention presented in the patent application enables roof trusses
and
weather protection to be installed considerably faster than what has been
known
before, there will be significant advantages gained over prior known
technology.
Improvement of occupational safety
As already pointed out above, the present invention has an objective of
providing an
improved method for the installation of roof structures, a weather-protective
roof
truss, as well as providing an innovative roof truss package the utilization
of which
enables the foregoing objectives to be attained. In addition to the fact that
the
invention according to this patent application reduces remarkably the hazard
of
water damage incidents during construction, expedites the installation of a
roof, as
well as the building construction work to continue in various weather
conditions, the
invention according to this patent application can also be used for
significantly
improving the safety of building construction work.
When compared to other industries, it is the construction sector where most
occupational accidents take place in Finland. The annual number of
occupational
accidents in construction industry is about 17000-19000 - the occupational
accident
incidence rate in construction industry is about twice as high as in the next
most
accident-prone sector.
Within construction industry, more frequently than in others occupational
accidents
occur in building construction sector with the risk of an occupational
accident in the
latter being 2-4 times higher compared to other industries. The most typical
workplace accidents in construction industry include falls, slips, jumps and
trips.
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Construction industry is also where most fatal workplace accidents occur. The
most
common cause of fatal workplace accidents in construction industry is a fall
from
height.
In building construction industry, the risk of workplace accident is
particularly
pronounced in roof work. Roof working jobs involve particularly a risk of
falling from
height, which is why the fall protections for roof work sites are specifically
regulated
in the Council of State Ordinance on the safety of construction work. Hence,
measures mitigating the hazardousness of roof jobs are profoundly meaningful
in
construction industry.
Making use of the invention according to this patent application renders it
possible
to reduce significantly the time spent for roof jobs, to reduce the amount of
high-
risk roof work, to expedite and promote safety measures needed for the
finishing
touches of a roof, and thereby to improve comprehensively the safety of roof
construction jobs.
First of all, the traditional installation of roof trusses is highly time-
consuming work
the fulfillment of which is, as presented above, dependent on weather
conditions.
On the other hand, both the installation of roof trusses with a method of this
patent
application and the use of a roof truss package according to this patent
application
render the installation of roof trusses significantly faster with respect to
traditional
methods: With the invention set forth in the present application, the
installation of
roof trusses can be successfully performed as much as about 90% faster than
with
techniques known prior to the invention. Just the significant reduction in the
installation time of roof structures alone brings about respectively a
significant
reduction in the probability of occupational accident occurrences.
Secondly, with traditional solutions, the roof truss is installed from outside
the
building manually regardless of whether or not the above-discussed "tent" is
used
as a weather protection. When using traditional techniques, the installation
of roof
trusses from outside nevertheless requires very hazardous climbing movements
on
top of the roof trusses undergoing installation. In addition, the installation
of roof
trusses from outside necessitates the installation and use of hoists and
scaffolds,
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which is time consuming, expensive and likewise involves risks from the
standpoint
of occupational safety. Instead, the method according to the invention for the
installation of roof truss can be carried out from inside the building
manually after
the roof truss package has been placed at one of the gables of the house or at
some other starting point. Consequently, making use of the invention according
to
this patent application renders it possible to reduce significantly the risks
of
workplace accidents in the installation process of roof trusses since the
installation,
as opposed to traditional techniques, does not require hazardous climbing
movements on top of the roof trusses.
Thirdly, after the completion of a roof sheathing, the roof construction work
progresses conventionally to roof finishing work such as, among others, the
installation of battens and roof surface materials. This work necessitates
setting up
safety rails and other safety equipment, which in its part increases
occupational
safety risks. When using the invention according to this patent application,
the roof
truss bundles can be pre-fitted at the factory with safety rails needed for
the
installation of a roofing (such as for example battens and metal roofing, clay
tile
roofing or other roofing). This both expedites the installation of roofing and
improves remarkably occupational safety as the safety features need not be
installed on site for the roof finishing work.
The roof work reducing, roof work nature changing, as well as use-of-safety
features facilitating effect of the present invention, and the occupational
safety
improving substantially as a result thereof, constitutes in and of itself a
highly
significant innovation and a remarkable improvement with respect to the prior
art
and its longstanding problems.
The invention will now be described with reference to the accompanying
drawings,
in which:
Fig. 1 shows one roof truss package for use in a method of the
invention at a
commencement stage of installation,
fig. 2 shows
the roof truss package of fig. 1 in a partially installed condition,
=
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figs. 3a, 3b show one detail in a roof truss of the invention, and
fig. 4 shows a roof truss of the invention in an isometric view.
In the process of installing a roof truss, it is a roof truss package in the
form of a bundle
which is lifted with a hoist onto the roof and placed at one gable of the
house or at some
other desired starting point and braced to an upright position from an
outermost truss 3.
In the exemplary case shown in fig. 1, a bundle 1 has been hoisted to the
upper part of a
building onto top runners 6 of the building's opposite walls 7 at one gable of
the building.
The top runners are mounted to rest on load-bearing upright posts of the
walls.
Fig. 1 shows also one exemplary embodiment of a roof gable element, which
comprises an
eaves section 12 and a gable wall section 13, said gable element having been
preferably
pre-fitted at the factory to the attachment with the roof truss at both ends
thereof.
Prefabrication in this context refers to manufacturing conducted in a factory
building or the
like sheltered space irrespective of whether the production is automated or
mechanized or
manually conducted production. The eaves section 12 comprises fascia boards 18
and
soffit boards 19. The gable wall section 13 includes studwork 14, which is
fastened to an
outermost truss 3 of the bundle 1 and to which is fastened a wind protection
slab 15. On
top of the wind protection slab is mounted studwork 16 with exterior wall
panels 17
fastened thereto.
After this, the bundle is unfolded by moving it with the assistance of an
installation
cradle (not shown) along the roof, the bundle releasing one truss at a time.
Fig. 2
shows a bundle in a partially unfolded condition. The unfolding can be
conducted
e.g. by means of a winch or a hoist. Preferably, the installation is conducted
from
inside the building by using a remote controller for manipulating the winches
which
operate the installation cradle. The trusses are fitted with lower brace
member 4
and upper brace members 5 capable of locking the trusses at a predetermined
distance from each other to provide a previously supported structure, wherein
individual trusses, except for the first truss, need not be separately
supported on
the building frame structures. The number of each of the brace members 4 and 5
is
at least two per truss.
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Figs. 3a, 3b show one preferred embodiment of the lower brace members 4 more
closely
in schematic views of principle. Fig. 3a depicts a starting condition, and
fig, 3b shows a
condition in which a truss 3' next to the gable truss 3 has been removed from
the gable
5 truss to a distance defined by the brace member 4. In the presented
exemplary
embodiment, the brace member 4 consists of a two-component support, having
first and
second support arms 4a, 4b which are pivotally connected at one end thereof to
the
trusses 3 and 3', respectively, and at the other end thereof to each other
with an
articulated joint 4c capable of locking the support arms to each other while
defining a
10 distance between the trusses 3, 3'. The upper brace members 5 are
designed similarly as
a two-component unit. The number of brace members 4 and 5 is typically 4-6 in
each
inter-truss space. The brace members are preferably accompanied by clamping
elements
which keep the truss bundle intact and, upon undamping, release the brace
members of
the next inter-truss space to unfold as the truss bundle is advanced. The
material for the
brace members can be e.g. metal, plastics or wood or various combinations
thereof.
After unfolding, the trusses are attached by outer edges thereof with
fastening means to
upper runners 6 for preventing the wind from jerking the truss bundle off from
top of the
upper runners. The fastening means may comprise e.g. an angle bar or the like.
The roof
truss bundle is previously equipped at the factory with a weather protection
2, which is in
a pleated condition on top of the bundle 1 and in attachment with the trusses,
such that,
as the bundle is being unfolded, the weather protection straightens out to
cover the space
between adjacent trusses. Once the bundle has been completely unfolded, the
roof is
immediately in a weather protected condition. The weather protection can have
two or
more layers, thereby facilitating the use of new materials more advanced in
terms of their
absorption/breathability or insulating properties.
Alternatively, a roof truss of the invention can be previously unfolded even
on the platform
of a transport vehicle, on retractable rails or on the ground, and then
hoisted onto the
roof, whereby all that is necessary to do on the roof is to fasten the trusses
to the upper
runners.
Fig. 4 shows in a schematic isometric view a roof truss in a partially
unfolded condition.
The weather protection 2 is in this example fastened to individual trusses by
means of
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ventilation ribs 11. The weather protection is provided separately on both
slopes of the
roof for enabling the pleating thereof for transport. On top of the
ventilation ribs 11 at the
roof apex will be provided a separate weather protection strip (not shown),
which enables
effective ventilation in a completed roof structure and protects a ventilation
gap of the
weather protection 2 developing at the apex. The strip can be previously
mounted on top
of the ventilation ribs 11 of the weather protection 2 on one of the slopes to
facilitate its
installation while the roof truss is in a completely unfolded condition.
