Note: Descriptions are shown in the official language in which they were submitted.
~LX97X~7
LA: A-17839
--1-- '
OOF PAV~R CONNECTOR I~ND SYSTEM
sackground of the Invention
The present invention relates to a roof paver
element and a roof paver system including a plurality of
interconnected roof paver elements for covering roo~s
and, especially, for covering the membranes of single-
ply roofing systems.
For most types of low-slope roofs, roof ballast is
used to hold down the roofing membrane against the roof
deck when wind conditions may create negative pressures
tending to lift the membranes. The ballast also protects
the membranes from ultraviolet radiation and puncture or
impact damage by maintenance crews and wind-blown ob-
jects. The standard form for roof ballast has tradi-
lS tionally been a smooth, round "river wash" type of gravel
which is spread uniformly to produce a minimum of 10 lb/sf(237 kg/m2) load on the membrane. However, the use of
gravel as roof ballast has been reviewed in recent years
in light of the development of new single-ply roofing
systems and the extensive damage caused to buildings near
gravel ballast roofs as the result of flying gravel in
hurricane type conditions. New single-ply roofing mem-
branes, as opposed to the conventional multi-ply "built
up" roofing systems, do not use hot bitumen for holding
,ip. 25 the membranes in place, and in some cases, the single-ply
membranes are laid loosely on the roof deck without
fasteners other than at the perimeter, which means that
heavier than usual ballast is desirable to keep the
membralle down. In addition, because the gravel ballast
does not adhere to the single-ply membranes as it adhered
~- to the bitumen in the asphalt-based systems, there is a
129725~7
greater potential hazard of gravel flying under extreme
wind conditions.
In order to overcome the drawbacks of gravel
ballast, flat concrete paver elements and systems have
been developed which provide adequate ballast to hold
down the roof membrane and protect it from ultraviolet
radiation and impact damage, but each suffers from at
leastone of several disadvantages. Some of the prior art
roof paver elements require for their manufacture spe-
cial concrete molding equipment, drying racks and han-
dling equipment, even though they are produced by manu-
facturers already having conventional equipment of the
same types for producing standard concrete blocks. This
is due to the fact that the designs of the known paver
elements require the elements to have non-standard di-
mensions to provide roof drainage or for other purposes,
and even with such special dimensions, the provision for
roof drainage is not always adequate and/or permits
drainage in only one direction. Roof paver elements have
flat upper surfaces which allow air to flow uninterrupted
across the elements at high speeds, producing negative
pressures which can lift and displace the elements. In
addition, known roof paver systems do not provide a
convenient arrangement for aligning and anchoring the
paver elements in courses around the perimeter of the
roof or a system for preventing the paver elements from
sliding when they are installed in roofs having slopes
higher than 1 inch per foot.
~l2~7257
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Sumlnary of the Invention
In accordance with the present invention, a roof
paver system includes roof paver elements which can be
produced in a standard concrete block mold machine, dried
on standard drying racks and handled with conventional
concrete block material handling equipment. The length
and height of the paver elements correspond to two of the
dimensions of a standard concrete block mold machine, and
the width of the elements is such that a plurality of such
elements can be accommodated at one time in the mold.
Each roof paver element has a larger footprint
than previously known roof pavers, that is, a larger
proportion of its surface area contacts the roof to
provide a greater weight distribution and a reduced
likelihood of damage to the roof membrane or its sub-
strate. The roof paver elements according to the present
invention allow a far greater drainage volume than other
roof paver elements by providing more and larger drainage
grooves, and they permit the drainage in two directions.
The elements have a higher thermal insulating value than
previously known roof paver elements by their ability to
trap a larger volume of air in the drainage grooves, and,
by tapering alternate drainage grooves, the roof paver
elements provide a mechanism for immediately breaking
the vacuum between the elements and the concrete mold
when the elements are formed, thereby reducing forces
which retain completed elements in the mold and in-
creasing the speed and ease with which the elements can
be molded.
The ends of the elements cooperate with one an-
other to define composite drainage grooves for receiving
and retaining separate connecting members or interlock-
ing the elements to provide an integrated roof paver
system, thereby preventing individual elements from be-
ing lifted and moved out of position by high winds or
.
~7;~5~
traffic. The drainage grooves within each element which
are not tapered are shaped like the composite grooves,
providing a relatively narrow space at the roof membrane
but increased area above for greater drainage. The
efEect of high winds is also diminished by the provision
of raised portions on the top surface of each roof paver
element for generating air vortices to break up the
smooth flow of air which tends to lift the elements as it
moves across them. The raised portions also define a
safety tread which helps prevent workmen from slipping.
For some installations, such as those roofs hav-
ing a low perimeter fascia, the roof paver system employsclips along its perimeter for aligning the roof paver
elements at the start of laying and for anchoring them to
the roof. For roofs having high slopes, the system
includes elongate battens securable to the roof membrane
and shaped to be slid into and retained in the shaped
alternate grooves of the paver elements, the battens
having apertures to accommodate transverse stop members
for abutting the downslope edge of the paver elements.
A preferred connector has a tubular body portion
to allow drainage and includes flange stops projectiny to
engage the ends of ribs defining the drainage grooves in
the roof paver elements. The flange stops are positioned
closer to one end of the connector member than the other
to facilitate the connection of one end of a roof paver
element, in which the ends of the ribs are flush with a
generally planar portion of the element, with the oppo-
site end of an adjacent roof paver element, in which the
ends of the ribs are recessed from the planar portion,
thus preventing the connector from being inserted too
deeply into one paver and not sufficiently into its
adjacent mate. The connector member has a cross-sec-
tional shape providing a large area of engagement between
the connector member and the surfaces of the paver
-
7257
elements defining the groove. Resilient ridges project
from the connector member at its ends and engage sub-
stantial areas of the groove-defining surfaces to resist
removal from the groove, especially when the wind tries
to lift one of the paver elements relative to the others.
The ridges can be formed as a part of the body portion,
and the entire connector member can be made of a resilient
material, such as polyethylene. The ridges render the
connector member far more resistant to removal than
ridgeless connector members of the same configuration
while providing additional reinforcing against buckling.
~t some locations on a roof, it is desirable to orient the
grooves of some paver elements perpendicular to the
grooves of adjacent paver elements. The connector member
has one end which is bevelled to mate with a sloped
surface on an end rib of a paver element whose ribs are
perpendicular to the ribs of the adjacent paver elements
receiving the opposite end of the connector member. The
connector members have indicia for indicating the proper
direction for inserting the connector member into the
grooves in most instances.
~L~97Z57
--6--
Brief Description of the Drawings
Fig. 1 is a perspective view ofa roof paver system
in place on a roof;
Fig. 2 is a perspective view o~ a roof paver
element according to the present invention;
Fig. 3 is a top view of the roof paver element of
Fig. 2;
Fig. 4 is a partial front view of the roof paver
element of Fig. 2;
Fig. 5 is a cross-section taken along the line 5-5
in Fig. 4;
Fig. 6 is a side view of a perimeter clip according
to the present invention;
Fig. 7 is a schematic cross section of a roof paver
system installation employing the perimeter clips of
Fig. 6;
Fig. 8 is a schematic cross section of another
roof paver system installation;
Fig. 9 is an end view of a batten according to the
present invention;
Fig. lO is a side view of a preferred connector
member f~r the roof paver system according to the present
invention and portions of two roof paver elements;
Fig. ll is a cross section taken along the line
ll-ll in Fig. lO, showing the connector member in place
in a drainage groove defined between two other roof paver
elements;
Fig. 12 is a bottom view of the connector member
of Fig. lO;
Fig. 13 is a partial enlarged view of ridges shown
Oll the connector member of Fig. lO;
Fig. 14 is a perspective view of the connector
member of Fig. lO in position at the juncture of roof
paver elements; and
~;~97257
Fig. 15 is a side view of t~e connector member of
Fig. lQ connecting paver elements in which the drainage
grooves oE the paver elements are in alignment.
12972S7
Detailed Description of the Preferred Embodiments
-
In Fig. 1 of the drawings, an exemplary embodiment
of an integrated roof paver system 10 according to the
present invention is shown in place on a roof 12, in which
a roof membrane 14 overlies insulation 16 on top of a roof
deck 18. The roof paver system 10 includes a plurality
of roof paver elements 20, four of which are shown, each
of which contains a plurality of tapered grooves 22 and
alternating dovetail-shaped grooves 24 on the underside
to allow the drainage of water and to trap air for thermal
insulation. In addition, the dovetail grooves 24 receive
connector members 26, such as standard one-inch plastic
tube connectors, to positively interlock the roof paver
elements 20 in the system 10, and dovetail-shaped battens
28 to secure the paver elements 20 to the roof 12 and to
keep the paver elements from sliding on roofs having a
relatively high slope. In the embodiment illustrated,
the courses of roof paver elements 20 are staggered to
permit total interlocking of the roof paver system 10,
but it is understood that the roof paver elements 20 of
adjacent courses can be in alignment if desired.
As can be seen from Fig. 2, the roof paver element
20 is a thin shell block element preferably made of
concrete and having dimensions which permit it to be
molded readily in a standard concrete block mold box. For
this reason, a preferred embodiment of the roof paver
element has nominal dimensions of 16 in. x 8 in. x 2.5 in.
so that a mold box which can produce, for example, three
standard concrete blocks at a time can produce eight thin
shell roof paver eiements at a time. A roof paver element
20 according to the present invention having the above
dimensions has a ballast weight of 11 pounds per square
~2972S7
foot, a coverage of .88 square feet, a footprint of 81.5
square inches per square foot of coverage (56~), and an
insulating value of 1.6 R (sf). The roof paver element
20 includes an elongate planar portion 30 which defines
the upper portion of the paver element 20 when it is in
place on a roof, and projecting from tlle planar portion
30 are a plurality of spaced ribs 32 terminating in
broadened feet 34 and 36 which include toe portions 34a
and 36a, respectively, and heel portions 34b and 36b. The
area of the feet 24 and 26 which contacts the roof, that
is, the footprint, is made greater than the cross-sec-
tional area of the ribs 32 to provide increased weight
distribution and to diminish the likelihood of damage to
the roof membrane or its substrate. The dovetail grooves
24 are defined between adjacent ribs 32 and facing toe
portions 34a and 36a of the feet 34 and 36, so that the
region above the toe portions 34a and 36a has an increased
cross-sectional area to accommodate a large volume of
drainage. The tapered grooves 22, which are defined
between adjacentribs 32 and the heel portions 34b and 36b
of the feet 34 and 36, taper longitudinally to provide a
mechanism for breaking the vacuum between the tapered
grooves 22 and the mold as the roof paver elements 20 are
slid out of the mold in a direction parallel to the
grooves 22 and 24. The breaking of the vacuum between the
tapered grooves 22 and the portions of the mold they
contact reduces the overall forces retaining the paver
elements 14 in the mold so that the elements can be slid
out easily.
The feet 34 and 36 are shorter than the parallel
dimension of the planar portion 30, each foot having a
flush end 38 which is coplanar with an edge of the planar
portion 30 and a recessed end 40 which is connected by a
bevelled portion 42 of the ribs 32 to an opposite edge of
the planar portion 30, as can best be seen from Figs. 1
~ ~,~5,7
--10--
and 2. When the paver elements 20 are in place on a roof,
the space between the recessed ends 40 of the feet 34 and
36 and the adjacent edge of the planar portion 30 define
with the bevelled portions 42 of the ribs 32 a drainage
passage which is transverse to the drainage provided by
the dovetail grooves 24 and the tapered grooves 22. Fig.
1 shows in dotted lines a transverse drainage passage 44
of double width defined by the juxtaposition of the
recessed ends 40 of the feet 34 and 36 of one paver
element 20 with the recessed ends 40 of the paver elements
20 in the adjacent course. sy this arrangement, a double
width transverse drainage passage 44 is defined after
every two courses of paver elements 20, there being no
significant transverse drainage at the abutment of the
paver elements between the drainage passages 44. The
paver elements 20 can also be laid with the recessed ends
40 in each paver element 20 juxtaposed with the flush ends
38 of the feet 34 and 36 of paver elements 20, so that a
transverse drainage passage of single width is defined
after every course of paver elements 20.
As can best be seen from ~igs. 1 and 3, the roof
paver elements 20 have bar-shaped raised portions 46 on
their upper surfaces, so that when the roof paver ele-
ments 20 are in place on a rooe, the raised portions 46
provide a tread for roof traffic, such as maintenance
crews and repairmen, and also constitute vortex gene-
rators which break up the flow of air along the roof paver
elements, which can cause uplift and displacement of the
elements, by creating swirls of air which reduce the
negative pressure causing the uplift.
Each paver element 20 terminates at its ends with
structure defining one half of a dovetail groove 24.
Specifically, each end of the paver element 20 includes
a rib 32 spaced inward from the lateral edge of the planar
portion 30 by a distance equal to one half the width of
a dovetail groove 24 and a foot 34 or 36 having an
725~
outwardly directed toe 34a or 36a, so that when the end
of the paver element 20 is laid in abutment with the end
of the adjacent paver element, a composite dovetail
groove 24 for receiving the connector members 26 is
defined, as can be seen in Fig. 1. The connector members
26, which are received snugly between aligned dovetail
grooves 24 in adjacent roof paver elements 20 further
prevent the displacement of the elements. The dovetail
grooves 24 which lie entirely within one roof paver
element 20 also can receive the connector members 26, as
shown in Fig. 1, so that a connector member can have one
end inserted in a composite dovetail groove 24 and the
other end inserted in a dovetail groove 24 lying entirely
within one roof paver element 20. The connector members
26 can also connect two dovetail grooves 24 lying en-
tirely within their respective roof paver elements 20
and, where the roof paver elements of adjacent courses
are in alignment, the connector members 26 can connect
two composite dovetail grooves 24.
Especially in cases where the connector members
26 are used in dovetail grooves 24 defined entirely by one
roof paver element 20, stops, such as radial projections
37, for engaging the ends of the ribs 22 or feet 34 and
36 are provided to prevent the connector members 26 from
being pushed too far into the dovetail grooves 24 in a
roof paver element 20 in one course by the e]ement in the
next course as it is being moved into abutment with the
element in the first course. Although connector members
26 are employed in only two of the dovetail grooves 24 in
each roof paver element 20 illustrated in the embodiment
of Fig. 1, any number of the remaining dovetail grooves
24 can be employed to receive additional connector mem-
bers 26 if stronger integration of the roof paver ele-
ments 20 is desired.
In order to allow the alignment of the roof paver
elements 20 at the perimeter of the roof paver system 10,
~72~7
-12-
and to anchor the elements in place, anchoring and
alignment devices such as the clip 48 illustrated in Fig.
6 are provided. The clip 48, which can be made, for
example, of metal or plastic, includes a base portion 50
having at least one aperture 52 for receiving nails or
other fasteners, an angular portion 54 shaped to mate
with the outwardly directed toe 36a at the end of a roof
paver element 20' and a fascia portion 56. As can best
be seen from Fig. 7, in which a portion of the roof paver
system 10 is shown on a roof, the clips 48 can be nailed
to a nailer 58 at the top of a wall 60. The fascia portion
56 extends down past the side of the nailer 58 and
terminates in an inwardly directed hook portion 61, which
engages the wall 60. A membrane 62, which overlies
insulation 64 on top of a roof deck 66, can also overlie
the base portion 50 of the clips 48 which have been
secured to the nailer 58. The clips 48 constrain the end
of the perimeter course roof paver element 20', which in
this case is one half of the element 20 shown in Fig~ 2
and is laid perpendicular to the course of roof paver
elements inside the perimeter course. The dovetail
grooves 24 of the roof paver elements 20' in the perimeter
course can be secured to one another by the connector
members 26, and the elements 20' of the perimeter couxse
can be connected to the inner elements 20 by connector
members extending from the dovetail grooves 24 of the
inner members and received perpendicularly in the one
half dovetail groove, between the toe 34a and the lower
surface of the planar portion 30,defined at the inner end
of tlle elements 20'. Fig. 8 shows another installation
of a roof paver system 10' on a roof having a parapet 68,
including flashing 70 and counterflashing 72, for which
the perimeter clips 48 are not needed.
As is illustrated in Fig. 1, the roof paver system
10 can also include the elongate battens 28 for holding
down the roof paver elements 20 and for preventing them
~7257
from sliding, especially on roofs having a relatively
high slope. The battens 28 can be made of metal or
plastic, for example, like the clips 48 and include a base
portion 76 including a plurality of spaced apertures 78
for receiving nails or other fasteners to secure the
battens 28 to the roof. The dovetail shaped grooves 24
of the roof paver elements 20 are slidingly received on
the battens 28, which have a complementary portion 80
dovetail shaped in cross section, by which the battens 28
hold the paver elements 20 down. The battens 28 include
a plurality of spaced transverse openings 82 defined, for
example, in the dovetail portion 80 and sized to receive
a nail 84 or other thin element which engages the ends of
the ribs 32 or feet 34 and 36, thereby preventing the
paver elements from sliding along the battens 28.
Although the roof paver element is described
herein as being made of concrete, other suitable mate-
rials may be employed, such as ceramics or plastics.
Furthermore, the roof~paver elements may be employed in
structures other than as a part of a roof paver system.
An embodiment of a connector member which is
especially well-suited for connecting roof paver ele-
ments 20 according to the presentinvention is designated
generally by the reference numeral 90 in Figs. 10-~ff. As
can best be seen from Figs. 10-13, the connector member
90 is tubular and has the cross-sectional shape of a
truncated triangle, wherein the corners of the triangle
are missing in favor of short joining walls 92 and 94
joining three main walls: a bottom wall 96 and side walls
98 and 100.
A plurality of resilient ridges 102 project lat-
erally at the ends of the connector member 90 from the
side walls 98 and 100 and from the joining wall 94, which
joins the side walls 98 and 100 so that the connector
member 90 engages substantial areas of the portions of
the roof paver elements 20 defining the dovetail grooves
~lX~7~
-14-
24. As can best be seen from Figs. 10 and 13, each ridge
102 includes a surface 104 projecting substantially
perpendicularly from the side walls 98 and 100 and the
joining wall 94, and a surface 106 extending at a low
angle to the side walls 98 and 100 and the joining wall
94 from a line at or near the end of the connector member
90 toward the axial center of the connector to meet the
substantially perpendicular surface 104 and thereby de-
fine an edge. The shape of the ridges 102 permits the
connector member 90 to be slid easily into the dovetail
shaped grooves 24 of the roof paver elements 20 and allows
roof paver elements to be slid over a connector member 90
which is already in place on a roof, since the ridges 102
deform easily in that direction, but prevents the con-
nector member 90 from sliding out of a dovetail groove 24,since the ridges 102 do not deform easily when the
perpendicular surfaces 104 face in the direction of
movementand the sharp edges of the ridges 102 bind on the
paver element surfaces defining the dovetail groove 24
when the connector member 90 is moved in a direction out
of the dovetail groove.
The joining walls 92 have exterior surfaces
parallel'to and resting on sloped surfaces 108 on the toe
portions 34a and 36a of the ribs 32 of the roof paver
elements 20. In addition, the joining wall 94 is parallel
to an undersurface 110 of the planar portion 30, which is
oriented at an acute angle with respect to the sloped
surEaces 108. Thus, there is a significant area of
contact on three sides of the connector member 90 between
the connector member and the roof paver elements 20,
which is in contrast to the line contact which would occur
between a connector member of circular cross section and
the roof paver elements 20.
When any of the roof paver elements 20 are tilted
with respect to the connector members 90, as would occur
2~i'7
-15-
wilen tlle wind lifts a roof paver element, the connector
melnber 90 binds even more tightly against tlle roof paver
elements 20.
Stop elements in the form of flange stops 112
project from the joining walls 92 to engage the ends of
the ribs 32 oE the paver elements, as can best be seen in
Fig. 11. ~s is shown in Fig. 14, the flange stops 112 are
positionea closer to one end oE the connector member 90
tllall tl)e other to assure that both ends of the connector
member 90 extend into their respective dovetail grooves
24 whell connecting an end of a roof paver element 20 at
wllicll tlle ends of the ribs 32 are flush Witll the edge oE
the body portion, or planar portion, 30 with an end of a
rooE paver element 20 at which the ends of the ribs 32 are
recessed from the edge of the planar portion 30. Tlle
positioning of the flange stops 112 is such tllat tlle
connector member 90 extends equally into all of the
dovetail grooves 24. More specifically, the flange stops
112 are ofEset from tlle longitudinally axial center of
the connector member 90 by a distance equal to one half
the distance between recessed ends of tlle ribs 32 and the
adjacent edge of the body portion 30. Tlle flange stops
11211ave a curved periphery so tllat tlle connector members
90 can be molded without requiring mold recesses wllich
are di~ficult to keep clean, and tlle connector members 90
are well suited to be made of plastic, SUCIl as poly-
etl~ylene.
Indicia 11~, such as an arrow and the word "IN-
S~I~T", are provided on the connector member 90, Eor30 exan1ple, on the side wall 98, to indicate tlle end of the
conllector member to be inserted into the flushends of the
paver elements 20. On the opposite side wall, side wall
100, identifying information can be molded, such as a
tradelllark. "ROOFC~P", wllicll is shown in Fig. 15, is a
tradenlark of the National Concrete Masonry ~ssociation,
1~7~S7
the assignee of the present application~ ln order to
- provi~e connection between paver elements 20 when the
dovetail grooves 24 of some paver elements 20 are per-
pendicular to the dovetail grooves 24 o adjacent paver
elenletlts 20, one end of the connector member 90 includes
a c~lalnEer or bevel 116 defined by the bottom wall 96, the
joining walls 92, and portions of the side walls 98 and
100, the angle of the bevel 116 corresponding to the angle
of the sloped surfaces 108 on the toe portions 34a and 36a
of the ribs 32. ~s a result, as can best be seen in Fig.
15, the connector member 90 extends all of the way into
a recess defined by tl~e sloped surface 10~ and tlle
undersurface 110 of the planar portion 30 and engages a
vertical surface 118 of the rib 32 between tlle sloped
sur~ace lOa and tlle undersurface 110, in addition to
llavillg a substantial area of contact Witll tlle sloped
surface 108. When the connector mem~er 90 is in SUCII a
position, the ridges 102 engage the undersurface 110 of
t tl~e planar portion 30. Any lifting or tilting of the roof
paver element 20 engaging tlle bevelled end of the con-
nector melnber causes the angled edges on the ridges 102
to engage tlle undersurface 110 more tightly and tllereby
resist the separation of the roo~ paver element 20 from
tlle conllector member 90.
'l'hus, it will be appreciated tllat as a result o~
the invention, a higllly effective roof paver element and
system is provided for covering roofs, and that it will
be apparent to those skilled in the art and it is
contemplated that variations and/or changes in the em-
bodimellts illustrated and described herein may be made
without departure from the present invention. ~ccord-
ingly, it is intended that tlle foregoing description is
illustrative only, not limitin~, and that the true spirit
and scope of tlle present invention will be determined by
tlle appel-ded claims.
