Roof insulation support

A roof insulation support for a building roof of the type having a parallel array of longitudinally extending roof supporting purlins, each of the purlins including a longitudinally extending upturned lip. The roof support comprises a plurality of elongated longitudinally extending hangers, each hanger including a generally vertical web and a hook disposed on the top of the vertical web for supporting the hanger from the upturned lip of the purlins. First and second lower hanger flanges depends from both sides of the bottom of the vertical web and first and second upper hanger flanges are spaced upwardly on the vertical web from the first lower flange. A plurality of transversely extending beams of roughly I-shape cross section extend between the hangers. The ends of the beams are received between the upper and lower hanger flanges of adjacent hangers. The beams include lower and upper beam flanges defining a vertical height equal to the spacing between the lower and upper hanger flanges of the hangers to torsionally stabilize the transversely extending beams. A plurality of planar roof insulation supporting panels are supported by the lower flanges of both the longitudinally extending hangers and the transversely extending beams.

BACKGROUND OF THE INVENTION 
The invention relates generally to insulated roof structures and more 
particularly to a roof insulation support for a metal building. 
In the construction of metal buildings, generally a plurality of 
transversely extending main roof support beams are provided for defining a 
peaked, sloped or flat roof. These transversely extending main roof 
support beams support a plurality of longitudinally extending purlins, the 
purlins being arranged in a generally parallel array. The purlins are of a 
channel or Z-shaped cross section and are usually provided with a 
longitudinally extending upturned lip disposed on the bottom of the 
purlin. The lower surface of the purlins is firmly secured to the 
transversely extending beams. Metal roof panels forming the exterior 
surface of the roof are then secured to the tops of the purlins. 
These types of metal roof building structures have been insulated by a 
number of prior art arrangements. For example, it is not uncommon for a 
layer of rolled insulation and/or a layer of rigid closed cell foam 
insulation to be laid over the tops of the purlins before the metal roof 
panels are secured thereto. Problems with this roof insulating arrangement 
stem from the fact that the batts or rivets that are used to secure the 
metal roof panels to the purlins provide a thermal "short circuit" causing 
the purlins to be in good thermal conductivity with the exterior surface 
of the building. In addition to increasing heating and cooling costs, in 
the winter condensation of moisture on the purlins can become a problem. 
Other problems with this type of roof insulation include difficulty 
providing a layer of insulation of sufficient thickness to achieve the 
high insulation factors desirable with todays high energy costs and 
difficulty in upgrading the insulation factor of existing insulation of 
this type. 
It has also been known to secure roof liner panels to the bottoms of the 
purlins with bolts, rivets, or the like and to fill the space between the 
roof liner panels and the metal roof panels with fiberglass insulation or 
the like. However, the process of attaching the roof liner panels to the 
lower flanges of the purlins by means of rivets or screws is a very time 
consuming one, resulting in high labor costs. Thus, a variety of prior art 
roof insulating systems evolved, employing longitudinally extending roof 
liner panel hangers which are provided with resilient clips for gripping 
the bottoms of the purlins. These hangers are generally provided with an 
inverted T-shaped cross section defining a bottom flange upon which the 
roof liner panels rest. The roof liner panels extended between adjacent 
hangers and, in some cases where the distance between hangers is great, 
transversely extending beams, also supported by the hanger flanges, are 
disposed between adjacent roof liner panels. These transversely extending 
beams are also provided with T-shaped cross sections to define lower 
flanges for supporting the transversely extending edges of the roof liner 
panels. 
While this latter type of roof insulation support system is easier to 
install then systems involving the attachment of roof liner panels with 
screws, rivets or the like, and in fact, this system can be retrofitted on 
an existing building structure, the resilient clips of prior art hangers 
often do not fit purlins of varying thickness or accommodate sections of 
the roof structure where the purlins were overlapped. In cases where the 
distance between purlins is great and additional support for the roof 
liner panels is provided by transverse beams, installation is made awkward 
by the poor torsional stability of the beams. The torsional stability of 
the transversely extending beams is important since if a transversely 
extending beam rotates during installation of the panels, a tight pack of 
the panels will not be achieved. Also, the poor torsional stability of the 
beams makes reentry into the insulated space for maintenance on pipes and 
other fixtures in the insulated space difficult since removal of one or 
more of the panels may loosen the packing of the panels, allowing one or 
more of the beams to rotate as the panels are manipulated. The poor 
torsional stability of the transversely extending beams hamper 
installation of the beams and made reentry into the insulated space 
somewhat more tedious. 
SUMMARY OF THE INVENTION 
These and other problems in the prior art are solved by provision of a roof 
insulation support comprising a plurality of elongated longitudinally 
extending hangers. Each of the longitudinally extending hangers comprise a 
generally vertical web, fastening means disposed on the top of the 
vertical web for supporting the hangers from the upturned lip on each 
purlin, and first and second lower hanger flanges and first and second 
upper hanger depending from the vertical web. The lower and upper hanger 
flanges depend from opposing sides of the vertical web, the upper hanger 
flange being upwardly spaced from the lower hanger flange and roughly 
parallel thereto. A plurality of transversely extending beams of roughly 
I-shaped cross section extend between the hangers. The transversely 
extending beams define a lower beam flange and an upper beam flange. The 
ends of the transversely extending beams are received between the upper 
and lower hanger flanges of adjacent hangers and the beams are provided 
with a vertical height equal to the spacing between the upper and lower 
hanger flanges. Thus, interference between the first lower and upper 
flanges of the longitudinally extending hangers and the second lower and 
upper flanges of the transversely extending beams torsionally stabilize 
the beams between the hangers. The planar roof insulation support panels 
are supported by the first and second lower flanges on adjacent pairs of 
longitudinally extending hangers and transversely extending beams, 
respectively. 
In more narrow aspects of the invention, the fastening means comprises a 
longitudinally extending hook formed from a generally vertical portion of 
the web extending above the first upper flange. A wall extends 
horizontally from the top edge of this generally vertical portion of the 
web and a longitudinally extending downwardly turned lip extends from the 
end of this wall. The downturned lip of the hook defines an oblique angle 
with respect to the generally horizontally extending wall such that the 
downturned lip roughly mates with the upturned lip of each purlin. The 
vertical portion of the web extending above the first upper flange extends 
a distance greater than twice the expected thickness of the purlins to 
accommodate overlapped purlins of varying thicknesses.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, the insulation support system of the present invention 
is generally indicated by the numeral 10. The insulation support includes 
a plurality of elongate longitudinally extending hangers 11 which depend 
from the upturned lips 12 of the purlins 13. In this case, the 
longitudinally extending purlins 13 are Z-shaped in cross section 
comprising a vertical wall 15 and top and bottom generally horizontally 
extending sections 16 and 17, respectively. The bottom sections 17 of the 
purlins 13 are supported by transversely extending beams not illustrated 
in FIG. 1. The top portions 16 of the purlins 13 support metal roof panels 
18 comprising the exterior surface of the building roof. A layer of closed 
cell foam insulation at 19 and a layer of rolled insulation at 20 are 
sandwiched between the purlins 13 and the panels 18. Typically, bolts, 
rivets or the like secure the metal panels 18, the closed cell foam 19 and 
the rolled insulation 20 to the top portion 16 of each purlin 13. 
The hangers 11 each comprise a generally vertical web 30, fastening means, 
generally indicated by the numeral 31, disposed atop vertical web 30 and 
first lower and first upper flanges 34 and 35, respectively, depending 
from the vertical web. The first upper and lower flanges 34 and 35 extend 
from both sides of the vertical web 30. The first lower flange 34 extends 
from the bottom of the vertical web 30 and the first upper flange 35 is 
spaced upwardly from the first lower flange 34. 
Referring now also to FIGS. 2, 3 and 4, it is illustrated that a plurality 
of transversely extending beams 40 are provided of generally I-shaped 
cross section. The transversely extending beams 40 extend between adjacent 
hangers 11, the ends of the beams 40 being received between the first 
upper and the first lower flanges 34 and 35 of adjacent hangers. The 
transversely extending beams 40 define lower and upper beam flanges 44 and 
45, respectively. The transversely extending beams 40 are provided with an 
overall height H.sub.1, best illustrated in FIG. 3, which is equal to the 
vertical spacing H.sub.2 between the lower and upper hanger flanges 34 and 
35 of the longitudinally extending hangers 11, best illustrated in FIG. 4. 
Since the ends of the transversely extending beams 40 are received between 
the first upper and lower flanges of the hangers 11, the transversely 
extending beams 40 are torsionally stabilized between adjacent pairs of 
longitudinally extending hangers 11, by interaction between the lower and 
upper hanger flanges 34 and 35 of the hangers 11 and the lower and upper 
beam flanges 44 and 45 of the beams 40. 
Referring now specifically to FIGS. 1 and 2, it is illustrated that the 
lower flanges 34 and 44 of the longitudinally extending hangers 11 and the 
transversely extending beams 40, respectively, support a plurality of 
generally planar roof insulation support panels 50. These roof insulation 
support panels or roof liner panels 50 are slid into place between 
adjacent pairs of longitudinally extending hangers 11. The opposed 
longitudinally extending edges 51 of the panels 50 are completely 
supported by the hangers 11 while the opposed transversely extending edges 
52 of each of the panels 50 is completely supported by the beams 40. The 
assembled insulation support defines an air space 60 between the outer 
metal panel 18 of the roof structure and the insulation support panels 50. 
This air space 60 is filled with any suitable type of insulation such as 
the fiberglass batt insulation, illustrated at 62 in FIG 1. The air space 
60 may be completely filled with fiberglass batting or other similar 
material or, as illustrated in FIG. 1, a single fiberglass batt may be 
provided to define an insulating air space between the outer metal panel 
11 and the fiberglass batt 62. The size of insulating space 60 may be 
varied by providing longitudinally extending hangers 11 with a vertical 
web 30 of varying length. 
Referring now specifically to FIG. 4, the fastening means 31 disposed atop 
the vertical web 30 of each longitudinally extending hanger 11 is 
illustrated in further detail. The fastening means 31 comprises a 
generally vertical portion 63 of the web 30 extending above the upper 
hanger flanges 35. A generally horizontal wall 64 extends from the top 
edge of the vertical wall 63. A longitudinally extending downwardly turned 
lip 65 extends from the edge of the generally horizontally extending wall 
64. A downturned longitudinally extending lip 65 forms an oblique angle 
.alpha. with the generally horizontally extending wall 64 such that the 
downturned lip 65 roughly mates with the upturned longitudinally extending 
lip 12, illustrated in phantom in FIG. 4, of each of the purlins 13. The 
horizontally extending wall 64 is spaced upwardly from the upper hanger 
flange 35 a distance H.sub.3 which preferably is equal to or greater than 
twice the thickness of the purlins 13. In this manner, the hook 31 may 
accommodate overlapped purlins and a wide range of purlin sizes. 
Preferably, the longitudinally extending hangers 11 are made of an extruded 
plastic material such as polyvinylchloride. The transversely extending 
beams 40 may also be manufactured from an extruded plastic material or, in 
the case where the loading on the panels 50 is quite high, and/or where 
transverse spacing between longitudinally extending hangers 11 is quite 
large, the beams 40 may be formed of steel. Preferably, the roof 
insulation support panels 50 are made of an acoustical insulation material 
so that in addition to improving the aesthetic appearance of the roof, 
reflected noise within the metal building is dramatically reduced. Also, 
preferably, the insulation support panels 50 are provided with a layer of 
impervious plastic or the like to act as a vapor barrier. This prevents 
water vapor from entering the air space 60 to condense upon the purlins 13 
which are in good thermal contact with the outer skin 18 of the metal 
building structure. The overall vertical height H.sub.1 of each of the 
transversely extending beams 40 and the spacing H.sub.2 between the lower 
and upper hanger flanges of each longitudinally extending hanger 11 is 
larger than the average expected thickness of the roof insulation support 
panels 50 so that the hangers 11 and transversely extending beams 40 will 
accept roof insulation support panels 50 having a wide range of 
thicknesses. 
The roof insulation support of the present invention may be installed in a 
preexisting metal structure to reduce heat loss through the roof and to 
prevent condensation on the purlins which are in good thermal contact with 
the outer metal skin of the roof. Such an installation is depicted in FIG. 
1. For example, FIG. 1 illustrates a typical preexisting metal roof 
structure having a layer of closed cell foam 19 and rolled insulation 20 
sandwiched between the tops of purlins 13 and the outer metal panels 18 of 
the roof structure. When such a retrofitting installation operation is 
desired the longitudinally extending hangers 11 are simply hung from the 
longitudinally extending purlins 13. Transversely extending beams 40 and 
the insulation support panels 50 may then be installed. Preferably, at 
least one linear transversely extending array of panels 50 and 
transversely extending beams 40 should be installed to torsionally 
stabilize the longitudinally extending hangers 11. Then, a longitudinally 
extending array of insulation support panels 50 with transversely 
extending beams 40 disposed therebetween may be formed between adjacent 
pairs of longitudinally extending hangers 11 by alternately sliding beams 
40 and panels 50 between flanges of the hangers 11 and packing the same in 
a longitudinally extending array. The air space 60 thus defined between 
the outer metal panel 18 of the roof structure and the insulation support 
panel 50 is then filled with a suitable insulating material such as 
sections of fiberglass batting illustrated at 62 in FIG. 1. 
In the case where the insulation support of the present invention is being 
added to a metal building structure during its initial construction, it is 
possible to install the insulation support after the purlins have been 
mounted to the tops of the transversely extending beams of the roof 
structure and before the outer metal panel 18 have been secured to the top 
of purlins 13. In this case, fiberglass batting 62 or other suitable form 
of insulation to be disposed in the air space 60 will be rolled or poured 
into place before the outer metal panels 18 are secured to the top of the 
purlins 13. 
The above description should be considered as exemplary and that of the 
preferred embodiment only. The true spirit and scope of the present 
invention should be determined by reference to the appended claims. It is 
desired to include within the appended claims all modifications that come 
within the proper scope of the invention.