Support structure for mounting heavy objects

A support structure for the stationary, level mounting of heavy objects such as air conditioner condensers and the like. The support structure has a substantially flat top supported by sidewalls with an outwardly extending flange at the bottom edges of the sidewalls. The height and bottom edges of the sidewalls are fabricated to compensate for any slope in the supporting surface upon which the structure is to be rested so that the flat top is maintained substantially horizontal. The flange is parallel to the supporting surface so when the heavy object is rested on the flat top the weight is distributed over the area of the flange. The flat top and sidewalls form a closed surface and have a weather-resistant lamination that is continuous with the flange. If the object is to be roof mounted the flange may be substantially sealed to the roof surface so that moisture and debris do not contact the area of the roof underlying the support structure. Very little deterioration will occur to the underlying roof surface so that if reroofing subsequently becomes necessary, the materials can be applied directly over the flange so that the need to remove the support structure or mounted object is thereby eliminated.

BACKGROUND OF THE INVENTION 
This invention relates generally to support structures for the stationary 
level mounting of heavy objects such as air conditioner condensers and the 
like. More specifically the invention relates to support structures 
particularly well-suited for mounting such objects on inclined surfaces 
and especially building roof tops. 
To take advantage of unused space, air conditioner condensers and other 
heavy objects such as electrical transformers are frequently mounted on 
building roof tops. The roof top location also provides excellent air 
circulation that often aids in the operation of such apparatus. 
Because of the difficulties involved in supporting and anchoring these 
heavy objects, roof top mounting is most frequently done on flat roofed 
buildings. Roof tops are generally constructed only so as to be able to 
withstand the forces of winds and snow accumulation. Maximum loading is 
approximately 150 to 200 pounds per square foot and for this reason 
substantial support is required to prevent the weight of the objects from 
damaging the roof top. 
For roof mounting heavy objects one means of support frequently used is in 
the form of a steel frame, generally made from "I" beams or angle iron. 
The steel frame supports the object on legs that have been securely 
fastened to the underlying roof support structure, which is usually in the 
form of wooden roof beams or steel bar joists. The legs are made long 
enough so that the object is supported above the level of the roof top and 
the load is transmitted directly to the beams or roof support steel. 
The above-described form of support has several disadvantages. The 
installation of a steel frame is labor intensive and costly from the 
standpoint of materials. When a heavy object is to be mounted on an 
existing building, an opening must be made in the roof top to gain access 
to the underlying roof beams or support steel. The opening must be 
"framed-off" and well sealed to prevent water leakage into the underlying 
roof support structure. Also, if reroofing subsequently becomes necessary, 
it is difficult to refinish the surface underneath the steel structure due 
to the limited space between it and the roof top. 
Another practice of roof mounting heavy objects has been to fabricate a 
wooden support structure, similar to the steel structure described above. 
To protect the wood from weather and insects, the exposed portion of the 
support structure is encased in a metal shroud. Since the wooden support 
structure must also be anchored to the underlying roof beams or support 
steel and the metal shroud is subject to corrosion, water leakage is a 
frequent problem. 
A third practice of roof mounting has been to place a molded polyethylene 
pad on the roof surface and resting the heavy object on the pad. While 
weather-resistant, the molded polyethylene pad, cannot be readily adapted 
to meet the individual requirements of each installation. Air conditioner 
condensers and the like are desirably mounted so as to be horizontally 
level. Since most flat roofs have some slope (of varying degree) to aid in 
draining off water, some means of shimming the pad to the level position 
is required. The molds needed to manufacture the polyethylene pad are not 
easily retooled to compensate for individual roof slopes. 
Molded polyethylene pads have also been used to mount heavy objects at 
ground level. Again, some means of shimming the pad to the level position 
is required. 
Another practice for mounting heavy objects at ground level has been to 
fabricate a mounting pad from concrete. The pad must be constructed at the 
desired location and installation of the object delayed until the concrete 
has cured, thus necessitating the return of workmen to complete the 
mounting procedure. Since it is not economically feasible to supply 
ready-mixed concrete in small quantities several such pads are usually 
poured from a single truckload of concrete or the concrete is mixed at the 
mounting site. 
OBJECTS OF THE INVENTION 
The present invention is directed at overcoming the disadvantages and high 
cost associated with the previous support structures used for the 
stationary, level mounting of heavy objects such as air conditioner 
condensers and the like. 
It is therefore an object of the invention to provide an improved 
weather-resistant support structure whereby the weight carried by the 
support structure is distributed over a large area of the surface on which 
the structure is rested thereby eliminating the need to anchor the 
structure to any other support means. 
It is also an object of the invention to provide an improved 
weather-resistant support structure whereby the heavy object may be 
supported in a substantially level position without the use of shims. 
Another object of the invention is to provide an improved weather-resistant 
support structure for roof mounting heavy objects whereby reroofing may be 
done without removal of the object or support structure. 
Still another object of the invention is to provide a novel method of 
fabricating such an improved weather-resistant structure. 
These and other objects will become apparent to those skilled in the art 
from the following drawings, descriptions and appended claims. 
BRIEF DESCRIPTION OF THE INVENTION 
In accordance with the present invention an improved support structure for 
mounting heavy objects such as air conditioner condensers and the like is 
constructed. A wooden skeleton is formed by connecting supporting 
sidewalls to a substantially flat top. To maintain the flat top generally 
level the height of the sidewalls is varied and the bottom edges of the 
sidewalls sloped to compensate for any slope in the surface upon which the 
structure is to rest. The entire skeleton is laminated with a 
weather-resistant material to a predetermined thickness. The same 
weather-resistant material is used to form a flange that extends outwardly 
from the bottom edges of the sidewalls so the weight carried by the 
support structure may be distributed on the supporting surface over the 
area of the flange. 
As used herein a weather-resistant material is one through which moisture 
will not penetrate and which will not readily degrade and lose its 
effectiveness from long term exposure to outdoor elements such as 
precipitation and temperature fluctuations.

DETAILED DESCRIPTION OF THE INVENTION 
In accordance with the present invention an improved support structure 11 
for the stationary level mounting of heavy objects 13 such as air 
conditioner condensers and the like is constructed (FIG. 1 through 5). The 
object 13 rests directly on the load bearing surface 14 of the support 
structure (FIGS. 1, 2, 4 and 5) or on optional rubber isolator pads 41 
(FIG. 3) where its position is maintained by its own weight. The weight of 
the object 13 is distributed on the surface upon which the structure is to 
rest over the area of the flange 19. 
The support structure 11 comprises a wooden skeleton 15, a continuous 
weather-resistant lamination 17 over the wooden skeleton 15 and a flange 
19 that is continuous with the lamination 17 and fabricated from the same 
weather-resistant material (FIG. 3). The wooden skeleton 15 has a 
substantially flat top plate 21 supported about its entire periphery by 
sidewalls 23F, 23B, 23R and 23L that are generally normal to the plane of 
the top plate 21 (FIGS. 1 and 3). The skeleton 15 may be provided with 
additional strength by including one or more internal ribs 25 as shown in 
FIGS. 1 and 2. 
In the illustrated embodiment of the invention shown in FIGS. 1, 2 and 3 it 
can be seen that the top plate 21 has parallel top 26 and bottom 29 planar 
surfaces and a rectangular peripheral shape as defined by its edges 35. A 
rectangular shaped top plate 21 will accommodate most air conditioner 
condenser units and since it is fabricated from wood it may be cut to 
size. Rectangular dimensions of the top plate typically range from about 
24.times.36 inches to about 48.times.96 inches. The peripheral shape of 
the top plate 21 may, however, be varied to accommodate an odd-shaped 
object as discussed hereinafter in conjunction with FIG. 5. The sidewalls 
23F, 23B, 23R and 23L are generally rectangularly shaped and have parallel 
outside 33 and inside 37 planar surfaces with bottom 24, top 27 and 
vertical 36 edges normal to the planar surfaces 33 and 37. 
The relative positioning of sidewalls 23R with respect to the top plate 21 
is shown in FIG. 3 and is illustrative of all the sidewalls in this 
respect. The top edge 27 of sidewall 23R is contacted with the bottom 
surface 29 of the top plate 21 to form a simple butt joint 31. Since the 
top edge 27 is perpendicular to the outside planar surface 33 of the 
sidewall 23R, the outside planar surface 33 may be made flush with the 
edge 35 of the top plate 21. The internal rib 25 has a top edge 26 and 
vertical edges 28 that form similar butt joints 31 with, respectively, the 
bottom surface 29 of the top plate 21 (FIG. 2) and the inside planar 
surfaces 37 of sidewalls 23F and 23B (FIG. 1). Butt joints 31 are also 
formed at the corners of the wooden skeleton 15 by the vertical edges 36 
of sidewalls 23R and 23L and the inside planar surfaces 37 of the adjacent 
sidewalls 23F and 23B (FIG. 1). The butt joints 31 may be held together by 
a variety of fastening means (not shown) including nails, wood screws and 
adhesives. Each sidewall 23F, 23B, 23R and 23L is joined with its two 
adjacent sidewalls as well as the top plate 21 thereby forming a 
continuous closed surface. 
Once constructed, the wooden skeleton 15 receives the lamination 17 (FIG. 
3). While a main function of the lamination 17 is to provide the wooden 
skeleton 15 with weather resistance, a properly chosen material or 
composite may also impart it with considerable additional strength. A 
combination of polyester and chopped fiberglass filaments has been found 
to achieve both these results and may be spray-coated as a mud-like 
composite through the use of various commercially available pneumatic 
guns. The composite hardens with time thereby forming the lamination 17. 
Liquid polyester resin and a "hardening" catalyst are commercially 
available through suppliers and manufacturers such as Reichhold Inc. who 
sells products under the tradename "Polylite". Fiberglass filaments are 
supplied from fiberglass rope having individual filament diameters of 
about 0.00020-0.00029 inch. A pneumatic gun available from Binx Inc. 
("Maverick Model") automatically cuts the fiberglass rope to the proper 
filament length, mixes the fiberglass filaments, polyester resin and 
hardening catalyst in the proper proportions, and sprays the mud-like 
composite where directed. The thickness of the lamination may be built up 
by successive coats of composite, each preferably being approximately 1/16 
inch thick. A mixture of composite that is roughly 28-33 weight percent 
fiberglass provides excellent strength and weather resistance. 
Since the lamination 17 is used to impart both strength and weather 
resistance to the support structure 11, the entire skeleton 15 is 
spray-coated so that no wooden surfaces are left exposed and the 
lamination 17 is continuous over the support structure 11 (FIG. 3). This 
substantially seals the wooden skeleton from moisture and greatly extends 
its life. 
In the normal mode of manufacturing the support structure 11, the wooden 
skeleton 15 is first constructed. If the surface of the wood is very 
smooth it may be sandblasted to provide for better adhesion of the 
lamination 17. It is then inverted and all exposed interior wooden 
surfaces are spray coated including the bottom surface 29 of the top plate 
21, both faces 30 and bottom edge 40 of any internal ribs 25 as well as 
the bottom edges 24 and inside planar surfaces 37 of the sidewalls 23F, 
23B, 23R and 23L. Before the composite completely hardens, the wooden 
skeleton 15 is righted and placed on a flat surface that has been 
specially treated with a release agent or parting compound to prevent the 
composite from adhering to the surface. The dimensions of the surface used 
must be great enough so that the flange 19 may be formed thereon. The 
composite is then sprayed on the exterior surfaces of the wooden skeleton 
15 covering the top planar surface 26 and edges 35 of the top plate 21 and 
the outside planar surfaces 33 of the sidewalls 23F, 23B, 23R and 23L. In 
the same operation, a substantially uniform thickness of the composite is 
also sprayed on the flat surface about the periphery of the wooden 
skeleton 15, extending outwardly from the bottom of the sidewalls to form 
the flange 19 (FIGS. 1 and 3). Thus, as the composite hardens, the flange 
19 so formed bonds to and becomes continuous with the lamination 17 on the 
exterior and interior surfaces of the wooden skeleton 15. The flange 19 
may then be trimmed to a uniform width as shown in FIG. 1, typically about 
6 inches. 
If the weight of the object 13 intended to be supported warrants the 
load-bearing capacity of the structure 11 be increased, additional spray 
coats of composite may be used to increase the thickness of the lamination 
17 and the flange 19. Typically, the wooden skeleton 15 is spray coated 
until the lamination 17 is about 1/8 to about 3/16 inch thick. 
While standard 3/4 inch plywood is most often used to construct the wooden 
skeleton 15, the strength of a lamination 17 comprised of polyester and 
chopped fiberglass filaments is great enough so that the skeleton 15 may 
be built entirely from balsa wood. The porosity of the balsa wood causes 
it to absorb the polyester resin and hardening catalyst mixture while it 
is still in liquid form. After hardening, the strength of the balsa wood 
skeleton is greatly increased. Successive coats of polyester and chopped 
fiberglass are used to further increase the strength of the support 
structure 11 and to form the flange 19. Support structures with skeletons 
15 fabricated from balsa wood may be used to support smaller air 
conditioner condenser units that generally have a cooling capacity of 
about 10,000 B.T.U.'s. 
Air conditioner condensers that have a large cooling capacity (about 50,000 
B.T.U.'s) are generally much heavier and require a very sturdy support 
structure 11. For these applications the wooden skeleton 15 is fabricated 
from one inch thick, 17 ply Finnish birch. This material has a compressive 
strength of about 230 p.s.i. enabling it to impart extra load-bearing 
capacity to the support structure 11. 
Occasionally, it is desirable to allow for air flow beneath the supported 
object 13 or to dampen the transmission of vibrations from the object to 
the support structure 11. This can be accomplished by placing a plurality 
of rubber isolator pads 41 between the object 13 and the load-bearing 
surface 14 of the support structure 11 (one such rubber isolator pad 41 is 
shown in FIG. 3 only). The rubber isolator pads 41 may be fastened to the 
support structure 11 by pressing directly into the polyester and chopped 
fiberglass composite before it hardens so that it is embedded in the 
lamination 17. 
After the composite has completely hardened thereby forming the flange 19 
and the lamination 17 over the wooden skeleton 15 the support structure 11 
is complete. If the support structure 11 is used for roof mounting of an 
object 13, an underlayment 41 (FIG. 1) of ninety to one hundred pound felt 
roofing paper is laid directly on the roof surface at the desired mounting 
location. The support structure 11 is then placed on top of the 
underlayment 41. The underlayment 41 is positioned between the flange 19 
and the roof surface under the support structure 11. The object 13 is then 
rested directly on the load bearing surface 14 (FIG. 2) or the optional 
rubber isolator pads 41 (FIG. 3). The weight of the object 13 is 
distributed over the flange 19. The compressive stress exerted by the 
flange 19 is low enough so that very little damage results to the roof 
surface. The stress is, however, high enough so that the underlayment 41 
forms a moisture resistant seal between the flange 19 and the underlying 
roof surface. Since the lamination 17 is continuous over the entire 
surface of the support structure 11, the underlying roof surface will be 
substantially sealed from moisture and other debris. Consequently, the 
underlying roof surface will suffer very little deterioration with time. 
Thus, when reroofing of the exposed roof surface becomes necessary, the 
support structure 11 need not be removed. The reroofing material 43 such 
as tar may be placed directly over the flange 19 (FIG. 3). If it is 
determined that reroofing will be done shortly after installation of the 
support structure 11, the underlayment 41 may be omitted as the reroofing 
material 43 may be used to effect a moisture resistant seal. 
A second embodiment of the support structure 11, shown in FIG. 4, is 
constructed to provide level support for a heavy object on a sloped 
surface. In the modified skeleton 15' the general shape of sidewalls 23F' 
and 23B' (not shown) is trapezoidal. The slope of the bottom edge 24' on 
sidewalls 23F' and 23B' is equal to the slope of the supporting surface 
upon which the structure 11 is rested so that the load bearing surface 14 
remains generally level. The height of sidewall 23R' and the internal rib 
25' is increased proportionately. If the degree of slope is large the 
bottom edges 24' of sidewalls 23L' and 23R' as well as the bottom edge 40' 
of the internal rib 25' may have to be beveled so as to be coplaner with 
the bottom edge 24' of sidewalls 23F' and 23B'. The flange 19' is formed 
as previously described, and is then parallel to the sloped surface. 
A third illustrated embodiment of the invention is shown in FIG. 5. The 
skeleton 44 has a top plate 45 in the general shape of an octagon to 
accommodate a cylindrical object 13. The top plate 45 is supported by 
eight sidewalls 47 joined to the top plate 45 continuously about its 
periphery by butt joints 31. The sidewalls 47 are joined to one another by 
miter joints 49. For purposes of clarity, the weather-resistant lamination 
has not been delineated. The flange 51 extends about the entire periphery 
of the support structure 11 at the bottom edges (not shown) of the 
sidewalls 47. 
From the foregoing it should be appreciated that a novel apparatus for roof 
mounting heavy objects such as air conditioner condensers and the like and 
a method of constructing the same have been described. The support 
structure is fabricated so the load bearing surface has a shape and 
dimensions corresponding to the object to be supported. The bottom edges 
and shape of the sidewalls may be easily custom formed to compensate for 
roof slope so the load bearing surface is maintained substantially level. 
The weight of the mounted object holds both the support structure and the 
object in place. The weight of the object is distributed over a large area 
by a flange so that if the object is roof mounted very little damage is 
done to the load bearing roof surface, thereby eliminating the need to 
gain access to the underlying roof support structure for the purpose of 
transferring the load directly thereto. A weather-resistant lamination, 
continuous over the entire structure and a procedure for providing a 
moisture resistant seal between the load-bearing roof surface and the 
flange, allows the roof surface underlying the structure to be 
substantially protected from moisture and debris. Very little 
deterioration of the underlying roof surface will occur with time and if 
reroofing of the exposed roof becomes necessary, the reroofing material 
can be placed directly over the flange, eliminating the need to remove the 
mounted object or the support structure. 
It should be understood that although certain preferred embodiments of the 
present invention have been illustrated and described, various 
modifications, alternatives and equivalents thereof will become apparent 
to those skilled in the art and accordingly the scope of the present 
invention should be defined only by the appended claims and equivalents 
thereof. 
Various features of the invention are set forth in the following claims.