Note: Descriptions are shown in the official language in which they were submitted.
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ENERGY DISSIPATION STRUCTURE
FOR SECURING LIGHTWEIGHT ROOFING ELEMENlS
For many years it was the universal practice to
construct roofsi with a waterproo~ layer or membrane on
the outer surface thereo~. Sueh roo~ing is still used
in many installations, but has many disadvantages. The
waterproof membrane, which may be built-up sheet
materia} and asphaltic or bitumin, or which may be a
single sheet o~ waterproo~ material, is exposed to
extreme temperature variations, as much as 200F, to
ultraviolet radlation, and to physical abrasion, all o~
- which have a detrimental ef~ect on the life o~ the
roofing.
It has baen common practice for many years to
provide insula'cion in roof construction, and when
insulation i~ provided below th~e waterproof membrane,
in the roofing system outlined above, it is necessary
to provide a second waterproo~ membrane below the
insulation to pr0vent moisture from within the building
from condensing in the insulation and inhibiting or
d stroying the insulating qualitie
An alternative up-side down roo~ing
construction i~ known in which the insulation is
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applied over the waterproof membrane, qee for example
U.S. Patents 3,411,256 and 3,763,614. In this
alternative roof construction the waterproof membrane,
which may be a built~up membrane or a single waterproof
layer such as a thermoplastic or an elastomer, is
~ applied directly to the surface of the roof. Blucks of
foam plastic insulation are then applied over the
waterproof me~brane. STYROFOAM (Trademark of The Dow
Chemical Company) brand foam polystyrene plastic
insulation is a superior product for such use. It is a
tough, closed-cell, rigid plastic foam having excellent
moisture resistance and high compressive strength.
The foam polyqtyrene plastic insulation placed
over the waterproofing membrane rather than under the
membrane protects the membrane from the effects of
thermocycling, temperature extremes, and physica~
abuse, thus reducing maintenance and prolonging the
life of the entire roofing system. It ha~ been found
that the membrane so protected remains stable at
temperatures below 100F even in hot summer weather. In
fact, under normal conditions, the temperature of the
membrane will remain within 15 to 20F of the building's
inside temperature.
Typically, a polymeric fabric is installed over
the foam to stabilize the system, and crushed stone or
gravel ballast is applied to counteract the buoyancy of
the insulation boards, to provide flammability
resistance to the roof surface, and to shield ~he foam
and fabric from ultraviolet radiation. As an
alternative, paving blacks may be used in place of
stone, particularly if traffic is to be expected on the
roo~.
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In some such inverted roofing installations ut:llizing
lightweight concrete paving blocks over foam plastic insulation,
there is a tendency for the wind to lift the paviny blocks and
insula~ion, and even to blow them from the roof deck. This is
particularly true if each paving block and insulation slab is not
thoroughly anchored to the roof deck. The situation can be
particularly bad when the foam insulation and lightweight paving
blocks are placed over unattached, single-ply membranes. The
single-ply membranes can be pressurlzed from below, due to
building pressures and/or wind pressure getting beneath the
membrane. When such pressurization occurs, the membrane will tend
to blllow or to form a balloon, and dump ~he paving blocks and
insulation off the sur~ace and expose them to the wind.
It would be desirable to utilize energy dissipation
means anchoring llghtweight concrete paving blocks on top of foam
plastic insulation in an inverted built-up roof system.
More particularly, it would be desirable to provide
energy dissipation means which is anchored to the underlying
waterproQfing membrane wlthout interrupting the lntegri~y of the
waterproofing membrane lying on top of the deck.
In accordance with the present broad invention there ls
provided a wind-resistant built up roof construction compLis.ing a
roof deck, a waterproof membrane overlying sa~d roof deck, a
plurality of insulating members overlying sald membrane and
comprising block~ of closed cell foam plastic resin materlal, a
plurality of paving blocks overlying and supported by said
insulating members in edge-to-edge relationship~ a plurality of
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6~93-4221
resilient members secured relative to said membrane and exkending
outwardly thereo~, a plurality of hold-down membexs each overlying
a plurality of said paving blocks and aligned with one of said
resilient members, and said resilient members including means
extending between adjacent paving blocks and intarconnecting each
hold-down member and a respective resilient member in order
resllien~ly to hold said pavin~ blocks in place for permitting
movement of the paving blocks under wind loads without substantial
movement of the waterproof membrane relative to said deck.
In particular, this invention preferably uses a spring
or other elastic means which is anchored -to the waterproofing
membrane by means maintalning the integrity of a waterproof
membrane overlying the deck. The spring or elastlc means extends
above foam plastic insulating slabs overlying the waterproof
membrane and is connected to a respective plate overlying the
junction of three or four lightweight concrete paving blocks.
When a wind tends to lift the paving blocks and/or the foam
plastic insulating slab, the spring or elastic means allows the
paving blocks and ~he Poam plas~ic insula~ing slab to rise a
limited extent, thus relievlng strains in the system. Upon
diminution or cessation of the wind, the springs or other elastic
elements return the paving blocks and insulating slabs ~o their
normal position. The foam insulating slabs and concrete paving
blocks can be separate, or they may be in~egral. For example,
extruded polystyrene foam with a nominal 3~8 inch thick facing oP
latex modified concrete mortar (see U.S.
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Patent 4,067,164) can be used inqtead of the separate
insulating slabs and paving blocks.
The present invention will best be understood
with reference to the ~ollowing speci~ication when
taken in connection with the accompanying drawings
wherein:
Figure 1 is a partial perspective view o~ a
roofing system constructed in accordance with the
pre~ent invention;
Figure 2 is a cross-3ectional view taken, for
example, substantially along the line 2-2 in Figure l;
Figure 3 i5 ,a perspective view of the parts
shown in Figure 2;
Figure 4 is a view similar to Figure 2 showing
the paving block~ a~ raised by a .wind;
Figure 5 is a view similar to Figure 1 showing
a modification o~ the invention;
Figure 6 is a cross sectional view taken
sub tantially along the line 6-6 in Figure 5;
Figure 7 is an enlarged view of the central
portion of Figure 6; and
Figure 8 is a view on a further enlarged scale
of a portion of Figure 7, but showing the paving blocks
a~ raised by the wind.
Turning now in greater partlcularity to the
drawings, and ~irst to Figures 1 to 4~ there wlll be
seen a built-up roof construction identified generally
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by the numeral 10. The roof construction includes a
roof deck 12 comprising a plurality of edge-to-edge
wood boards 14 supported by suitable joists or girders
(not shown). The roof deck 12 could equally well be o~
steel construction, or it could be concrete slab,
suitably supported. A waterproof membrane 16 lies on
and is qupported by the roof deck 12. This membrane
could be a built-up construction compri~ing sheet
material with asphalt or bitumin, or it could be a
single waterproof layer, such as of thermoplastic
material. An elastomeric material of a single
thicknes~ al~o is a possibility, and the membrane is so
illustrated.
Blooks or slabs of foam plastic insulation 18
lie on the membrane 16, and optionally may be cemented
thereto. Alternatively, the cement blocks and
in~ulation may be integral as roof insulation mentioned
earlier. The insulation preferably comprises foam
poly~tyrene plastic re~in. The concrete paving blocks
substantially abut one another in edge and end
relationship. The concrete paving blocks preferably
utilize a lightweight aggregate, and preferably are
reinforced by means such as continuous web or screen
me3h, or chopped strands of fibers, although plastic
such as polypropylene can be used. A fiber length of
- 1~4 in~h t~ 1 in~h i~ prefera~le. The co~cr~e
preferably i~ modified containing a latex, such as
3 styrene-butadiene latexl or an acrylic latex. Other
latexes could be used. The paving blocks preferably
are on the order of 1 inch thick and are on the order
of 3 ~eet by 6 Peet. The thickness of the foam
insulating panels depends on the degree of insulating
quantity de~ired, but typically would be on the order
of 1 to 6 inches. The polystyrene foam
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is of the closed cell variety for moisture resistance,
and the panels preferably are on the order oP 2 ~eet by
4 feet, although other~dimensions are contemplated.
The foam panels may simply be butted together, or may
be interconnected by a shiplap or tongue and groove
- construction.
The concrete blocks 20 may be laid ~o that the
junctions between blocks may be in the nature of four-
way Qrossovers. ~owever, prePerably adjacent blocksare oPPset longitudinally as shown in Figure 1 so that
the intersection~ among adjacent blocks are in the
nature of T-intersections. Each intersection is
covered by a thin steel plate which preferably is round
or rectangle in outline, and which is corrosion-
resistant, being galvanized, or stainless steel,
although other corro3ion-resistant metals or materials
may be qati~factory. As may be seen in Figures 2 to 4,
one end 24 of a spring 26, pre~erably a helical spring,
is secured to a respective disk or plate 22, such as by
welding. The spring also is corrosion-resistant, and
may be galvanized steel or stainless steel. The upper
end 24 of the spring Pit~ through an opening 28 between
block~ This apening may be formed by notching the
block~, or by qimply spacing the blocks slightly. The
spacing illustrated in Figures 2 and 4 is greater than
is actually ne~ ry~ a~d is P~r p~rp~se~ o~
illu~tration. Most of each spring 30 extends through a
3 vertical hole 30 through the foam plastic insulation
18, and this may be formed by slightly spacing adjacent
blocks oP insulation, but prePerably is a specially-
formed tubular hole through the insulation. The lower
end 3Z of each spring is formed by the terminating hook
349 and this hook fits over a crosspin 36 in an
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upwardly opening recess 38 in an upstanding boss 40
formed integrally with the membrane 160 The
undersurface of the foam plas~ic insulation may be
recessed at 42 to accommodate the boss. However, the
boss is somewhat exaggerated in size in the drawings
for purpo~es of illustration and the compressibility of
the elastomeric substance of the membrane and of the
foam plastic insulation may be enough to accommodate
without the neces~ity of providing a specific recess
42.
Normally the springs 26 and disk3 or plates 22
hold the concrete blocks 20 d~wn flat on top of the
foam insulation 18, and hold the insulation down tight
against the membrane 16. However, in the case of a
strong wind which might tend to raise and blow off the
blocks 20, the blocks may raise up against the forces
of the springs 26 as shown in Figure 4. The foam
insulating slabs 18 may also rise, although this is not
specifically illus~rated. This relieves ~tresses on
the roofing system, and upon diminution or subsiding of
the wind, the concrete blockq 20 will again be pulled
down on top of the foam plastic insulation slabs as
shown in Figures 1 and 2.
A modification of the invention is shown in
Figures 5 to 8. Many of the parts are the same as or
similar to those previously disclosed and are
identified by sl~ilar reference numerals with the
addition of the suffix a to avoid repetition of
de~cription. The distinction lies in the anchoring or
hold-down structure which uses an elastic material
rather than a metallic spring, and which uses a two
piece metal or plastic structure for anchoring to the
roof deck without disturbing the integrity of the
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membrane. Thus, as seen in Figures 6 to 8, the hold-
down structure comprises a hollow anchor block 44 o~
metal or plastic const~uction having a flat bottom wall
or floor 46 with a screw shank 48 secured to the bottom
thereof by suitable means such as welding or cementing
`~ for securing the box or body 44 to the boards 14a o~
the roof deck 12a. The body 44 further includes a ~lat
top wall 50 parallel to the bottom wall or floor 46,
and a serrated or pleated side wall 52. The side wall
52 may qimply consist of alternating hills and valleys,
but more preferably is arranged a~ a screw-threaded
ridge and valley. The membrane 16a is provided with an
up~tanding portion 54 fitting over the body 44. This
may be accomplished by using a heat-softenable pla~tic
resin for the membrane, or the membrane may be
manufactured with upstanding portions thereon. An
ela~tomeric rubber membrane such as ethylene-propyIene-
diene or butyl rubber will ~tretch over the hold-down
structure.
An outer shell 56 substantially conforms to the
exterior o~ the body or box 44 and comprises a flat top
wall 58 and a serrated or pleated side wall 60 having
alternating ridge~ and valleys. The outer shell 56
grips the upstanding portion 54 of the membrane 16a
about the body or box 44O Assembly is not difficult in
th~ ea~ o~ a s-c~th~a~d sid~ w~ll. If si~ply
alternating ribs and valleys are provided parallel to
3 one anotherl then either the ribs and valleys must not
be too deep, or the side wall must have vertical slots
to allow it to expand to ratchet over the body or
box 44.
A vertical tubular shank 62 extends between
confronting concrete blocks 20a. The thickness o~ the
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shank may require notching of the blocks, although they
may simply be spaced apart a bit farther than in the
first embodiment o~ the invention. The tubular shank
62 is made of an elastic material 9 preferably an
~lastomeric or rubber-like material which has an upper
generally circular ~lange integral with the shank and
bonded to the lower ~ace of a respective disk or plate
22a. Similarly, there is an integral lower ~lange 66
on the vertical tubular shank 52 which is bonded to the
upper face of the top wall 58 o~ the outer shell 56.
Norma~ly the parts are held in the position
shown in Figures ~ and 7 with the concrete blocks 20a
resting on top of the foam plastio insulation slabs
18a, and the latter lying on the upper surface of the
membrane 16a. In the case of a wind that might tend to
raise the concrete blocks 9 the~ vertical tubular shank
62 will stretch to allow the blocks to rise as shown in
Figure 8. The insulating slab may also rise, although
this is not specifically illustrated. Upon diminution
or ce~sation of the wind, the elasticity oY the
material of the vertical tubular shank 62 will again
return the parts to the position shown in Figures 6
and 7.
It will be observed that the modification of
the invention shown in Figures .5 to 8 has an added
advantage o~ anchoring the membrane 16a to the roo~
deck 12a without requiring adhesives~ this being
accomplished by the gripping of portions of the
membrane by the bodies 44 and outer shells 66 at spaced
locations.
In both embodiments of the invention
illustrated, the overlying disks or plates 22, 22a span
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joints of the concrete paving blocks to hold them down
resiliently by means of the corresponding spring or
elastic member. The concrete blocks are held down
without disturbing the integrity o~ the waterproof
diaphragm. The resulting roof construction is wind-
~ resistant in that the concrete paving blocks can rise
up against the resilient ~orce of the springs or
elastic members to relieve stresses in the roo~ing
system. The resilient anchoring structure promptly
restores the concrete paving blocks and the foamplastic insulation if necessary to rest position on the
rooY deok.
The specific examples of the invention a~
herein 3hown and described are for illustrative
purposes only. Various changes in structure will no
doubt occur to those skilled in the art and will be
understood as forming a part of the present invention
in~ofar as they fall within the spirit and soope of the
appended claims.
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