Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF INSULATING METAL DECK ROOF STRUCTURES
This application is a continuation-in-part of copending related application
08/645,993, filed 14 May 1996.
TECHNICAL FIELD
This invention relates to the construction of an in~ ted metal roof
structure for use in commercial and industrial buildings.
BACKGROUND
Metal roof structures typically comprise a framework of a plurality of
10 structural beams, such as trusses, bar joists, and purlins. The roofs are commonly
in~ ted. Various methods of providing an in~ ted roof structure have been used.
A first prior art roof structure comprises a plurality of rafter beams
extending across the building in one direction and a plurality of purlins parallel to each
other mounted on top of the rafters extending in a direction normal to the rafters. The
15 roof structure utilizes long sheets of flexible insulation material which are positioned in the
area between purlins. Because the flexible insulation can be placed in the area between
purlins, a relatively thick layer of insulation can be used in this type of insulated roof
structure, providing a roof structure with relatively good insulation properties, or R-
values. The insulation material can be laid along the length of the purlins or across the
20 purlins in a direction normal to the purlins. Various methods of supporting the insulation
material have been used. Mounting straps or wire mesh which are attached to or draped
over the purlins forming a lattice have been used. This is referred to as banding. A sheet,
typically made of vinyl and acting as a vapor barrier, is then rolled onto the lattice, and
insulation material is placed between adjacent purlins and over the sheet.
Some systems dispense with the lattice and use the sheet itself to support
- the insulation material. The support sheet is draped from the adjacent purlins and the
insulation material is placed on top of the support sheet. A carriage has been used to aid in
the dispensing of the support sheet. The carriage is positioned on top of the purlins and
travels the length of the purlins during the roof construction. A roll of the support sheet
30 material is mounted on the carriage and the support sheet is payed out from the rol} and
placed on top of the purlins. As the carriage travels the length of the purlins, the support
sheet is draped across the purlins. The use of the carriage generally greatly speeds
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in.ctAll~tion time, and generally greatly decreases the installed cost of the insulation
material.
Metal panels are then fastened to the purlins over the insulation material.
Because the metal panels come in long sheets and the roofs often have two sloped5 sections, it is customary to construct the roof along the length of the structure from one
end to the other. The workers stand on the previously laid section of roof to construct the
next section. Since the metal panels are exposed to the outdoor weather environment, the
metal panels are fastened together such that a waterproof seal exists, thus providing for a
waterproof roof structure. The metal panels are made from relatively expensive materials,
10 such as galvanized steel, galvanized ~ mimlm, or copper. The metal panels commonly
have interlocking structures and pre-applied sealant. These waterproof sealing methods
are relatively expensive due to the cost of the panels and the labor associated with
assembling them.
A second prior art roof structure comprises a pluraiity of parallel trusses or
15 bar joists which are mounted on a supporting girder. The roof structure includes relatively
inexpensive metal deck sheets which are fastened to the trusses. Generally, the metal deck
sheets are not fastened together such that they provide for a waterproof seal, and they are
made from relatively inexpensive metals. Rigid insulation board, such as styrene foam or
high density glass wool, is then applied on top of the metal deck sheets. Under certain
20 conditions, such as in colder clim~tes, the use of additional layers of rigid insulation board
in this insulated roof structure has a decreasing cost effectiveness as the thickness of the
rigid insulation board increases. It is therefore difficult many times to cost-effectively
achieve relatively high incnl~ting properties with this type of insulated roof structure. A
waterproof membrane, such as a flexible rubber membrane, or a built up roofing system
25 (BUR) is applied over the rigid insulation board. If a leak is developed in the membrane,
- the rigid insulation board saturates with water and the inclll~ting qualities of the roof
structure are decreased.
Although the above mentioned roof structures are adequate, it often is
desirable to have a relatively low cost roof structure having relatively high inclll~ting
30 properties, i.e., a higher R-value. In addition, it would be desirable to have a method of
building a roof structure which is cost effective and efficient to build, which provides for a
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roof structure having relatively high in.c~ ting characteristics, and which provides
protection from water damage for the inc~ tinE material within the roof structure.
DISCLOSURE OF INVENTION
There has now been invented an improved method of building a roof
5 structure which is cost effective and eff1cient to build, and allows for relatively high
- insulation values. The roof is constructed by in~t~lling flexible insulation material between
trusses, applying metal deck panels to the trusses, and applying a temporary waterproofing
sealant to the metal deck. Subsequently, a permanent waterproofing membrane is applied
on top of the metal deck. This method allows the flexible insulation material to be
10 protected from water damage during the construction of the roof structure prior to the
application of a permanent waterproofing membrane. The permanently waterproofed roof
structure has relatively high in.cl~l~ting characteristics.
The present invention comprises a method for providing a roof structure
having a plurality of trusses spaced apart from one another in a parallel arrangement. A
15 support sheet is payed out so that the support sheet depends from the top portions of
j~cf~nt trusses. The support sheet is preferably payed out from a carriage which moves
along the length of the trusses as the roof structure is being built. Flexible insulation
material is applied above the support sheet so that the flexible insulation material is
supported by the support sheet. Metal deck sheets are fastened to the top portion of the
20 trusses in an overlapping manner, thereby forming a metal deck having seams. A
temporary waterproofing sealant is applied to the metal deck to protect the flexible
insulation material from water damage prior to the application of a permanent waterproof
membrane being applied, thereby creating a partially completed roof structure. The
temporary waterproofing sealant can be applied between the metal deck sheets at the
25 regions where they overlap, or can be applied over the seams of the metal deck. Rigid o
- insulation board and a waterproofing membrane are subsequently applied onto the metal
deck, thereby forming a completed permanently sealed roof structure.
BRIEF DESCRIPTION OF DRAWINGS
Fig. I is a sçhem~tic sectional view of a prior art roof structure in which
30 flexible insulation is installed between purlins.
Fig. 2 is a schematic sectional view of another prior art roof structure in
which rigid insulation is installed above trusses.
.
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Fig. 3 is a schem~tic side elevational view of a carriage for paying out
insulation and a support sheet according to the present invention.
Fig. 4 is an enlarged schematic sectional view illustrating the temporary
sealing of two adjacent metal deck sheets.
Fig. S is a s~h.~m~tic sectional view of a completed roof structure inct~lled
according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
There is illustrated in Fig. 1 a prior art roof structure, generally indicated at
10. The roof structure incll~des a plurality of parallel rafters 12 extending across the
10 building in one direction and a plurality of purlins 14 which are parallel to each other
mounted on top of the rafters extçn-linP in a direction normal to the rafters. A support
sheet 16 is draped across ~djAç.ont purlins and flexible insulation material 18 is laid on top
of the support sheet. Metal panels 20 are then fastened to the purlins 14 above the flexible
insulation material so that the edges of the support sheet are sandwiched between the
15 metal panels and the purlin, thereby supporting the support sheet and the flexible insulation
material. Since the metal panels are exposed to the outdoor weather environrnent, the
metal panels are fastened together such that a waterproof seal exists, thus providing for a
waterproof roof structure. For example, the metal panels commonly have interlocking
structures having pre-applied sealant in the interlocking areas. The metal panels are made
20 from relatively expensive materials, such as galvanized steel, galvanized ~Illminllm, or
copper.
Fig. 2 illustrates a di~ prior art roof structure, indicated generally at
3 0. The roof structure includes a plurality of parallel bar joists or trusses 31 which are
mounted on supporting girders (not shown). A metal deck sheet 32 is f~.~tçned to the
25 trusses. Rigid insulation board 34 is placed on top of the metal deck sheets. A waterproof
- membrane 36 is then applied on top of the rigid insulation board, thereby forrning a
waterproof roof structure.
There is illustrated in Fig. 3 a partially completed roof structure, indicated
generally at 40, being installed in accordance with the present invention. The roof
30 structure is supported by girders (not shown). The trusses 31 are spaced apart and
arranged parallel to each other. The spacing ofthe trusses is typically 4 feet (1.46 m) on
centers. As shown in Fig. 5, the trusses include a top portion 42 and a vertical portion 44.
. , , ~ .. . . ..
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Roof structures may also be constructed using bar joists or other similar structures. The
use of the term "trusses" in this specification and claims inclndes not only traditional
trusses, but also bar joists and other sirnilar structural members.
Broadly stated, the partially completed roof structure 40is constructed by
5 use of a carriage 46 which rides on the top portion of the trusses and travels along the
length of the trusses in a dov~l~sLIealll direction, represented by an arrow 48. As the
carriage is moved. a support sheet 50 is payed out from a roll 52. The support sheet is
draped on top of adjacent trusses so that the support sheet depends from the top portion
of the trusses. The support sheet supports a layer of flexible insulation material 54 which
10 is placed on top of the support sheet between the adjacent trusses. The flexible in~ tilm
material is payed out from a roll 56.
The carriage 46 can be any length up to the width of the roof itself.
Preferably, the carriage is comprised of a plurality of carriage sections which can be joined
together so that they span the entire width of the sloped section of the roof. The carriage
15 is then propelled across the trusses by pulling means, such as a winch (not shown), in the
downstream direction 48so that all the carriage sections move in unison.
Since the support sheet is draped across the top portion of adjacent trusses,
the total width of the support sheet is wider than the distance between the trusses.
Therefore, adjacent support sheet rolls are not co-linear and must be slightly staggered.
20 Typically, a carriage section covers two truss spans, i.e., about 10 feet (3.7 m) in length.
Preferably, each carriage section has both a leading roll S2 and a trailing roll 61 of
insulation support sheet, one roll for each of two fldj~cçnt truss spans. The edge of the
support sheet from the trailing roll 61 will be draped on top of the edge of the support
sheet from the leading roll 52 as the carriage moves in the downstream direction. Multiple
25 identical carriage sections, each having a leading and trailing roll, can therefore be joined
- together, with every roll being staggered from an adjacçnt roll.
The carriage can be any suitable apparatus that moves along the top of the
trusses and dispenses the support sheet. As seen from Fig. 3, the carriage 46in~ludes
safety handrails 62 and a walking deck 64 for the worker to stand on while operating or
30 moving the carriage. Preferably, the carriage has hourglass-shaped rollers 66 riding on the
top portion 42 of the trusses 31 for ease of movement and to m~int~in the carriage in
aliFnmçnt with the trusses. The carriage also inçl~1des a framework 68 for mounting the
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rolls 52 and 61. Although two support sheet rolls are shown in Fig. 3, one is the leading
roll 52 shown in the background, and the other is the trailing roll 61 shown in the
foreground. Mounted on the framework are turning bars 70 which extend laterally across
the support sheet and are positioned slightly above the top portions 42 of the trusses 31 so
5 as to direct the support sheet to a generally horizontal position.
The space between the vertical portions 44 of a~j~cent trusses 31 defines an
insulation cavity 72, as seen from Fig. 5. The insulation cavity has a generally rect~n~ r
cross-sectional shape. It is advantageous to fill out the insulation cavity uniformly with the
flexible insulation material without leaving relatively large gaps, thereby ma~rimi7ing the
10 in~ ting qualities of the roof structure. The purpose of the support sheet 50 is to support
the flexible insulation material in the ins~ tinn cavity, but the support sheet can also be
used as a vapor barrier and for aesthetic purposes. A pleated support sheet which reduces
the width of the rolls 52 and 61 can be used. The pleated support sheet unfolds as it is
payed out in the insulation cavity. The support sheet can also be perforated so as allow
15 any water inside the insulation cavity to escape, thus helping to prevent a loss in the
inc~llating quality of the flexible insulation material. The support sheet can be of any
suitable material for the stated purposes, such as vinyl or foil faced paper.
Attached to the carriage is a plate 74 which extends from the carriage 46 in
an upstream direction opposite the do~Jlsl-~a-ll direction 48. Instead of being mounted on
20 the carriage, the roll 56 of flexible insulation material 54 can be rested on the plate. The
plate supports the payed out support sheet so that the support sheet does not drape
downwardly, thereby pulling the longit~ldin~l edges of the support sheet off of the top
portion 42 of the trusses. Generally, the plate is located in a gap 75 which exists between
the partially completed roof structure 40 and the carriage 46. The plate hinders wind from
25 blowing vertically through the gap 75 which could disturb the flexible insulation material
- 54 and the support sheet 50. If built with sufficient strength, the plate can be used for fall
protection for the workers to prevent them from falling offthe leading edge of the
previously completed section of roof. As used in this specification and claims, the term
"fall protection" means that the plate will withstand a live load of 25 lbs/ft2 (1200 N/m2).
30 This should be adequate to support a worker inadvertently stepping on the plate. The
plate, however, can be constructed in any suitable manner. The plate can be ~tt~h~d to
the carriage by any suitable means, such as by a plurality of hooks 76 which extend
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vertically from the plate. The hooks are simply hung on the carriage thereby supporting
one end of the plate. The other end of the plate is supported by rollers 78 which ride along
the top portion of the trusses.
After the flexible insulation material has been placed on the support sheet,
S long sheets of hard roofing material, such as metal deck sheets 58, are then ~tt~ched to the
top portion of the trusses over the support sheet and insulation. The plurality of metal
deck sheets form a metal deck 59. The att~hment of the metal deck sheets presses down
on the edges of the support sheet which are sandwiched between the top portions 42 of the
trusses and the metal deck sheets, so that the support sheet supports the insulation
10 between the trusses.
The metal deck sheets 58 typically have longitudin~lly extending
corrugations to provide for structural strength. Preferably, the metal deck sheets are made
of a relatively inexpensive material not having weather treatment applied to the surface
areas. The metal deck sheets 58 of the present invention are fastened to the top portion of
15 the trusses 31 in an overlapping manner thereby creating a seam 60, as shown more clearly
in the enlarged view of Fig. 4. The metal deck sheets can be fastened to the trusses in any
suitable manner, such as by threaded fasteners. The metal deck sheets come in long
sheets, typically 30 to 35 feet (10.9 to 12.8 m), and the roof would generally have a single
sloped section. A section of the roof structure is constructed first along the width of the
20 sloped section, and then the roof is constructed down the length of the structure from one
end to the other. The workers stand on the previously attached first section of the roof
structure to assemble the next section of roof. The carriage travels along the length of the
trusses and is moved by the workers as each new section of roof is assembled.
As stated before, Fig. 3 illustrates a partially completed roof structure 40.
25 Typically, the invention is carried out by having a team of deck insulation installers, using
the carriage system as described above, construct the partially completed roof structure
40. Afterwards, a team of roofers will apply rigid insulation board 82 and a waterproof
membrane 84 over the roof structure 40 to form a complete permanent waterproof roof
~ structure, indicated generally at 86 in Fig. 5. Since the lapse of time between the
30 construction of the partially completed roof structure 40 and the completed roof structure
86 can be as long as several weeks, the partially completed roof structure 40 should be
protected from moderate weather conditions, such as rain, snow, wind, and direct sllnlight
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Particularly, of greatest concern is protecting the flexible insulation material from
moisture. Since the partially completed roof structure 40 will eventually be covered from
the weather elements by a permanent waterproofing system, the cost of the temporary
protection should be held to a minimllm, and be yet able to with~t~ntl the harmful outdoor
5 environment. The method of the present invention so}ves this problem by applying a
temporary waterproofing sealant to the relatively inexpensive metal deck 59 subsequent to
the construction of the partially completed roof structure 40.
During construction of the partially completed roof structure 40, a first
metal deck sheet 58 is positioned over the payed out flexible insulation material 54 and the
10 support sheet 50, and is fastened to the top portion 42 of the trusses 31. As shown in Fig.
4, a first layer of temporary waterproofing sealant 88 is applied along a longitu(lin~l edge
portion 90 of the first metal deck sheet 58. The sealant can be any suitable sealant which
provides for a temporary sealing, such as a bead of asphalt-based sealant applied by a
caulking apparatus, or an adhesive strip of mastic. It is desirable that the sealant remain
15 relatively viscous when exposed to the elevated temperatures that can be experienced on a
metal deck roof on a sunny summer day, so that the sealant will not flow out of sealing
contact under such conditions. Preferably, therefore, the sealant has a melting point above
about 165~F. More preferably, the sealant is an asphalt that has been oxidized to have a
melting point between about 165~F and about 200~F, and, most preferably, between about
20 165~F and about 185~F. Such an asphalt would preferably have an ASTM D5 penetration
at 77~F ranging between about 15 dmm and about 60 dmm, and, more preferably, between
about 18 dmm and about 30 dmm.
The edge portion 90 is located on the downstream side of the first metal
deck panel. A second metal deck sheet 92, having a longitll~in~l edge portion 94 located
25 on the up~lealll side of the second metal deck sheet, is positioned on top of the first metal
- deck sheet so that the edge portions 90 and 94 of the first and second metal deck sheets 58
and 92, respectively, overlap. Therefore, the first layer of temporary waterproofing sealant
88 will provide for a temporary waterproof seal between the first and second metal deck
sheets 58 and 90. This ovellapping and sealing procedure is repeated after every new
30 metal deck sheet is fastened down. The ends of adjac~nt metal deck sheets are also
overlapped and applied with a sealant which provides for a temporary seal.
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The use of the term "temporary sealant" in this specification refers to any
suitable seal which provides for a waterproof seal that is intended to be merely a
temporary waterproofing system and not a permanent waterproofing system for the roof
structure 40. A temporary waterproofing system is one that would be expected to keep
5 out most of the water from rain, for example, but would not be expected to be a
permanent waterproofing system for a long duration of time, such as several months. Such
a temporary waterproofing system may not be expected to be waterproof for a heavy rain
or snowstorm.
Optionally, a second layer 96 of temporary waterproofing sealant may be
10 applied at the seam 60, which is located at the upstream edge 95 of the second metal deck
sheet 92. Preferably, the second layer of temporary waterproofing sealant 96 is applied by
spraying an adhesive on top of the seam 60. Of course, either the first layer 88 or second
layer 96 of temporary sealant can be applied as the sole temporary sealant for the roof
structure 40, or they can be applied in combination.
In situations in which large holes or openings must be made in the roof
structure 40 to accommodate, for example pipes or heating, ventilation, and air
conditioning systems, the temporary waterproofing system may include sealing the edges
of the opening temporarily to protect the flexible insulation material underneath the metal
deck. Preferably, an enclosure panel or cover (not shown) is used to temporarily seal the
20 exposed sides of the insulation cavity 72. The enclosure panel can simply be a formed
piece of waterproof material which is formed to follow the contour of the exposed roof
structure 86. Preferably, the enclosure panel has a sealing strip, such as a bead of asphalt-
based sealant or a double sided strip of mastic, applied to the edges of the enclosure which
contact the roof. While the enclosure panel does not prevent water from flowing through
25 the large opening into the building structure below, the enclosure panel does prevent or
- inhibit water from entering the insulation cavity and d~m~ging the flexible insulation
material.
Typically a team of roofers will install the rigid insulation board 82 and the
waterproof membrane 84. The rigid insulation board 82 can be any suitable rigid
30 insulation board, such as high density glass wool (about 10 lbs/ft3, or about 160 kg/m3),
rockwool, or styrene foam, and is typically about 1 to about 2 inches (2.5 to about 10 cm)
thick. The rigid insulation board particularly incul~tes the region of the roof structure
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above the truss, since there is no flexible inc~ tiQn material present. The waterproof
membrane can be made of any suitable material, for example, built up roof (BUR),ethylene propylene diamine monomer (EPDM), polyvinyl chloride (PVC), and modified
bitumen, such as asphalt modified with styrene-butadiene-styrene (SBS) or atactic-
5 polypropylene (APP). The application of waterproof membrane provides for a relativelypermanent waterproof roof structure 86.
If the waterproof ~ lllbl ane develops a leak, the rigid insulation board
typically will saturate with water, thus decreasing the in.clll~ting qualities ofthe rigid
insulation board. However, the water leakage is likely not to transmit through the metal
10 deck sheets having the temporary sealant, and thus is likely not to damage the flexible
in~ ting material 54. Therefore, since most of the in~ ting properties of the structure
of the present invention are accomplished by the flexible insulation material, it is likely that
the inc~ ting properties of the roof structure 86 of the present invention will not degrade
as much as the prior art roof structure 30 shown in Fig. 2 upon failure of the waterproof
1 5 membrane.
In addition, it should be noted that the method of the present invention
provides a relatively low cost, relatively high in~ tinsg value roof structure. In particular,
the method of the present invention allows the use of relatively thick layers of insulation to
be applied in a relatively low installed cost manner, such as by a carriage, while at the same
20 time making use of relatively low cost metal deck sheets.
It will be evident from the foregoing that various modifications can be made
to this invention. Such, however, are considered as being within the scope of the
invention.
INDUSTRIAL APPLICABILITY
The invention can be useful in the construction of roof structures for
- commercial buildings.
