U.S. patent application number 12/107161 was filed with the patent office on 2008-12-25 for method for increasing wind uplift resistance of wood-framed roofs using closed-cell spray polyurethane foam.
Invention is credited to Richard S. Duncan.
Application Number | 20080313985 12/107161 |
Document ID | / |
Family ID | 40135051 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080313985 |
Kind Code |
A1 |
Duncan; Richard S. |
December 25, 2008 |
METHOD FOR INCREASING WIND UPLIFT RESISTANCE OF WOOD-FRAMED ROOFS
USING CLOSED-CELL SPRAY POLYURETHANE FOAM
Abstract
The invention provides a method and structural member for
securing a roof or an outer wall of a building against wind forces
tending to lift the roof or outer wall off the building. A
structural member has a panel, said panel comprising a plurality of
spaced apart beam members, and a sheathing having an inner side and
an outer side, the sheathing spanning a space between adjacent beam
members and being attached to the beam members such that the inner
side of the sheathing is in juxtaposition with the beam members. A
layer of a rigid, closed cell foam comprising a polymer adhesive
composition is on substantially the entirety of said beam members
and substantially the entirety of the inner side of the sheathing
such that the layer on the sheathing and the beam members is
substantially continuous, and adheres the sheathing to the beam
members.
Inventors: |
Duncan; Richard S.;
(Royersford, PA) |
Correspondence
Address: |
HONEYWELL INTERNATIONAL INC.
101 COLUMBIA ROAD, P O BOX 2245
MORRISTOWN
NJ
07962-2245
US
|
Family ID: |
40135051 |
Appl. No.: |
12/107161 |
Filed: |
April 22, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60945974 |
Jun 25, 2007 |
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60948269 |
Jul 6, 2007 |
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61036579 |
Mar 14, 2008 |
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Current U.S.
Class: |
52/309.1 ;
52/745.21 |
Current CPC
Class: |
E04B 7/22 20130101; E04D
13/1675 20130101; E04D 13/17 20130101; E04B 7/20 20130101 |
Class at
Publication: |
52/309.1 ;
52/745.21 |
International
Class: |
E04C 1/40 20060101
E04C001/40 |
Claims
1. A method of securing a roof or an outer wall of a building
against wind forces which comprises: a) providing a roof panel or
outer wall panel, said roof panel or outer wall panel comprising a
plurality of spaced apart beam members, and a sheathing having an
inner side and an outer side, the sheathing spanning a space
between adjacent beam members and being attached to the beam
members such that the inner side of the sheathing is in
juxtaposition with the beam members; and b) spraying a layer of a
foamable polymer adhesive composition onto at least a portion of
side walls of said beam members and substantially the entirety of
the inner side of the sheathing such that the layer on the
sheathing and the beam members is substantially continuous; c)
allowing the foamable polymer adhesive composition to form a rigid,
closed cell foam which adheres the sheathing to the beam
members.
2. The method of claim 1 wherein the foamable polymer adhesive
composition is a liquid.
3. The method of claim 1 wherein the beam members are attached to
the sheathing by nails, screws, clips, or combinations thereof.
4. The method of claim 1 wherein the beam members comprise wood,
wood composite, metal or combinations thereof.
5. The method of claim 1 wherein the sheathing comprises wood,
oriented strand board, fibrous cement, fiberglass reinforced
gypsum, expanded polystyrene, extruded polystyrene,
polyisocyanurate, foam board or combinations thereof.
6. The method of claim 1 wherein the adhesive composition comprises
a blowing agent comprising at least one of a hydrocarbon,
fluorocarbon, chlorocarbon, fluorochlorocarbon, halogenated
hydrocarbon, hydrofluoroolefin, hydrochlorofluoroolefin, CO.sub.2
generating material, or combinations thereof; and at least one of a
polyurethane, a polyisocyanurate, or a combination of a
polyurethane and a polyisocyanurate.
7. The method of claim 1 wherein the adhesive composition comprises
a blowing agent comprising water, organic acids that produce
CO.sub.2, hydrocarbons; ethers, halogenated ethers;
pentafluorobutane; pentafluoropropane; hexafluoropropane;
heptafluoropropane; trifluoropropene; tetrafluoropropene;
pentafluoropropene; chlorotrifluoropropene; trans1,2
dichloroethylene, methyl formate or combinations thereof; and at
least one of a polyurethane, a polyisocyanurate, or a combination
of a polyurethane and a polyisocyanurate.
8. The method of claim 1 wherein the adhesive composition comprises
a blowing agent comprising 1-chloro-1,2,2,2-tetrafluoroethane;
1,1-dichloro-1-fluoroethane; 1,1,1,2-tetrafluoroethane;
1,1,1,2-tetrafluoroethane; 1-chloro 1,1-difluoroethane;
1,1,1,3,3-pentafluorobutane; 1,1,1,2,3,3,3-heptafluoropropane;
trichlorofluoromethane, dichlorodifluoromethane;
1,1,1,3,3,3-hexafluoropropane; 1,1,1,2,3,3-hexafluoropropane;
difluoromethane; difluoroethane; 1,1,1,3,3-pentafluoropropane;
1,1,1,3-tetrafluoropropene; trans-1,1,1,3-tetrafluoropropene;
1,1,1,2-tetrafluoropropene; 1,1,1,2,3-pentafluoropropene;
1-chloro-3,3,3-trifluoropropene, or combinations thereof; and at
least one of a polyurethane, a polyisocyanurate, or a combination
of a polyurethane and a polyisocyanurate.
9. The method of claim 1 wherein the adhesive composition comprises
a blowing agent comprising 1,1,1,3,3-pentafluorobutane;
1,1,1,3,3-pentafluoropropane or combinations thereof; and at least
one of a polyurethane, a polyisocyanurate, or a combination of a
polyurethane and a polyisocyanurate.
10. The method of claim 1 wherein the adhesive composition
comprises a fluorine containing blowing agent, and a mixture of
ingredients that react to form at least one of a polyurethane or
polyisocyanurate foam, or a combination of a polyurethane and
polyisocyanurate foam, in the presence of the blowing agent.
11. The method of claim 1 wherein the rigid, closed cell foam is
present at a thickness of from about 2.5 cm. to about 15 cm.
12. A structural member for a roof or an outer wall of a building
comprising: a) a roof panel or outer wall panel, said roof panel or
outer wall panel comprising a plurality of spaced apart beam
members, and a sheathing having an inner side and an outer side,
the sheathing spanning a space between adjacent beam members and
being attached to the beam members such that the inner side of the
sheathing is in juxtaposition with the beam members; and b) a layer
of a rigid, closed cell foam comprising a polymer adhesive
composition on at least a portion of side walls of said beam
members and substantially the entirety of the inner side of the
sheathing such that the layer on the sheathing and the beam members
is substantially continuous, and adheres the sheathing to the beam
members.
13. The structural member of claim 12 wherein the beam members are
attached to the sheathing by nails, screws, clips, or combinations
thereof.
14. The structural member of claim 12 wherein the beam members
comprise wood, wood composite, metal or combinations thereof.
15. The structural member of claim 12 wherein the sheathing
comprises wood, oriented strand board, plywood, fibrous cement,
fiberglass reinforced gypsum, expanded polystyrene, extruded
polystyrene, polyisocyanurate, foam board or combinations
thereof.
16. The structural member of claim 12 wherein the rigid, closed
cell foam comprises a polyurethane, a polyisocyanurate, or
combinations thereof.
17. The structural member of claim 12 wherein the rigid, closed
cell foam is present at a thickness of from about 2.5 cm. to about
15 cm.
18. The structural member of claim 12 comprising a roof panel.
19. The structural member of claim 12 comprising an outer wall
panel
20. A structural member comprising: a) a panel, said panel
comprising a plurality of spaced apart beam members, and a
sheathing having an inner side and an outer side, the sheathing
spanning a space between adjacent beam members and being attached
to the beam members such that the inner side of the sheathing is in
juxtaposition with the beam members; and b) a layer of a rigid,
closed cell foam comprising a polymer adhesive composition on at
least a portion of side walls of said beam members and
substantially the entirety of the inner side of the sheathing such
that the layer on the sheathing and the beam members is
substantially continuous, and adheres the sheathing to the beam
members.
21. The structural member of claim 20 wherein the beam members are
attached to the sheathing by nails, screws, clips, or combinations
thereof.
22. The structural member of claim 20 wherein the beam members
comprise wood, wood composite or metal.
23. The structural member of claim 20 wherein the sheathing
comprises wood, oriented strand board, plywood, fibrous cement,
fiberglass reinforced gypsum, expanded polystyrene, extruded
polystyrene, polyisocyanurate, foam board or combinations
thereof.
24. The structural member of claim 20 wherein the rigid, closed
cell foam comprises a polyurethane, a polyisocyanurate, or
combinations thereof.
25. The structural member of claim 20 wherein the rigid, closed
cell foam is present at a thickness of from about 2.5 cm. to about
15 cm.
26. A structural member comprising: a) a panel, said panel
comprising a plurality of spaced apart beam members, and a
sheathing having an inner side and an outer side, the sheathing
spanning a space between adjacent beam members and being attached
to the beam members such that the inner side of the sheathing is in
juxtaposition with the beam members; b) an elongated channel for
the passage of ventilating air fixed on the inner side of the
sheathing between and separated from adjacent spaced apart beam
members, and b) a layer of a rigid, closed cell foam comprising a
polymer adhesive composition on at least a portion of side walls of
said beam members, on the elongated channel, and substantially the
entirety of on the inner side of the sheathing between the
elongated channel and the spaced apart beam members, such that the
layer of rigid, closed cell foam on the sheathing, the elongated
channel and the beam members is substantially continuous, and
adheres the sheathing to the beam members.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
patent applications 60/945,974 filed Jun. 25, 2007; and 60/948,269
filed on Jul. 6, 2007; and 61/036,579 filed Mar. 14, 2008, which
are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method and structural
member for securing a roof or an outer wall of a building against
wind forces tending to lift the roof or outer side wall off the
building.
[0004] 2. Description of the Related Art
[0005] It is well known that high wind forces from storms and
hurricanes exert significant uplift forces and tend to lift roofs
and remove side walls from a building structure. Wood, wood
composite, or equivalent structures predominate in residential
construction, and when wood framing is employed the structure must
be protected from forces developed by high winds. Houses in the
Caribbean or southeast coastal regions of the United States are
situated in the pathway of annual hurricanes and as such, encounter
hurricanes and/or tornadoes from time to time. Such houses in the
Caribbean area are typically constructed of cement blocks with a
wooden top plate fastened to the top of cement block walls, for
attaching a side walls and a wooden roof. In the case of upward
loads, the roof is generally tied to the walls using a variety of
steel connectors that connect the top plate to the walls. Due to
house locations in a susceptible high wind area, some building
codes require that houses built with wooden roof support beams have
a hurricane ties in place on every rafter. The installation of such
ties slows the foundation and framing stages of construction, which
in turn increases labor costs. From the foregoing, it is apparent
that there is a need for a strong side wall and roof tie system
that provides for uplift loads which is cost effective and easy to
install.
[0006] The primary failure locations on buildings during hurricanes
are at the roof to wall connection, or at the wall to floor
connection. Decks of sloped roofs in residential buildings are
particularly vulnerable to damage caused by wind uplift. When a
roof is removed in a storm, rain enters the building, often
resulting in a total loss of the building and its contents. The
causes of wind uplift damage to roof decks can be from improper
nailing techniques, wrong nails, wrong nail spacing, or poor
workmanship when nails miss the structural members below or by use
of an overdriven fastener. There are existing means to remediate
this problem. During roof replacement, fasteners can be added. In
lieu of roof replacement, adhesive caulks can be used on the attic
side to improve the attachment bond strength between the roof deck
and the structural members. U.S. Pat. No. 6,931,813 provides a
roof-tie bracket system for bracing a wood framed roof of a
building. The structure is reinforced against the destructive wind
forces by high strength brackets attached to every rafter where it
joins the ceiling plates. The roof-tie bracket is connected to the
structure by way of a plurality of fasteners, such as nails or lag
bolts. U.S. Pat. No. 6,725,623 provides a method for controlling
uplift on a roof with a plurality of clamps and transverse bars.
The transverse bars have a series of downward extending brackets
each of which has a flexible foot to press down on the flat panels
of the roof, thereby providing a structural brace to hold the
panels down in a heavy wind. U.S. Pat. No. 6,427,392 provides a
method of roof reinforcement against hurricanes by placing an
anchor assembly into a cavity in a wall and securing the anchor
assembly to wall coverings enclosing the cavity around an anchorage
area and then tying the anchor assembly to the roof structure.
These are all point to point mechanical anchoring systems. U.S.
Pat. No. 5,890,327 teaches a method of reinforcing or retrofitting
building roof structures against hurricane force winds by applying
a thin stream of a liquid polymer foam adhesive under pressure
upwardly along the intersections of the rafters or support members
and the roof panels to provide a filleted connection. The liquid
polymer foam adhesive is only effective in corner regions formed at
the intersections between said support members and interior
surfaces of the roof panels.
[0007] The present invention provides a solution to the above and
other problems by providing improved reinforcing and anchoring of a
roof and side walls to a building structure, wherein a greater hold
down force is applied to the roof and side walls to counter the
uplift and horizontal forces generated by high winds.
[0008] This has been accomplished according to this invention by
providing a roof panel or outer wall panel, comprising spaced apart
beam members, and a sheathing attached to and spanning a space
between adjacent beam members; and spraying and adhering a layer of
a foamable polymer adhesive composition such as a polyurethane or
polyisocyanurate adhesive composition, which foamable polymer
adhesive composition is preferably present in the form of foamable
liquid, onto substantially the entirety of the beam members and
substantially the entirety of the inner side of the sheathing such
that the layer on the sheathing and the beam members is preferably
substantially continuous. By substantially continuous it is meant
that there are substantially no breaks or spaces in the layer,
across the area on which it is deposited. A closed cell spray
polyurethane or polyisocyanurate foam is applied at a uniform depth
under a roof deck or side wall sheathing between the structural
beams to provide additional bonding strength. This is different
from filleted adhesive caulks in that it provides additional
bonding strength and also significant insulation under the roof
deck or side walls. This creates a conditioned attic or side wall
space and seals soffit areas to deter the intrusion of wind driven
rain. This also provides a significant energy savings.
[0009] This invention uses such improved roof and side wall panels
to help secure the roof to the side walls and the side walls to the
flooring, and stiffens the roof and side walls to distribute wind
loads to the roof and side wall framing. The present invention can
be incorporated during initial construction of a structure, or may
be retrofitted into existing structures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of a structural test panel
comprising an array of five parallel 2''.times.4'' by 72''
spruce-pine-fir dimensional lumber spaced on 24'' centers. Then a
7/16'' oriented strand board (OSB) sheet is attached by nails.
[0011] FIG. 2 is a side view of the structural test panel of FIG.
1
[0012] FIG. 3 is a side view of the structural test panel of FIG. 2
having a filleted application, 3'' high, 5-6'' wide of a
polyurethane closed-cell spray foam.
[0013] FIG. 4 is a side view of the structural test panel of FIG. 2
having a full layer application, 3'' thick of a polyurethane
closed-cell spray foam.
[0014] FIG. 5 shows a prior art arrangement where attic baffles are
used along a roof panel where fibrous insulation is placed between
structural members and in contact with the attic baffle.
[0015] FIG. 6 shows a view of the inventive closed-cell spray foam
with an attic baffle placed between structural members and the foam
is in contact with the attic baffle.
DESCRIPTION OF THE INVENTION
[0016] The invention provides a method of securing a roof or an
outer wall of a building against wind forces, which comprises:
[0017] a) providing a roof panel or outer wall panel, said roof
panel or outer wall panel comprising a plurality of spaced apart
beam members, and a sheathing having an inner side and an outer
side, the sheathing spanning a space between adjacent beam members
and being attached to the beam members such that the inner side of
the sheathing is in juxtaposition with the beam members; and [0018]
b) spraying a layer of a foamable polymer adhesive composition onto
at least a portion of side walls of said beam members and
substantially the entirety of the inner side of the sheathing such
that the layer on the sheathing and the beam members is
substantially continuous; [0019] c) allowing the foamable polymer
adhesive composition to form a rigid, closed cell foam which
adheres the sheathing to the beam members.
[0020] The invention also provides a structural member for a roof
or an outer wall of a building comprising:
a) a roof panel or outer wall panel, said roof panel or outer wall
panel comprising a plurality of spaced apart beam members, and a
sheathing having an inner side and an outer side, the sheathing
spanning a space between adjacent beam members and being attached
to the beam members such that the inner side of the sheathing is in
juxtaposition with the beam members; and b) a layer of a rigid,
closed cell foam comprising a polymer adhesive composition on at
least a portion of side walls of said beam members and
substantially the entirety of the inner side of the sheathing such
that the layer on the sheathing and the beam members is
substantially continuous, and adheres the sheathing to the beam
members.
[0021] The invention further provides a structural member
comprising: [0022] a) a panel, said panel comprising a plurality of
spaced apart beam members, and a sheathing having an inner side and
an outer side, the sheathing spanning a space between adjacent beam
members and being attached to the beam members such that the inner
side of the sheathing is in juxtaposition with the beam members;
and [0023] b) a layer of a rigid, closed cell foam comprising a
polymer adhesive composition on at least a portion of side walls of
said beam members and substantially the entirety of the inner side
of the sheathing such that the layer on the sheathing and the beam
members is substantially continuous, and adheres the sheathing to
the beam members.
[0024] The invention still further provides a structural member
comprising: [0025] a) a panel, said panel comprising a plurality of
spaced apart beam members, and a sheathing having an inner side and
an outer side, the sheathing spanning a space between adjacent beam
members and being attached to the beam members such that the inner
side of the sheathing is in juxtaposition with the beam members;
[0026] b) an elongated channel for the passage of ventilating air
fixed on the inner side of the sheathing between and separated from
adjacent spaced apart beam members, and [0027] b) a layer of a
rigid, closed cell foam comprising a polymer adhesive composition
on at least a portion of side walls of said beam members, on the
elongated channel, and substantially the entirety of on the inner
side of the sheathing between the elongated channel and the spaced
apart beam members, such that the layer of rigid, closed cell foam
on the sheathing, the elongated channel and the beam members is
substantially continuous, and adheres the sheathing to the beam
members.
[0028] Roofs and side walls in residential and light commercial
buildings comprise two main elements: beams such as wood, wood
composite, metal or combinations thereof as framing and rafters,
and a sheathing. A sheathing is a layer of boards or of other wood
or fiber materials applied to the outer studs, joist, and rafters
of a building to strengthen the structure and serve as a base for
an exterior weatherproof cladding. Sheathing is typically plywood,
oriented strand board (OSB) fibrous cement, fiberglass reinforced
gypsum, insulated sheathings, such as expanded and extruded
polystyrene, or polyisocyanurate, but can also be foam board and
combinations of these materials. Beams are typically dimensional
lumber made from softwood species of wood, engineered woods or
formed steel. These have nominal cross sections of 2''.times.3'',
2''.times.4'', 2''.times.6'', 2''.times.8'', 2''.times.10'' or
2''.times.12''. These beams can be built as prefabricated truss
assemblies or site-built as rafters or side framing. Sloped
residential roofs and side walls are constructed by spacing the
beams at regular intervals, typically 12'', 16'' or 24'', most
commonly 24''. Sheathing is typically available in 4 ft..times.8
ft. sheets and is placed and fastened to a face of the beam with
such fasteners as nails, screws or clips. Application of these
fasteners is not always done properly in both new and existing
homes, and can be a main cause of roof or side wall failure.
Roofing materials, including underlayment and shingles are then
attached to the outside surface of the sheathing.
[0029] According to this invention, a uniform thickness of a closed
cell spray polyurethane or polyisocyanurate foam adhesive
insulation (ccSPF) is then applied on the underside of the roof
deck or side wall sheathing and maintains a continuous contact with
at least a portion of the two opposite sides of the sides of the
beams, preferably at least half of the width of the two opposite
sides of the sides of the beams, and more preferably substantially
the entirety of the two opposite sides of the beams which are
perpendicular to the sheathing. The closed cell spray polyurethane
or polyisocyanurate foam adhesive, because of its inherent strength
and stiffness, and its ability to form a tenacious bond to other
construction materials such as wood and steel, acts as an adhesive.
The closed cell spray polyurethane or polyisocyanurate foam
adhesive acts to uniformly distribute the wind load from the
sheathing to the beams, thus increasing the uplift load
considerably. Testing has shown that typical uplift loads increase
from approximately 70 pounds per square foot to approximately
240-285 pounds per square foot after the application of about 3''
thickness of a closed cell spray polyurethane or polyisocyanurate
foam adhesive. Considering that roofs of homes in coastal hurricane
areas can be subjected to wind uplift loads of from about 100 to
about 130 psf, this increase is significant. In addition to
providing uplift resistance, an application of about 3'' thickness
of a closed cell spray polyurethane or polyisocyanurate foam
adhesive can provide additional insulation, on the order of R19.
Since closed cell spray polyurethane or polyisocyanurate foam
adhesive is water resistant, it can also be used to strengthen
soffit areas against wind damage and prevent intrusion of wind
driven rain in these areas. Closed cell spray polyurethane or
polyisocyanurate foam adhesive may also provide a measure of
corrosion protection to mechanical fasteners and brackets in roof
structures.
[0030] Closed cell spray polyurethane or polyisocyanurate foam
adhesives are well known in the art and are generally commercially
available. In general, polyurethane or polyisocyanurate foams are
prepared by combining an isocyanate, a polyol or mixture of
polyols, a blowing agent or mixture of blowing agents, and other
materials such as catalysts, surfactants, and optionally, flame
retardants, colorants, or other additives. Methods of producing
polyurethane and polyisocyanurate foams are generally known and
consist in general of the reaction of an organic polyisocyanate
(including diisocyanate) and a polyol or mixture of polyols in the
presence of a volatile blowing agent, which is caused to vaporize
by the heat liberated during the reaction of isocyanate and polyol.
This reaction can be enhanced through the use of amine and/or other
catalysts as well as surfactants. The catalysts ensure adequate
curing of the foam, while the surfactants regulate and control cell
size. Flame-retardants are traditionally added to rigid
polyurethane or polyisocyanurate foam to reduce its flammability.
Fluorocarbons act not only as blowing agents by virtue of their
volatility, but also are encapsulated or entrained in the closed
cell structure of the rigid foam and are the major contributor to
the low thermal conductivity properties of rigid polyurethane
foams. The use of a fluorocarbon as the preferred commercial
expansion or blowing agent in insulating foam applications is based
in part on the reduced thermal conductivity, or k-factor associated
with the foam produced. K-factor is defined as the rate of transfer
of heat energy by conduction through one square foot of one inch
thick homogenous material in one hour where there is a difference
of one degree Fahrenheit perpendicularly across the two surfaces of
the material. Since the utility of closed-cell polyurethane-type
foams is based, in part, upon their thermal insulation properties,
it would be advantageous to identify materials that produce lower
k-factor foams. It is convenient in many applications to provide
the components for polyurethane or polyisocyanurate foams in
pre-blended foam formulations. Most typically, the foam formulation
is pre-blended into two components. The isocyanate or
polyisocyanate composition comprises the first component, commonly
referred to as the "A" component. The polyol or polyol mixture,
surfactant, catalysts, blowing agents, flame retardant, and other
isocyanate reactive components comprise the second component,
commonly referred to as the "B" component. While the surfactant,
catalyst(s) and blowing agent are usually placed on the polyol
side, they may be placed on either side, or partly on one side and
partly on the other side. Accordingly, polyurethane or
polyisocyanurate foams are readily prepared by bringing together
the A and B side components for spray applied foams, froths, and
the like. Optionally, other ingredients such as fire retardant,
colorants, auxiliary blowing agents, water, and even other polyols
can be added as a third stream to the mix head or reaction site.
Most conveniently, however, they are all incorporated into one B
component. The foam is a preferably applied at a thickness of from
about 2.5 cm to about 15 cm. The foam may be applied as single or
multiple layers.
[0031] Any organic polyisocyanate can be employed in polyurethane
or polyisocyanurate foam synthesis inclusive of aliphatic and
aromatic polyisocyanates. Preferred, as a class is the aromatic
polyisocyanates. Preferred polyisocyanates for rigid polyurethane
or polyisocyanurate foam synthesis are the polymethylene polyphenyl
isocyanates, particularly the mixtures containing from about 30 to
about 85 percent by weight of methylenebis(phenyl isocyanate) with
the remainder of the mixture comprising the polymethylene
polyphenyl polyisocyanates of functionality higher than 2.
Preferred polyisocyanates for flexible polyurethane foam synthesis
are toluene diisocyanates including, without limitation,
2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and mixtures
thereof.
[0032] Typical polyols used in the manufacture of rigid
polyurethane foams include, but are not limited to, aromatic
amino-based polyether polyols such as those based on mixtures of
2,4- and 2,6-toluenediamine condensed with ethylene oxide and/or
propylene oxide. Another example is aromatic alkylamino-based
polyether polyols such as those based on ethoxylated and/or
propoxylated aminoethylated nonylphenol derivatives. These polyols
are generally preferred in spray applied polyurethane foams.
Another example is sucrose-based polyols such as those based on
sucrose derivatives and/or mixtures of sucrose and glycerine
derivatives condensed with ethylene oxide and/or propylene
oxide.
[0033] Typical polyols used in the manufacture of flexible
polyurethane foams include, but are not limited to, those based on
glycerol, ethylene glycol, trimethylolpropane, ethylene diamine,
pentaerythritol, and the like condensed with ethylene oxide,
propylene oxide, butylene oxide, and the like. These are generally
referred to as "polyether polyols". Another example is the graft
copolymer polyols, which include, but are not limited to,
conventional polyether polyols with vinyl polymer grafted to the
polyether polyol chain. Yet another example is polyurea modified
polyols which consist of conventional polyether polyols with
polyurea particles dispersed in the polyol.
[0034] Examples of polyols used in polyurethane modified
polyisocyanurate foams include, but are not limited to, aromatic
polyester polyols such as those based on complex mixtures of
phthalate-type or terephthalate-type esters formed from polyols
such as ethylene glycol, diethylene glycol, or propylene glycol.
These polyols may be blended with other types of polyols such as
sucrose-based polyols, and used in polyurethane foam
applications.
[0035] Catalysts used in the manufacture of polyurethane foams are
typically tertiary amines including, but not limited to,
N-alkylmorpholines, N-alkylalkanolamines,
N,N-dialkylcyclohexylamines, and alkylamines where the alkyl groups
are methyl, ethyl, propyl, butyl and the like and isomeric forms
thereof, as well as heterocyclic amines. Typical, but not limiting,
examples are triethylenediamine, tetramethylethylenediamine,
bis(2-dimethylaminoethyl)ether, triethylamine, tripropylamine,
tributylamine, triamylamine, pyridine, quinoline,
dimethylpiperazine, piperazine, N,N-dimethylcyclohexylamine,
N-ethylmorpholine, 2-methylpiperazine, N,N-dimethylethanolamine,
tetramethylpropanediamine, methyltriethylenediamine, and mixtures
thereof.
[0036] Optionally, non-amine polyurethane catalysts are used.
Typical of such catalysts are organometallic compounds of lead,
tin, titanium, antimony, cobalt, aluminum, mercury, zinc, nickel,
copper, manganese, zirconium, and mixtures thereof. Exemplary
catalysts include, without limitation, lead 2-ethylhexoate, lead
benzoate, ferric chloride, antimony trichloride, and antimony
glycolate. A preferred organo-tin class includes the stannous salts
of carboxylic acids such as stannous octoate, stannous
2-ethylhexoate, stannous laurate, and the like, as well as dialkyl
tin salts of carboxylic acids such as dibutyl tin diacetate,
dibutyl tin dilaurate, dioctyl tin diacetate, and the like.
[0037] In the preparation of polyisocyanurate foams, trimerization
catalysts are used for the purpose of converting the blends in
conjunction with excess A component to
polyisocyanurate-polyurethane foams. The trimerization catalysts
employed can be any catalyst known to one skilled in the art
including, but not limited to, glycine salts and tertiary amine
trimerization catalysts, alkali metal carboxylic acid salts, and
mixtures thereof. Preferred species within the classes are
potassium acetate, potassium octoate, and
N-(2-hydroxy-5-nonylphenol)methyl-N-methylglycinate.
[0038] Dispersing agents, cell stabilizers, and surfactants may be
incorporated into the blowing agent mixture. Surfactants, better
known as silicone oils, are added to serve as cell stabilizers.
Some representative materials are sold under the names of DC-193,
B-8404, and L-5340 which are, generally, polysiloxane
polyoxyalkylene block copolymers such as those disclosed in U.S.
Pat. Nos. 2,834,748, 2,917,480, and 2,846,458.
[0039] Other optional additives for the blowing agent mixture may
include flame retardants such as tris(2-chloroethyl) phosphate,
tris(2-chloropropyl) phosphate, tris(2,3-dibromopropyl) phosphate,
tris(1,3-dichloropropyl) phosphate, diammonium phosphate, various
halogenated aromatic compounds, antimony oxide, aluminum
trihydrate, polyvinyl chloride, and the like. Other optional
ingredients may include from 0 to about 5 percent of water based on
the weight of the polyol blend, which chemically reacts with the
isocyanate to produce carbon dioxide. The carbon dioxide acts as an
auxiliary-blowing agent.
[0040] Also included in the mixture are blowing agents. Generally
speaking, the amount of blowing agent present in the blended
mixture is dictated by the desired foam densities of the final
polyurethane or polyisocyanurate foams products. The polyurethane
foams produced can vary in density from about 1.0 to about 6.0
pounds per cubic foot, more preferably from about 1.8 to about 4.0
pounds per cubic foot and most preferably 2 to 4 pound per cubic
foot. The density obtained is a function of how much of the blowing
agent, or blowing agent mixture, is present in the A and/or B
components, or that is added at the time the foam is prepared.
[0041] When spray foam is applied, the A-side chemicals (e.g.
polyisocyanate) and B-side chemicals are mixed in appropriate
amounts, typically equal amounts by volume, and then atomized into
a mist. The B-side contains polyols, the blowing agents, catalysts,
fire retardants, etc. The blowing agent is in a liquid form in
solution in the B-side. In the case of water as blowing agent, the
water mixes with the polyisocyanate to form CO.sub.2 gas, it
creates gas cells in the polyurethane. The component parts are
mixed in the spray gun. The polyurethane is created as the two
chemicals mix and hits the wall or roof surface.
[0042] Useful blowing agents non-exclusively include: hydrocarbons,
methyl formate, halogen containing compounds, especially fluorine
containing compounds and chlorine containing compounds such as
halocarbons, fluorocarbons, chlorocarbons, fluorochlorocarbons,
halogenated hydrocarbons such as hydrofluorocarbons,
hydrochlorocarbons, hydrofluorochlorocarbons, hydrofluoroolefins,
hydrochlorofluoroolefins, CO.sub.2 generating materials such as
water, and organic acids that produce CO.sub.2 such as formic acid.
Examples non-exclusively include low-boiling, aliphatic
hydrocarbons such as ethane, propane and butane, normal pentane,
isopentane and cyclopentane; ethers and halogenated ethers; trans
1,2-dichloroethylene, pentafluorobutane; pentafluoropropane;
hexafluoropropane; and heptafluoropropane;
1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124); and
1,1-dichloro-1-fluoroethane (HCFC-141b) as well as
1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1,2-tetrafluoroethane
(HFC-134a); 1-chloro 1,1-difluoroethane (HCFC-142b);
1,1,1,3,3-pentafluorobutane (HFC-365mfc);
1,1,1,2,3,3,3-heptafluoropropane (HCF-227ea);
trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12);
1,1,1,3,3,3-hexafluoropropane (HFC-236fa);
1,1,1,2,3,3-hexafluoropropane (HFC-236ea); difluoromethane
(HFC-32); difluoroethane (HFC-152a); 1,1,1,3,3-pentafluoropropane
(HFC-245fa); trifluoropropenes, pentafluoropropenes,
chlorotrifluoropropenes, tetrafluoropropenes including
1,1,1,3-tetrafluoropropene (HFO-1234ze),
trans-1,1,1,3-tetrafluoropropene (trans-HFO-1234ze),
1,1,1,2-tetrafluoropropene (HFO-1234yf),
1,1,1,2,3-pentafluoropropene (HFO-1225ye),
1-chloro-3,3,3-trifluoropropene (HCFC-1233zd), and low-global
warming hydrofluorocarbons such as hydrofluoroolefins and
hydrofluoroethers. Combinations of any of the aforementioned
blowing agents are useful.
[0043] The most preferred blowing agent is
1,1,1,3,3-pentafluoropropane (HFC-245fa) which is commercially
available from Honeywell International Inc. as Enovate Blowing
Agent. This latter molecule remains in solution until the heat
generated by the polyurethane and/or the polyisocyanurate reaction
vaporizes it and creates the gas in the cells of the polyurethane
foam.
[0044] In one embodiment, the mixture comprises only one blowing
agent. In another embodiment the mixture comprises a plurality of
blowing agents, for example a combination of two blowing agents or
combinations of three blowing agents. When combinations of two or
more blowing agents are employed, each individual blowing agent may
be present in an amount of from about 1 percent by weight to about
99 percent by weight, wherein the total amount of blowing agent is
100% by weight. In a two component combination of blowing agents,
one blowing agent may be present in an amount of from about 1
percent by weight to about 50 percent by weight and the other
blowing agent may be present in an amount of from about 50 percent
by weight top about 99 percent by weight.
[0045] One useful combination of blowing agents comprises
1,1,1,3,3-pentafluorobutane and at least one fluorinated
hydrocarbon selected from the group consisting of
1,1,1,2-tetrafluoroethane, 1,1,1,3,3-pentafluoropropane,
1,1,1,3,3,3-hexafluoropropane and 1,1,1,2,3,3,3-heptafluoropropane.
A particularly useful combination of blowing agents comprises from
about 50% to about 99% by weight of 1,1,1,3,3-pentafluorobutane and
from about 1% to 50% by weight of at least one fluorinated
hydrocarbon selected from the group consisting of
1,1,1,2-tetrafluoroethane, 1,1,1,3,3-pentafluoropropane,
1,1,1,3,3,3-hexafluoropropane and
1,1,1,2,3,3,3-heptafluoropropane.
[0046] Another useful combination of blowing agents comprises a)
pentafluorobutane, and b) at least one further blowing agent
selected from the group consisting of low-boiling, aliphatic
hydrocarbons selected from the group consisting of ethane, propane
and butane, normal pentane, isopentane, or cyclopentane;
halogenated hydrocarbons; ethers and halogenated ethers;
difluoromethane (HFC-32); difluoroethane; 1,1,2,2-tetrafluoroethane
(HFC-134); 1,1,1,2-tetrafluoroethane (HFC-134a);
pentafluoropropane; hexafluoropropane, and heptafluoropropane;
particularly wherein the pentafluorobutane is
1,1,1,3,3-pentafluorobutane (HFC-365mfc), and the further blowing
agent comprises at least one of 1,1-difluoroethane (HFC-152a),
1,1,1,3,3-pentafluoropropane (HFC-245fa),
1,1,2,3,3,3-hexafluoropropane (HFC-236ea),
1,1,1,3,3,3-hexafluoropropane (HFC-236fa) or
1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). This is useful when
comprising 10 to 70% by weight of HFC-365mfc and 90 to 30% by
weight of the further blowing agent, and optionally further
comprises 2 to 50% by weight of carbon dioxide.
[0047] Another useful combination of blowing agents comprises
1,1,1,3,3-pentafluorobutane (HFC-365mfc) and
1,1,1,3,3-pentafluoropropane (HFC-245fa). Useful amounts may range
from up to about 50 weight percent of HFC-365mfc and about 50
weight percent or more of HFC-245fa.
[0048] Another useful combination of blowing agents comprises
1,1,1,3,3-pentafluorobutane (HFC-365mfc) and
1,1,1,3,3-pentafluoropropane (HFC-245fa). Useful amounts may have
an HFC-365mfc to HFC-245fa weight ratio range of from 40:60 to
about 80:20.
[0049] Another useful combination of blowing agents comprises
HFC-365mfc, HFC-227ea and one or both of HFC-245fa and HFC-134a.
Preferably 65 to 85 parts by weight comprises HFC-365mfc and
HFC-227ea of which percentage, 80 to 95 parts by weight are
HFC-365mfc, and the remainder is HFC-227ea; and at least 15 parts
by weight comprises one or both of HFC-245fa and HFC-134a.
[0050] The blowing agent compositions according to the invention
may include other optional ingredients such as phosphorus compounds
and catalysts.
[0051] A useful combination comprises from about 10 to about 20% by
weight of a phosphorus compound, preferably triethyl phosphate or
tris-chloroisopropyl phosphate; and a mixture of: a) HFC-365mfc,
and b) HFC-134a, HFC-227ea or HFC-245fa.
[0052] A useful combination comprises HFC-365mfc and a catalyst
which catalyses the polyol/isocyanate reaction and, optionally
which catalyses the trimerization of isocyanates.
[0053] Closed-cell spray foams suitable for this application
preferably have the following nominal properties:
TABLE-US-00001 Property ASTM Test Unit Value Nominal Density:
D-1622 lbs/ft.sup.3 1.5-4.0 Sprayed-in-Place R Value at 75.degree.
F. C-518 R/inch 5.0-8.0 mean temperature, measured 6 months after
foam manufacture Compressive D-1621 Psi 20-60 Strength: Parallel to
Rise Tensile Strength D-1623 Psi 30-100 Closed Cell Content D-2856
% >80
[0054] Useful closed-cell spray foams are disclosed in U.S. Pat.
Nos. 6,414,046; 7,214,294; 6,843,934, 6,806,247, 6,790,820;
6,784,150, among others, and which are incorporated herein by
reference.
[0055] Useful closed-cell spray foams include Comfort Foam.RTM.
FE178, FE158, CF178, CF158 commercially available from BASF
Polyurethanes--Foam Enterprises (a division of BASF) of Florham
Park, N.J.; BaySeal.TM. 2.0 commercially available from BaySystems
(a division of Bayer) of Spring, Tex.; Corbond.RTM. commercially
available from Corbond of Bozeman, Mont.; HeatLok Soy 0240
commercially available from Demilec USA of Arlington, Tex.;
Styrofoam.TM. 2.0 commercially available from Dow Chemical Company
of Midland, Mich.; PF-173, PF-193 commercially available from Gaco
Western of Seattle, Wash.; Permax commercially available from Resin
Technology Division (a division of Henry Co.) of Ontario, CA; Foam
Lok.TM. FL-2000.TM. commercially available from Lapolla Coatings of
Houston, Tex.; InsulStar.RTM. commercially available from NCFI
Polyurethanes (formerly North Carolina Foam Industries) of Mt.
Airy, N.C.; and DuraFoam-Duraseal.TM. 1.9 commercially available
from Urethane Contractor Supply Company of Phoenix, Ariz.
[0056] In another embodiment of the invention, an elongated channel
for the passage of ventilating air is fixed on the inner side of
the sheathing between and separated from adjacent spaced apart beam
members. In this case, a layer of the rigid, closed cell foam
polymer adhesive composition is positioned on the side walls of the
beam members, on the elongated channel, and on the inner side of
the sheathing between the elongated channel and the spaced apart
beam members. The layer of rigid, closed cell foam on the
sheathing, the elongated channel and the beam members is
substantially continuous, and adheres the sheathing to the beam
members. As stated above, by substantially continuous it is meant
that there are substantially no breaks or spaces in the layer,
across the area on which it is deposited.
[0057] Some building product manufacturers, most notably certain
asphalt shingle manufactures, require proper attic ventilation to
avoid heat damage to the shingles. The generally accepted rule is
to provide 1 ft.sup.2 of ventilation opening for every 300 ft.sup.2
of attic space. Many house designs employ cathedralized ceilings,
where insulation is applied between the structural members in the
vicinity of the roof deck. To achieve proper ventilation in this
application, attic baffles are used along the entire when applying
insulation under a roof deck in a conditioned attic or
cathedralized ceiling. FIG. 5 shows a prior art arrangement where
fibrous insulation is then placed between the structural members
and in direct contact with a double channel baffle.
[0058] FIG. 6 shows an arrangement according to the invention where
an attic baffle is provided with a closed-cell spray foam to
provide the requisite ventilation needed and provide adequate wind
uplift resistance. In one embodiment, a typical double channel
baffle as shown in FIG. 5 can be split into a single chute as shown
in FIG. 6, and installed along a central axis of the sheathing
parallel to the structural members. This would allow sufficient
contact area between stapling flanges of the single chute baffle
and the structural members needed for the spray foam to adhere
between the roof deck and the sidewall of the structural member.
This design can provide a 1:300 ventilation area as is required in
almost all home designs. In addition, the application of
closed-cell spray foam may trap water/moisture in the decking
material in the event of a roof leak, which would be undetectable
until after the roof sheathing sufficiently decayed. To achieve the
specified ventilation and moisture management in attics, attic
baffles or vent chutes which are elongated channels, are commonly
used to preserve a ventilation path between the roof deck and
fibrous insulation placed on the attic floor. A wide variety of
these components are commercially available, including ones made
from vacuum-formed XPS sheets, solid PS, and cardboard. An example
of an XPS attic vent is marketed by Owens Corning.
[0059] The following non-limiting example serves to illustrate the
invention.
EXAMPLE 1
[0060] This Example details the test procedure to determine the
ultimate wind uplift load for roof/wall panels reinforced with a
closed-cell spray polyurethane foam. It is based on a slightly
modified version of ASTM E330-02 "Standard Test Method for
Structural Performance of Exterior Windows, Doors, Skylights and
Curtain Walls by Uniform Static Air Pressure Difference" using a
test wind uplift test arrangement.
Test Panel Construction:
[0061] A structural member is formed according to the configuration
shown in FIG. 1 and FIG. 2. The structural test panel comprises an
array of five parallel 2''.times.4'' by 72'' spruce-pine-fir
dimensional lumber beams spaced on 24'' centers. A 7/16'' oriented
strand board (OSB) sheet is fastened to the inside surface of the
OSB by nails. The fasteners used were 6d ringshank nails applied
using a pneumatic nail gun. Spacing of the ringshank fasteners was
6'' for the two framing members at each end. Spacing of the
ringshank nail fasteners on the three inner framing members was on
12'' centers. 10 specimens were installed with ring-shank nails
only, 13 specimens having a SPF fillet along the rafters and 5
specimens having full SPF coverage over the panels. After
fastening, a closed-cell spray polyurethane foam (ccSPF), 2.0
lb/ft.sup.3, was applied to some of the specimens, as shown in FIG.
3 in a filleted fashion and FIG. 4 in a full layer fashion
according to this invention. For the filleted foam specimens, 13
panels were sprayed with a single pass at the rafter to sheathing
joint forming a fillet of 3'' high, 5-6'' wide of a polyurethane
closed-cell spray foam. Fillets of foam insulation were sprayed
along the interface of the sheathing and the 2.times.4's. For the
full layer application, 5 specimens are fully covered from truss to
truss with a 3'' thick layer of the foam insulation. The
polyurethane was InsulStar ccSPF polyurethane manufactured by NCFI
Polyurethanes. After application, the test panels were stored for
more than two weeks at a warehouse prior to the start of testing so
that the foam is allowed to cure to achieve optimum bond strength.
The spray is pumped through separate lines from steel barrels. The
chemicals are combined at the nozzle of the spray gun and dispersed
under a pressure of 1,000 psi. The foam immediately increases in
volume once it is applied to a surface.
Test Procedure
[0062] The panel specimens were placed in an upside down position
in a test frame. The approximate dimensions of the top opening of
the test frame are about 5 ft.times.9 ft. When centered in the test
frame the OSB sheet is suspended by the dimensional lumber, which
spans across the 5 ft dimension of a test frame. A polyethylene
sheet is then draped carefully across the test panel, and cut so
that it is just even with the bottom of the test frame. The
polyethylene sheet is then sealed to the bottom of the test frame
with duct tape.
[0063] A vacuum pump is turned on, and a vacuum valve is opened
slightly to evacuate the test frame. This pulls the polyethylene
sheet over the test panel. Care is taken to be sure the
polyethylene sheet drapes evenly over the test panel without
excessive folding to prevent risk of leakage. Any leaks that may
develop are sealed with duct tape. After an initial removal of air,
a vacuum is applied at an even, controlled rate. At pre-defined
pressure increments, the panel is allowed to sit for approximately
15-30 seconds before the pressure is increased to the next
increment.
[0064] Vacuum pressure is controlled and monitored on a digital
gage until failure. Failure is readily noticeable, producing a
distinctly visual and audible sound at failure. Failure typically
occurs by a failure of the connection between the OSB and
dimensional lumber. At the point of failure, the maximum pressure
recorded by the digital pressure gage is then recorded. This
pressure (vacuum) is then converted to pounds per square foot, and
becomes the measured wind uplift load.
[0065] In a typical failure of a no-foam specimen, the heads of the
nails are pulled through the OSB sheathing, without the nails being
pulled out of the truss itself. In at typical failure of the foam
fillet test specimen, delamination occurs between the truss and
foam occurs. Once this has occurred, the nail heads are immediately
pulled through the OSB in a similar manner as a no foam
specimen.
Test Results
[0066] Two specimens of each type (no foam, filleted foam and
uniform fill foam) were tested. On one of the uniform fill
specimens, the nail heads were ground off to simulate removal of
the nails. The table below contains a summary of the results.
TABLE-US-00002 TABLE Summary of SPF Samples Wind Uplift Test
Results. Ultimate failure pressures of 4 ft by 8 ft OSB sheathing
fastened using 6d ring shank nails to 2 in. by 4 in. wood members.
No foam Fillet Full foam Pressure (psf) Pressure (psf) Pressure
(psf) 88 158 252 70 126 285 100 165 267* 46 154 238 85 163 180 85
192 71 179 90 106 71 106 71 168 168 135 170 Mean value (psf) 78 153
244 Std. Dev. (psf) 15 27 40 No. of Samples 10 13 5 Confidence
Level 10.8 16.2 49.7 (95%) (psf) *Specimen tested with nail heads
removed from sheathing
DISCUSSION
[0067] The results show there are significant differences in
ultimate failure capacities among the three groups of data with the
full foam layer coverage producing the greatest increase in
ultimate failure capacity over the non-retrofitted panels. Because
only 5 full-foam samples were included in the sample results, the
95% confidence level for the mean failure capacity is relatively
large as compared to the mean (20.3%). For the completed test
sequence, the 95.sup.th percentile confidence level was 13.9% and
10.6% respectively, for the no foam and fillet samples.
[0068] Statistical T-tests showed sufficient evidence to reject the
hypothesis that the mean failure loads of the three categories are
the same at the 95.sup.th percentile level. Analysis of the results
show that the application of the spray-applied polyurethane foam to
roof sheathing samples produces a definite increase in the ultimate
wind uplift capacity of these samples. Both methods of foam
application (fillet and full foam coverage) significantly improve
the performance of the roof sheathing to support connection. The
results show a substantial improvement in wind resistance by the
uniformly filled full foam coverage samples compared to the
filleted samples.
[0069] While the present invention has been particularly shown and
described with reference to preferred embodiments, it will be
readily appreciated by those of ordinary skill in the art that
various changes and modifications may be made without departing
from the spirit and scope of the invention. It is intended that the
claims be interpreted to cover the disclosed embodiment, those
alternatives which have been discussed above, and all equivalents
thereto.
* * * * *