U.S. patent application number 12/205435 was filed with the patent office on 2009-07-30 for ballasted storm water retention system.
This patent application is currently assigned to CARLISLE INTANGIBLE COMPANY. Invention is credited to Michael J. DuCharme, Brandon M. Fuller.
Application Number | 20090188172 12/205435 |
Document ID | / |
Family ID | 40897797 |
Filed Date | 2009-07-30 |
United States Patent
Application |
20090188172 |
Kind Code |
A1 |
DuCharme; Michael J. ; et
al. |
July 30, 2009 |
BALLASTED STORM WATER RETENTION SYSTEM
Abstract
A roof system designed to retain water during storms and release
it slowly over a period of time includes a polymeric water
impervious membrane covered with a drainage board in turn covered
with a water retention mat. The water retention mat and drainage
board are held in position by ballast, preferably gravel. The mat
is designed to retain at least about 25% of a one-inch per hour
rainfall and release it gradually over 2 to 3 hours, thereby
reducing rain runoff during storms and reducing the load on a storm
sewer system
Inventors: |
DuCharme; Michael J.;
(Enola, PA) ; Fuller; Brandon M.; (Elliottsburg,
PA) |
Correspondence
Address: |
WOOD, HERRON & EVANS, LLP
2700 CAREW TOWER, 441 VINE STREET
CINCINNATI
OH
45202
US
|
Assignee: |
CARLISLE INTANGIBLE COMPANY
Syracuse
NY
|
Family ID: |
40897797 |
Appl. No.: |
12/205435 |
Filed: |
September 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61023257 |
Jan 24, 2008 |
|
|
|
Current U.S.
Class: |
52/11 |
Current CPC
Class: |
E04D 13/0477 20130101;
E04D 11/00 20130101 |
Class at
Publication: |
52/11 |
International
Class: |
E04D 13/00 20060101
E04D013/00 |
Claims
1. A roof system comprising in the following order: a roof deck; a
waterproof layer covering said roof deck; a drainage member
providing flow channels covering said waterproof layer; a moisture
retention mat supported by said drainage member; and ballast
covering said moisture retention mat.
2. The roof system claimed in claim 1 wherein said drainage member
comprises rigid spacers fixed to a water permeable layer.
3. The roof system claimed in claim 2 wherein said moisture
retention mat comprises a nonwoven polymeric mat.
4. The roof system claimed in claim 3 wherein said nonwoven
polymeric mat retains at least about 0.2 gallons of water per
square foot.
5. The roof system claimed in claim 2 wherein said ballast
comprises gravel.
6. The roof system claimed in claim 1 comprising an insulation
layer between said roof deck and said waterproof layer.
7. The roof system claimed in claim 1 further comprising a
protective mat between said drainage member and said waterproof
layer.
8. The roof system claimed in claim 3 wherein said waterproof layer
comprises a polymeric membrane.
9. A roof system wherein the outermost three layers consist of
ballast covering a water retention matting covering a water
drainage member.
10. A roof system comprising in the following order: a roof deck; a
waterproof layer covering said roof deck; a drainage member
providing water flow paths; a moisture retention mat supported by
said drainage member; and ballast covering said mat.
Description
RELATED APPLICATION
[0001] This application is related to and claims the benefit of
U.S. Provisional Patent Application Ser. No. 61/023,257, filed Jan.
24, 2008, the disclosure of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] Storm runoff presents a significant burden to sewage
systems. Excess water can exceed the capacity of the storm sewer
system. Drainage systems that include holding ponds can be used to
temporarily retain water and slowly feed this to sewer systems.
Such drainage systems can be relatively expensive, particularly as
their volume increases.
[0003] One way to reduce the storm runoff is to temporarily retain
water on a roof using a garden roof. The garden roof incorporates a
growth medium layer, which supports plant growth and also acts to
retain water. Thus, during a storm, the growth medium absorbs water
and gradually allows some of the water to run off the roof. This
slows the storm runoff, allowing the storm sewer system to handle
the water over a longer period of time.
[0004] Unfortunately, garden roofs are in many applications cost
prohibitive. Further, the maintenance costs of a garden roof must
also be considered.
SUMMARY OF THE INVENTION
[0005] The present invention is premised on the realization that
storm water runoff from a flat roof can be reduced utilizing a
ballasted storm water retention roof system. The storm water
retention roof system incorporates a water impervious roofing
membrane as the water barrier for the roof. This membrane may be
covered with a drainage board in turn covered with a water
retention mat. The drainage board and mat are held in position with
a ballast layer such as gravel.
[0006] The water retention mat holds a significant amount of water
from a storm, and releases this water over an extended period of
time. The water retention mat can be formed from various materials
such as nonwoven polymeric materials including recycled plastic.
The particular material selected, as well as the thickness of this
material, determine the amount of water retained, as well as the
retention period. Further, the drainage board prevents ponding of
water.
[0007] The objects and advantages of the present invention will be
further appreciated in light of the following detailed description
and drawings in which:
BRIEF DESCRIPTION OF THE DRAWING
[0008] FIG. 1 is a cross sectional view of a roof system according
to the present invention;
[0009] FIG. 2 is a perspective view partially broken away of the
water drainage board used in the present invention.
DETAILED DESCRIPTION
[0010] As shown in FIG. 1, the present invention is a roof
structure 10 that incorporates a roof deck 12 covered with a water
barrier layer 14. The roof structure 10 is a flat roof, meaning the
slope of the roof is less than about 1 inch per foot. Generally,
the slope is about 0.25 inch/foot. As shown, the water barrier
layer 14 is a polymeric membrane, although any water barrier layer
that is suitable for a flat roof surface can be used in the present
invention. Suitable polymeric membranes include EPDM, TPO and
polyvinylchloride. These are commonly used on flat roof surfaces.
The water barrier layer 14 can be installed in any typical manner.
For example, the membrane can be simply loose-laid, held with
mechanical fasteners, or fastened with an adhesive.
[0011] Between the roof deck 12 and the membrane 14 can be various
layers, as is well known. Typically, one may employ an insulation
layer 15 between the roof deck and the membrane.
[0012] Covering the membrane 14 is an optional, protective layer
17, which can be any layer that is typically employed as a
protective layer for a roof surface. These protective layers are
generally semi-rigid mats, and are typically the type employed for
a garden roof system. Typical protective layers can be formed from
tufted nonwoven polypropylene fibers. One such material is sold by
Carlisle Coating & Waterproofing, CCW 200 V, which is a thick,
nonwoven, cushioning fabric formed from polypropylene. Any stable
material which protects the membrane from the overlaid drainage
board can be used as necessary.
[0013] The protective layer 17 is, in turn, covered with a drainage
board or member 16. A drainage board simply provides water flow
channels above the membrane 14, which prevents ponding. This layer
may be excluded. Drainage board 16, in turn, is covered with a
water retention mat 18, which is, in turn, covered with ballast
20.
[0014] The drainage board 16, as shown, includes an upper mesh
layer 26 and a spacer layer 24. The spacer layer 24 is a solid
plastic member that has a series of truncated conical spacers 25. A
series of holes 22 in the upper surface 23 of the spacer layer 24
allows water flow from above drainage board 16 to channels 27. The
channels 27 within the layer between spacers 25 permit water flow.
This is shown in more detail in FIG. 2. The channels 27 in board 16
can provide a flow rate of 140-145 gpm/ft2 (ASTM D 4491).
[0015] The spacing and the height of the channels 27 are designed
to provide sufficient area for the desired water flow. Typically,
the spacers will provide about a 3/4-inch space between the upper
and lower surfaces. The upper layer 26, which is fixed to spacer
layer 24, supports the water retention mat 18 and allows water to
pass through to channels 27 from the retention mat 18. The upper
layer 26 can be any water pervious layer that is strong enough to
support the retention mat and gravel. This can be a nonwoven mat, a
woven mesh, or a perforated film.
[0016] One preferred drainage board is manufactured by Carlisle
Coating & Waterproofing, sold under the name CCW Miradrain
GR9200. This product is a high-performance retention composite with
a three-dimensional, high-impact polystyrene core, which forms the
layer 14 and the spacers 25. The upper layer includes holes 22,
which permit water flow. Generally, about 1501/8-inch holes every
square foot is acceptable. Another such product is CCW Miradrain HC
Drainage Board, which also has a similar structure.
[0017] These are one-piece drainage boards. The water flow channels
can also be provided using a variety of different structures, which
combine to form water drainage channels and support the water
retention mat 18 and gravel 20.
[0018] The water retention mat 18 is a porous mat, which is
designed to retain water during periods of heavy water flow. Water
retention mats are also referred to as water retention geotextiles.
Retention mats are typically used in garden roofs to provide a
water reservoir for plants. These mats act as sponges, holding
large quantities of water for use by the plants. The water
retention mats can be formed from fibers and can be woven or
nonwoven. The retention mat can also be formed from other porous
materials, such as open celled foams. The thickness of the water
retention mat is selected to retain the desired amount of
water.
[0019] There are a number of products on the market that will
function as water retention mats in the present invention such as
products sold by Huesker, Inc., HGTA-8-10-TTSPET,
HGTA-10-10-10-PET, CCW 200V, CCW 300V Protection Mat, and Carlisle
SynTec Moisture Retention Mat, as well as almost any
geotextile.
[0020] The moisture retention mat is designed to hold ten times its
weight in water and serve to slowly release the precipitation
through capillary action. It is formed from recycled fibers that
are held together in a tufted nonwoven web. It has a dry weight of
0.18 pounds per square foot, a water-saturated weight of 1.75
pounds per square foot, and holds approximately 0.2 gallons of
water per square foot.
[0021] Again, depending upon the desired water retention, one or
more layers of any particular water retention mat can be used to
achieve the desired water retention. The system should be designed
to retain at least 25% of the water from a one-inch per hour
rainfall, and release this over a period of three hours. However,
the system can be designed to retain less or more water, depending
upon the desired results.
[0022] The final course of the roof system is the ballast 20, which
holds the water drainage system, including the water retention mat
18 and the drainage board 16 and any protective layer 17 onto the
membrane surface. The ballast 20 can also be used to hold the
membrane 14 in position if the membrane 14 is not otherwise
fastened to the roof deck surface.
[0023] The ballast 20 is typically washed creek stone or gravel.
Other ballast would include paver stones, and the like. With
respect to the present invention, the term "ballast" specifically
excludes dirt or other growth medium used in a green roof surface.
Typically, gravel is employed for the ballast. The mass of the
ballast should be 10 to 24 lbs/ft.sup.2, generally about 17
lbs/ft.sup.2.
[0024] The roof structure of the present invention is constructed
using standard roof installation procedures to apply the water
impervious layer, such as the membrane and any insulation over the
roof deck. More specifically, the protective layer 17 is positioned
over membrane 14. The drainage board 16 is positioned over the
protective fabric with the spacers 25 facing upwardly, as shown.
The drainage boards 16 are not positioned within 12 inches from
curbs, parapets, drains, and other wall penetrations. The moisture
retention mats 18 are positioned over the drainage board 16 with
edges of adjacent moisture retention mats overlapped at least two
inches. If multiple layers of moisture retention mats are used, the
seams are staggered by, for example, twelve inches to prevent
gravel migration, and to increase retention capacity.
[0025] Rounded water-worn gravel is used as ballast and placed
directly over the moisture retention mat with a minimum of ten
pounds per square foot, depending on the wind load requirements.
Crushed stone is not advised for use as a ballast as the small
particles can clog the fabric.
[0026] Once installed, this roof system will help to control
rainwater runoff. In a heavy downpour, the rain will soak the
moisture retention mat 18. Once the mat is saturated, any
additional rainwater will immediately flow into channels 27 or over
the gravel surface. Once the rain has stopped, the water remaining
in mat 16 will slowly drip into channels 27 or simply
evaporate.
[0027] The roof system of the present invention provides several
advantages. In particular, it acts to retain water from a downpour
and release it slowly over an extended period of time. Further, it
accomplishes this without the significant added expense of a green
roof. Further, the structure of the present invention prevents
pooling of water, which would occur is one were simply to use a
water retention mat by itself, over a membrane roof.
[0028] This has been a description of the present invention along
with the preferred method of practicing the present invention.
However, the invention itself should only be defined by the
appended claims, WHEREIN WE CLAIM:
* * * * *