Bulit-up roof (BUR) or modified roof assembly system

Roofing system is presented comprising a built-up roof(BUR) assembly or modified roof membrane assembly (MRM) which is adhered to gypsum, concrete or composite sheets or panels which have been loose-laid over a roof substrate. This allows the BUR or MRM assemblies to conduct heat to or receive heat from the thermal mass of the loose laid mass-weighted sheets immediately below the BUR or MRM assemblies. The gypsum panels, preformed concrete panels, poured-in-place concrete or composite mass-weighted construction panels which are placed between the BUR or MRM assemblies and the roof substrate causes more gradual changes in temperature between the roof assembly and the roof substrate. Because the BUR or MRM assemblies, which are attached to the loose laid gypsum or the like panels, can move independently of the insulated roof substrate panels with the expansion and contraction concomitant thermal cycling, wrinkles and tears previously associated with the joint lines of the roof substrate panels are practically eliminated. Additionally, the weighted roof assembly of the invention aids in wind uplift protection by providing a floating, moveable mass under the BUR or MRM assemblies by distributing wind uplift shock away from the perimeter edge of the roof and into the interior thereof.

BACKGROUND OF THE INVENTORY 
This invention relates generally to roofing systems for buildings. More 
particularly, this invention relates to built-up roof (BUR) or modified 
roof assembly systems that eliminate or reduce the wrinkles, ridges or 
tears which, as a result of thermal cycling, tend to form at the joint 
lines of fixed roof deck panels typically employed in this type of roof 
system. Environmental changes can cause minimal to dramatic shifts in 
temperature thus seriously threatening the structural integrity of 
conventional roof systems by promoting wrinkling, ridging and tearing. 
Built-up roof (BUR) systems and modified roof membrane assembly systems are 
well known in the industry and are used in a variety of applications. 
Conventional prior art roof system technology for buildings and the like 
have relied upon rigidly fixing the built-up roof (henceforth referred to 
as BUR) or modified roof membrane (henceforth referred to as MRM) by means 
of mechanical attachment or direct adhesion to the underlying roof deck 
and/or insulation board panels installed on the roof structure. 
Unfortunately, these prior art methods resulted in the following problems 
or deficiencies. 
The temperature conditions caused within the roof by daily thermal cycling 
(surface temperatures can range from as low as the lowest environmental 
temperature to as high as 170.degree. F. under bright sun) or rapid 
temperature changes concomitant sudden storms, results in dissimilar 
expansion and contraction of the roof. Clearly such a condition is 
detrimental to structural stability. 
Over varying periods of time for individual roof assemblies, unequal 
expansion/contraction rates cause ridges and/or tears at joint lines 
between insulation panels or roof deck panels upon which the BUR or MRM is 
installed. A contributing factor to such roof conditions, other than shear 
torsional forces created by thermal cycling, is flow of the BUR or MRM 
materials in the joint areas in which thermal insulation is lesser than in 
the center of insulation or roof deck panels. The flow of materials 
exacerbates the ridging and tearing effect of temperature variations. 
Alternatively stated, the roof and/or insulating panels are generally 
constructed from insulative material because it is desirable that panels 
resist cold and/or heat transmission through their mass. In the joint line 
areas where the roof panels abut, internal and external temperatures can 
intermingle, creating the above described dissimilar expansion and 
contraction. This causes the expanding molecules of the BUR or MRM to move 
outwardly from the center of the underlying roof panel, upon which the BUR 
or MRM is installed, towards the outer edges of each individual underlying 
panel board. The adjoining panel board sections of the BUR or MRM assembly 
will also have a similar egress pattern out from the center of each 
underlying panel board as the BUR or MRM heats up. 
In the area where the panel boards adjoin, heat can dissipate through the 
joint into the interior of the building and thus the joint line area can 
be cooler. Outward thrust from roof material flow, in addition to cycling, 
causes wrinkles or ridges in the joint line area. 
Moreover, a rapid cooling such as occurs during and subsequent to a 
torrential downpour during a summer heating cycle, can cool the roof from 
about 150.degree. F.-170.degree. F. to 80.degree. F. or less in a very 
short period of time. Such rapid cooling causes immediate shrinkage of the 
roof membrane, thus causing a reverse stress in the joint line area of the 
BUR or MRM; again, detrimental to structural integrity. 
Alleviating the above discussed drawbacks of prior art roof assemblies is 
clearly of strong interest to the art. 
SUMMARY OF THE INVENTION 
The above discussed and other problems and deficiencies of the prior art 
are overcome or alleviated by the built-up roof (BUR) or modified roof 
assembly system of the present invention. In accordance with the present 
invention, a built-up roof (BUR) or modified roof assembly system is 
provided which comprises an additional layer (relative to prior art 
assemblies) gypsum panels, preformed concrete panels, poured-in-place 
concrete or mass-weighted composite panels or composite sheets or panels 
of which have been loose laid over a roof substrate. The additional layer 
provides two important advantages to the BUR or MRM assembly: first, the 
material acts as a temperature change buffer and second, the additional 
layer, not being rigidly fastened to the substrate, can expand and 
contract as a unit, more uniformly than individual insulation panels. The 
layer, therefore, allows the BUR or modified roof assembly to conduct heat 
to or receive heat from the thermal mass of gypsum, concrete or other, 
similar mass-weighted material which lies immediately below the BUR or 
modified roof assembly. The benefit hereof is, of course, to mitigate any 
speedy changes in overall temperature of the roof assembly. As one of 
skill in the art will appreciate, reducing the speed of contraction and 
expansion in a roof assembly will add to that assemblies longevity by 
alleviating the formation of wrinkles, ridges and tears. With respect to 
the second advantage of the invention, the additional layer is not fixedly 
attached to the roof substrate, but preferably individual panels of the 
layer are adhered or affixed to one another such that the entire layer may 
move as a monolithic unit independently from the underlying insulated roof 
substrate when the BUR or modified roof assemblies, positioned thereabove, 
expand and contract due to changes in temperature. Because of the 
monolithic movement of the assembly and space provided at the perimeter 
for expansion, them are essentially no areas in which ridges can form. 
The assembly of the invention and application technique greatly reduce the 
development of wrinkles that occurred at the joint lines of the prior art 
rigidly fixed roof deck insulation panels. In addition, this weighted roof 
assembly also aids in wind uplift protection by providing a floating, 
movable mass for the BUR or modified roof assembly. Wind uplift shock is 
known to be primarily concentrated at the roof perimeter edge. The 
assembly of the invention, however, is effective at transferring wind 
uplift to the interior of the roof. The structure and assembly as a whole 
is therefore far more sound. 
In addition, even if the gypsum concrete or other similar material weighted 
boards were not strapped, mechanically attached, or adhesively bound at 
their edge portions during installation, thermal transmission in these 
panel joint line areas would still produce only minimized ridges because 
the weighted panels employed in the invention are more stable than the 
underlying insulation or roof deck construction panels. The more uniform 
expansion and contraction caused by panels of this type is advantageous to 
the roofing industry. The aforementioned total assembly therefore 
mitigates the prior art BUR or MRM problems of the underlying joint line 
area ridging and tearing or cracking. 
The above-discussed and other features and advantages of the present 
invention will be appreciated and understood by those of ordinary skill in 
the art from the following detailed discussion and drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIG. 1, the prior art built-up roof (henceforth referred 
to as BUR) or modified roof membrane (henceforth referred to as MRM) 
assembly system is generally shown at 10. The structural building wall 12 
supports one end of structural roof beam or rafter or joist 14; metal, 
concrete or the like roof deck panels 16 are fastened to structural roof 
beam 14 by known means. Common and known BUR insulation layer 22 is 
installed or fastened rigidly to the roof deck panels 16 by known 
fasteners 18 or known conventional BUR membrane rigidly installed onto BUR 
insulation layer 22 by means of asphaltic adhesive (either cold or hot 
applied) 26. To complete the conventional installation, common wood 
blocking 28 is used at the perimeter edge of the building, usually 
anchored to the bearing wall 12 by known fasteners 30 and capped by 
standard known gravel stop metal edging 32 over which conventional known 
BUR flashing 34 is installed by known methods. Over a period of time, 
ridges and stress cracks 36 and 38 develop in the BUR membrane 24 at the 
insulation layer panel joint line areas 40 and panel joint line area 42 
where the insulation panel layer 22 meets the bearing wall 12 of the 
building. Ridging and cracking 36, 38 of the BUR assembly 24 results from 
the heating and cooling cycling of the day and night environment to which 
the BUR assembly 24 is exposed over time. The problems associated with the 
prior art BUR and MRM roof assembly systems can best be explained with 
reference to FIG. 2 and FIG. 3 which depict a plan view of a section of 
prior art roof showing the propagation of heat expansion and contraction 
stresses in the BUR or MRM assemblies when subjected to daily heating and 
cooling cycles. FIGS. 2 and 3 show conventional insulation or roof deck 
panels. In FIG. 2, a typical 4'.times.4' panel is represented generally at 
50 and a typical 4'.times.8' panel is shown generally at 52 during the 
course of the heating cycle of a typical day. In FIG. 3, the same two 
panels 50, 52 are shown during the cooling cycle of a typical afternoon 
and evening. 
In FIG. 2 as the BUR or MRM assembly molecules within thereof expand, the 
stress lines represented by dashed arrow lines 54 move out from the panel 
center 60 toward the joint line area 56. In FIG. 3, of course, the 
contraction stress lines represented by dashed arrow lines 58 move in from 
the peripheral joint line area 56 toward the center of the panels 60. 
There is a different expansion ratio between the BUR of MRM assembly when 
compared with the relatively stable roof deck or insulation panel to which 
the BUR or MRM assembly is rigidly attached. Therefore, only the BUR or 
MRM assembly can absorb the expansion and contraction stresses of the 
heating and cooling cycles to which the roof is subjected. Because of this 
phenomena, ridges and tears develop along the joint line areas 56. 
The built up roof(BUR) assembly system in accordance with the present 
invention is shown generally at 70 in FIG. 4 which is a partial 
cross-sectional view which parallels FIG. 1 (prior art BUR or MRM assembly 
system). Most of the elements of the BUR or MRM assembly system in 
accordance with the present invention are similar or the same as the prior 
art BUR assembly system discussed previously hereinabove and those 
elements that are the same will carry the same number as in FIG. 1 but 
will be designated with a prime. 
As discussed relative to the prior art roof system, structural building 
wall 12' supports one end of structural roof beam, rafter or joist 14'. 
Metal, concrete or the like roof deck panels 16' are fastened to the 
structured roof beam 14' by known means. Common and known BUR insulation 
panel layer 22' is installed or fastened rigidly to the roof deck panels 
16' by known fasteners 18' or known adhesive layer 20'. 
In the prior art BUR assembly system of FIG. 1, a known conventional BUR 
assembly 24 is rigidly installed onto BUR insulation panel layer 22 by 
means of asphaltic adhesive 26. In FIG. 4, however, in accordance with the 
present invention, a loose layer of gypsum, concrete or the like 
(preferably 1/2" thick gypsum panels) are placed between the BUR 
insulation panel layer 22' and the BUR assembly 24'. These weighted board 
panels 72 provide a thermal heat sink or cold sink for temperature 
stability. The conventional BUR assembly 24' is bonded directly and 
rigidly to this weighted board panel layer 72. The joint lines 74 between 
the weighted board panels 72 are preferably abutted to one another and 
adhesively or mechanically bonded during installation to make the weighted 
board panels act as an integral floating mass. Another method is to 
forcefully spread apart the weighted board panels 72 during installation 
providing a minimum 1/8" gap between the weighted board panels 72 and then 
fill this gap with adhesive or other known compound in order to tie the 
weighted board panels 72 together. Tying together of the weighted board 
panels 72 results in a floating modulus with uniform expansion and 
contraction forces which tend to keep the BUR assembly 24', which is 
installed rigidly to the underlying weighted board panel layer 72, from 
wrinkling, ridging or tearing at either the weighted board joint lines 76 
or the underlying BUR insulation panel layer 22' joint lines 36' and 38'. 
To complete the installation of the BUR assembly system in accordance with 
the present invention, common wood blocking 28' is used at the perimeter 
edge of the building, usually anchored to the bearing wall 12' by known 
fasteners 30' capped by standard known gravel stop metal edging 32'. 
Unlike the prior art BUR assembly system, however, an expansion and 
contraction channel 78 is provided. Channel 78 is provided to allow 
expansion of the weighted board panel layer 72 edges 73 at the outer roof 
perimeter and any penetrations of the BUR roof assembly system. 
Over channel 78 is a special expandable flashing member 80 that is capable 
of absorbing the expansion and contraction of the BUR assembly 24'. 
Flashing member 80 comprises a soft foam core layer 82 preferably 
comprising dense foam rubber such as neoprent backer. Flashing outer layer 
84 is then attached over the soft foam core layer 82 such that said outer 
layer 84 may "float" over layer 82. A special polymeric adhesive 86 (such 
as sonnolestic) which is capable of accommodating the diverse expansion 
and contraction of the metal gravel stop edging 32' along the roof 
perimeter edge. Soft foam core layer 82 is commercially available from 
building supply houses. 
The modified roof assembly system (MRM) depicted in FIG. 5A is quite 
similar to the BUR assembly system previously discussed in relation to 
FIG. 4 except that substituted for the conventionally known BUR assembly 
24' shown in FIG. 4, a known modified roof membrane assembly (hereinafter 
referred to MRM) 90 is employed. Since there is no need for the gravel 
stop metal edging 32' of FIG. 4, it is replaced with a metal casing edge 
92 (or other suitable material) and is made integral with the special 
expandable flashing member 80 which is capable of absorbing the expansion 
and contraction that occurs within the MRM assembly 90. 
As was previously discussed with reference to FIG. 4, the MRM assembly 90 
is attached rigidly by known methods to a loose layer of gypsum weighted 
board panels or the like 72' which are preferably tied together so as to 
act as an integral floating mass to accommodate expansion and contraction 
of the MRM assembly 90 affixed to the board panel layer 72'. However, a 
narrow portion of weighted gypsum board 96 along the perimeter of the roof 
or any penetration of the MRM assembly 90 is fixedly fastened by known 
fasteners 94 which anchor narrow weighted gypsum board 96 to common wood 
blocking 28" used at the perimeter edge of the building. Of course, the 
common wood blocking 28" is in turn anchored to bearing wall 12" by known 
anchor fasteners 30". Of course, the underlying elements of structural 
roof beam 14", roof deck panels 16" and insulation panel layer 22" are all 
made of known materials and assembled by known methods and fastened in the 
same manner as depicted and described in FIG. 4. 
MRM assembly 90 is sealed between weighted gypsum board panel layer 72" and 
rigidly fixed to anchor weighted gypsum board narrow portion 96 by the use 
of special sealing compound layer 98. Flashing member 80' is fixedly 
anchored to the outside peripheral edge or rigidly fixed anchor weighted 
gypsum board 96. Board 96 is endowed with a special polymeric adhesive 
compound 86' (such as caulk) which is capable of accommodating the diverse 
expansion and contraction of the metal coping edge 92. The special 
expandable flashing member 80' in this manner absorbs the expansion and 
contraction that occurs within the MRM assembly 90 at the perimeter of the 
roof and at the various penetrations of the modified roof membrane 
assembly system in accordance with the present invention. 
A special movable spring flashing detail to accommodate expansion and 
contraction of either a BUR assembly or MRM assembly is depicted in FIG. 
5B in accordance with the present invention. The rest of the roof is 
constructed similarly to that illustrated in FIGS. 4 and 5A except where 
the roof approaches the parapet or the type of wall. 
Metal rain shield anchor strip 100 is fastened by known fasteners 102 to an 
appropriate distance up the parapet or other wall. Sealing compound 104 
produces a weather tight seal between metal rain shield anchor strip 100 
and the parapet or other wall 106. The entire special movable spring 
flashing assembly is generally shown at 108. 
At the other end of special movable spring flashing assembly 108 is a metal 
flashing retainer and anchor strip 110 which is fastened by known 
fasteners 112 to a known nailer 114. Of course, both rain shield anchor 
strip 100 and flashing retainer and anchor 110 is a soft core layer 82' 
over which the flashing outer layer 84' may float so as to accommodate the 
diverse expansion and contraction that has been developed in the rest of 
the BUR or MRM assemblies. Such movements are thus dissipated into the 
movable portion 116 of the special movable spring flashing assembly 108 
without causing permanent wrinkles or tears in the rest of the BUR or MRM 
assemblies. 
While preferred embodiments have been shown and described, various 
modifications and substitutions may be made thereto without departing from 
the spirit and scope of the invention. Accordingly, it is to be understood 
that the present invention has been described by way of illustration and 
not limitation.