Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Insulated/Soffit Rafter Vent
FIELD OF INVENTION
The present invention relates to the ventilation of attics and roof
undersides. More
particularly, the present invention relates to a unitary insulated vent chute
and blocking
assembly that can be used to provide ventilation to attics and prevent
insulating material,
particularly loose fill insulation, from blocking that ventilation.
BACKGROUND OF THE INVENTION
It has been known to provide various forms of baffles in roofing structures to
direct or
channel air along the underside of the roof, usually from the soffit area of
the roof upwardly
into an attic space or toward the vent ducts. Such baffle vents often are
referred to as vent
chutes. The vent chutes primarily direct the air against the under surface of
the roof thereby
keeping the roof deck cooler, preventing ice damming in the winter and
eliminating the build-
up of attic moisture. The vent chutes may also provide barriers to separate
the interior surface
of the roof from the attic area and from installed insulation, such as
fiberglass bats, blankets,
fiberglass and cellulose loose fill which is located on top of the ceiling
from blocking the
natural air flow from the ventilated soffit up through the vent ducts.
A typical vent chute currently being used is the egg-crate style vent chute.
Egg-crate style
vent chutes are affixed to the underside of the roof and are typically
elongated members that
have a roof facing side and define at least one channel on the roof facing
side for directing
ventilating air from the soffit to the space above the attic area. While these
vent chutes are
able to increase ventilation, they do not contribute any insulation capacity
in a building
construction. Furthermore, these egg-crate style vent chutes do not act as
blocking bodies for
any installed insulation overtop the ceiling from exiting the eaves area and
blocking the
airflow. Also, this type of vent chute does not provide a full width of air
flow from one rafter
to the other. Rather, depending on the style, it will typically provide about
two thirds to three
quarters of the maximal air flow possible.
Another typical vent chute currently used is the cardboard style vent chute.
These vent
chutes are relatively inexpensive to manufacture and may be configured to act
also as baffles
so that installed insulation is prevented from exiting the eaves area and
blocking the airflow,
however, they suffer from significant drawbacks. First, they are made of paper
and
accordingly, are susceptible to moisture. Consequences of moisture include
eventual mold
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formation in the attic space and/or vent chute. Additionally, the moisture can
decrease
insulation capacity of the installed insulation located on top of the ceiling.
Second, the
cardboard style vent chutes are not insulated and therefore do not contribute
to any insulation
capacity in a building construction.
US Patent No. 7,101,608 (US '608 patent) describes an eaves vent insulation.
US '608 patent
provides a preformed block of foam insulation that is for horizontal placement
between
ceiling joists that has interspersed on an attic facing surface, a series of
ridges and valleys.
The valleys afford passageways for the air to circulate through the soffits
and out the attic
vents. The foam is tapered from front to back at an angle that mimics the
pitch of the roof. A
It) significant drawback of US '608 patent is that the block of foam is set
at a fixed angle and
therefore the same block of foam is generally not to be used in two roofs
having a
substantially different pitch, unless significant modifications are made.
US Patent Application Publication No. 2004/0134137 describes a unitary vent
chute and
insulation dam body that provides ventilation to an open attic space. The body
is formed
from polyolefin foam and includes surface channels, internal conduits, or both
to promote air
flow. The body is inserted between rafters and one end of the body abuts
against a roof deck
without closing off surface channels and a bottom end is fastened near the top
of the structure
exterior wall. A bend in the body is formed proximate the bottom end by
bending the body
over the exterior wall.
Accordingly, there is a present need for a unitary insulated vent chute and
blocking assembly
that overcomes the limitations seen in currently used vent chutes and
combination vent chute
and blocking assemblies.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved vent chute and
blocking assembly.
Accordingly, the present invention relates to an insulated vent chute and
blocking assembly
which can be inserted between adjacently disposed roof rafters of a building
construction
having a pitched or flat roof, the roof being supported by a building wall.
The assembly
comprises: a generally flexible insulated body having a roof facing surface,
an attic space
facing surface, the surfaces spaced apart from each other to define a pair of
longitudinal rafter
facing sides, a top and a bottom transverse end, the ends connecting the
sides; and a reflective
substrate covering the attic space facing surface, the substrate for
reflecting heat away from
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the attic space facing surface and back into attic insulation. The assembly is
fabricated from a
flexible insulated material, and can assume an arcuate form in embodiments
when the body is
inserted between adjacently disposed roof rafters in the building construction
with a pitched
or flat roof such that the bottom transverse end can contact the top of the
building wall.
In certain non-limiting embodiments, the unitary insulated vent chute and
blocking assembly
provides for greater airflow in the attic and prevents the installed
insulation above the ceiling
from exiting the eaves region of the attic.
In further non-limiting embodiments, the unitary insulated vent chute and
blocking assembly
provides increased insulation in the eaves region of the attic, and directs
heat emanating from
the installed insulation back towards the attic space and away from the roof.
The present invention also relates to a method for making a unitary insulated
vent chute and
blocking assembly as described above. The method comprises:
providing a generally flexible insulated body having a roof facing surface, an
attic space
facing surface, the surfaces spaced apart from each other to define a pair of
longitudinal rafter
facing sides, a top and a bottom transverse end, the ends connecting the
sides;
providing a reflective substrate;
applying a bonding material to at least one of the attic space facing surface
and the reflective
substrate; and
layering the reflective substrate to the body so that the reflective substrate
covers the attic
space facing surface.
The invention also relates to a method for establishing and maintaining air
flow under a
pitched or flat roof of a building construction between a soffit region and an
attic space, the
building construction comprising an exterior wall, a ceiling supported by the
wall, a roof
including a plurality of rafter trusses supported by the wall where each truss
includes ceiling
joist segments and two intersecting, but opposed, rafter segments, and a roof
deck supported
by the rafter segments, the method comprising:
providing a unitary insulated vent chute and blocking assembly as described
above;
sliding the assembly between adjacently disposed rafter segments so that the
reflective
substrate faces inwards and towards the building interior and so that the roof
facing surface of
the body faces outwards and towards the roof;
orienting the bottom transverse end so that it contacts the top of the wall;
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bending the assembly so that the body assumes an arcuate form and forms an
angle
relative to the balance of the assembly that is approximates to the pitch of
the roof; and
securing the assembly to adjacently disposed rafter segments.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more apparent from the
description in
which reference is made to the following appended drawings.
FIGURE 1 is a perspective view of a portion of a building construction showing
a unitary
insulated vent chute and blocking assembly according to one embodiment of the
present
invention mounted at the intersection of an outside wall, attic joist and roof
rafters in
accordance with an aspect of the present invention.
FIGURE 2 is a cross-sectional side view of a portion of a building
construction showing a
unitary insulated vent chute and blocking assembly according to one aspect of
the present
invention mounted at the intersection of an exterior wall, attic joist and
roof rafters.
FIGURE 3 is a perspective view of a unitary insulated vent chute and blocking
assembly
according to an embodiment of the assembly in an unbent configuration.
FIGURE 3a is a perspective view of a unitary insulated vent chute and blocking
assembly
according to another embodiment of the assembly in an unbent configuration
where tabs are
provided.
FIGURE 3b is a perspective view of a unitary insulated vent chute and blocking
assembly
according to another embodiment of the assembly in an unbent configuration
where tabs are
included.
FIGURE 3c is a perspective view of a unitary insulated vent chute and blocking
assembly
according to yet another embodiment of the assembly in an unbent configuration
where tabs
are included.
FIGURE 4 is a side view of a unitary insulated vent chute and blocking
assembly according
to another embodiment of the assembly that is bent and able to assume
different arcuate
forms.
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DETAILED DESCRIPTION
The present invention relates to a unitary insulated vent chute and blocking
assembly that
provides for greater airflow in the attic and for increased insulation in the
eaves region of the
attic. The device also prevents the installed insulation above the ceiling
from exiting the
eaves region of the attic and directs any heat emanating from the installed
insulation back
towards the attic space and away from the roof, for example, by using a
reflective surface
material. The assembly thus reduces the transfer of heat from the living space
and/or attic
space toward the roof deck. The present invention can be used to provide
greater ventilation
to attics and roofs and to increase the insulation capacity near the eaves
region of a new
building construction or an existing building retrofit.
The present invention will be described hereafter with reference to the
attached drawings
which depict non-limiting embodiments of the invention.
FIGURES 1 and 2 illustrate a typical building construction 20 that includes an
exterior wall
22, a ceiling 24 and a roof 26. Wall 22 comprises a plurality of spaced-apart,
vertical studs
28 (2" x 6" studs, for example), wall sheathing (not shown) and a top or sill
plate 30
connected to upper ends of the studs 28.
A plurality of prefabricated spaced-apart rafter trusses 32 (shown in part in
FIGURES 1 and
2) (2" x 4" studs, for example) rest on the top/sill plate 30. Each rafter
truss 32 comprises a
ceiling joist segment 34 (2" x 4" studs, for example), an end portion of which
rests on and is
secured to the top or sill plate 30 of wall 22 and two intersecting, but
opposed, rafter
segments 36 (only a part of one rafter segment is shown in FIGURES 1 and 2).
Ceiling 24 comprises the ceiling joist segments 34 of a plurality of spaced-
apart rafter trusses
32 and a surface layer 38 formed by sheets of plaster board 38a or other
interior surface
material and a vapour barrier 38b. Surface layer 38 is attached to undersides
of joist
segments 34 to form ceiling surfaces for interior rooms of the building
construction 20.
Insulation 40, in the form of batts or blankets or blown in or loose fill
insulation, may be
disposed between ceiling joist segments 34 of successive rafter trusses 32.
Roof 26 includes the plurality of spaced-apart rafter trusses 32 and a roof
deck 42 (a portion
of the roof deck is shown in Figures 1 and 2)that is composed of a layer of
sheathing or
plywood attached to upper surfaces of rafter segments 36 of the rafter trusses
32. Roof deck
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1
42 is, in turn covered by a layer of barrier material 44. Tar paper, for
example, functions as a
suitable barrier material 44. An outer roofing material 46, such as a layer of
shingles,
overlays barrier material 44. Roof 26 desirably includes at least one venting
mechanism 48
(not shown). Suitable venting mechanisms 48 include, without limitation,
louvered ridge
vents. As shown in Figure 2, there is a space which permits air flow between
the roof deck
and a roof facing surface of the body of the vent chute and blocking assembly
80. This space
is shown in the figure as distance 'd'. Without wishing to be limiting in any
way, the
preferred minimum dimension for distance d, and hence the preferred minimum
space
between the assembly 80 and roof deck 42 to allow for the venting air flow
passageway, is
approximately one inch.
Building construction 20 includes an attic space 50 bounded by the top or sill
plate 30, ceiling
24 and roof 26. Attic space 50 may have venting mechanisms 52 (not shown) in
addition to
or in place of venting mechanisms 48. Venting mechanisms 52 include, without
limitation,
louvered vents over an aperture (not shown) in a building exterior wall (not
shown) near a
roof peak formed when cooperating rafter segments 36 meet at a point distant
from sill plate
30.
A facia board or panel 52 abuts lower ends of rafter segments 32. A soffit 54
spans a space
between, and is secured to, the exterior wall 22. A soffit vent (not shown) is
provided in
soffit 54 to facilitate flow of air through soffit 54 and into attic space 50.
If either or both of
venting mechanisms 48 (e.g. ridge vents) and venting mechanisms 52 are present
in building
construction 20, the flow of air continues through attic space 50 and out of
the venting
mechanisms 48, 52, or both.
According to the unitary insulated vent chute and blocking assembly of the
present invention,
a plurality of unitary vent chute and blocking assemblies 80, one of which is
shown in
FIGURE 3, are inserted between adjacent rafter joist segments 36 as shown in
FIGURES 1
and 2.
As shown in FIGURE 3 each assembly 80 is a generally rectangular insulated
body 82. The
body 82 has a bottom transverse end 84 that, when used in an building
construction 20, rests
on, contacts or may be operatively connected to a top or sill plate 30.
Each assembly 80 also has a top transverse end 86 that is spaced apart from
the bottom
transverse end. Each assembly 80 has a roof facing surface 88. The roof facing
surface 88
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has a generally planar surface. The planar surface facilitates airflow between
the soffit vent
in the soffit 54 and the attic space 50, because the planar surface allows for
the full width of
the body 82 to contribute to air flow. As will be appreciated when used in a
building
construction 20, the roof facing surface 88 will form part of a venting
airflow passageway (d)
that facilitates the flow of air entering through the soffit vent in the
soffit 54 to the attic space
50.
Each assembly 80 also has an attic space facing surface 90. The attic space
facing surface 90
and the roof facing surface 88 are spaced apart from each other and define a
pair of rafter
facing sides. As will be appreciated when used in a building construction 20,
and as seen in
greater detail in FIGURE 2, a portion of the attic space facing surface 90
will act as an
installed insulation dam. In other words, the assembly 80 provides a barrier
to passage of
loose fill insulation 40 from the attic space into an area bounded in part by
the soffit, known
as the soffit region or eaves region, when the bottom transverse end 84 is
made to lie flat on
or contract the top or sill plate 30. In addition, the assembly 80 provides a
further barrier to
prevent air, wind and moisture entering through the soffit vent from
penetrating into the attic
insulation 40. While the assembly 80 is shown to be substantially planar in
FIGURE 3 it will
be appreciated that the assembly 80 will be made to assume an arcuate form or
profile as
shown in FIGURES 1 and 2 when used in a building construction 20.
As shown in FIGURE 1, A plurality of retainers 92, such as flat headed nails
or shingle nails,
may optionally be inserted in the top or sill plate 30 so that at least a
portion of the assembly
80 abuts against the retainers 92 to keep the bottom transverse end 84 of the
assembly 80
from shifting from its rest position and moving into the soffit region. When
the retainers 92
are secured to the top or sill plate 30, a portion of the roof facing surface
88 abuts against the
retainers 92 and on the other side, a portion of the attic space facing
surface 90 abuts against
the loose fill insulation 40. The insulation dam created thus prevents loose
fill insulation 40
from spilling over the top or sill plate 30 and blocking the soffit vent 56 in
soffit 54 in the
eaves region, and provides greater insulation properties in the corners of the
attic space.
The assembly 80 is secured, preferably by friction fit to fit snugly between
adjacent rafter
segments 36. As will be appreciated, the body 82 of the assembly 80 will
assume an arcuate
form when installed in the building construction 20. This is because the
assembly 80 will
generally follow the pitch of the roof 26 as it will be guided by the angle
made by the roof
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rafter segments 36. The assembly 80 will then have a bend in the body 82 so
that the bottom
transverse end 84 can be made to made to lie flat on or contact on the top or
sill plate 30.
As shown in FIGURE 4 the degree of bending of the body 82 will depend on the
pitch of the
roof 26 of the building construction 20. The assembly 80 of the present
invention is readily
adaptable to many types of roofs 26 with different pitch angles because the
degree of bending
can be easily and conveniently controlled by the installer on-site of the
building construction
so that the angle is similar to pitch of the roof, and at the same time
provide for improved air
flow as described above.
As shown in FIGURES 3, 3a, 3b, and 3c, a reflective substrate 100 covers - or
is otherwise
layered over - the attic space facing surface 90 of the body 82. The
reflective substrate 100 is
for reflecting heat away from the attic space facing surface 90 of the body
82. The result
being that any heat that convects through the loose fill insulation or batt
insulation 40 will be
reflected back down into the attic space 50. The reflection of heat emanating
from the
interior of the building away from roof sheathing and back (inward) towards
the building
interior is especially important in the soffit region because this will allow
most buildings
using the assembly 80 of the present invention to meet the building codes for
R-values in the
attic around the perimeter walls. Currently, because of a combination of roof
pitch and rafter
design used in a majority of new constructions and existing construction
retrofits, the R-
values in these areas cannot meet the building codes because of cold air drop
and lack of
proper depth of insulation due to the narrow depth near the soffit/top sill
plate 30. The
assembly 80 of the present invention addresses these deficiencies seen in
existing vent chutes
currently used by builders.
Shown in FIGURES 3a, 3b, and 3c are embodiments of the invention where the
reflective
substrate 100 includes tabs 102, 104, 104', and 106 that extend beyond the
transverse width
of the body and/or beyond the longitudinal length of the body. When the tabs
102 extend
beyond the transverse width of the body they are for sealingly attaching the
assembly 80 to
adjacent rafter segments 36. When the tabs 102 extend beyond the longitudinal
length of the
body, particularly at the bottom transverse end 84, they are for sealingly
attaching the
assembly 80 to the top or sill plate 30 or the ceiling 24.
As shown in FIGURES 3b and 3c, in embodiments of the invention, the reflective
substrate
100 may only have tabs that extend beyond the transverse width of the body
along the entire
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4.
longitudinal length 104 (FIGURE 3b) or partially 104' (FIGURE 3c). Similarly,
the
reflective substrate 100 may only have tabs that extend beyond the
longitudinal length of the
body 106 or partially 106' (not shown). It will be appreciated that the tabs
102, 104, or 106
serve as sites for attachment to any portion of the rafter segments 36 or top
or sill plate 30 or
even ceiling 24 by any suitable fastener such as for example nails, staples or
adhesives.
The tabs 102, 104, 104', and 106 also serve as a water tight seal between the
body 82 and the
adjacent rafter 36 and/or the top or sill plate 30. It will also be
appreciated that the reflective
substrate 100 also provides the additional benefit of strengthening the area
where the body 82
is bent.
The unitary insulated vent chute and blocking assembly 80 will have a length
(e) of about 3
to about 4 feet as depicted in FIGURES 1 to 4. In some preferred, yet non-
limiting
embodiments, the assembly 80 will have a length of about 4 feet. However, in
practice, the
assembly 80 could be provided in any suitable length that would be sufficient
to provide the
venting air flow passageway (d) for air to enter an eaves area through the
soffit vent 54 and
travel upward through and into the open attic space 50. The assembly 80 can be
any length
that is useful for providing a venting air flow passageway (d) that extends
from the eave area
to a position at or near vents 48 or 52 provided at the ridge of the roof as
for cathedral or
vaulted ceiling applications. It is to be understood that multiple sections of
the assembly 80
could be abutted together or overlapped to extend to any desired length. Also,
the assembly
80 can of course be cut to any shorter lengths to adapt to different building
constructions 20
and situations.
The unitary insulated vent chute and blocking assembly 80 of the present
invention will have
a thickness dimension (f) that is dependent on both the type of insulation
material used to
manufacture the body 82 and to satisfy any vapor barrier requirement. The
thickness
dimension is measured from the attic space facing surface 90 to a point on the
roof facing
surface 88 perpendicular to the point in the attic space facing surface 90. In
embodiments of
the invention, the thickness dimension is at least two inches (2"). In another
embodiment of
the invention, it is less than three inches (3"). It will be appreciated that
the thickness
dimension can be any length as long as it is less than the thickness of a
rafter segment 36 so
as to provide enough clearance to form part of the venting air flow passageway
(d) as shown
in FIGURES 1 and 2.
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It is generally recommended that the body 82 have at least an R-value of R-10,
although it is
recommended to have R-20 or higher. In embodiments of the invention, the R-
value of the
assembly 80 will typically range between about R-10 to about R-26, and may in
preferred
embodiments be about R-20. However, one skilled in the art would appreciate
that the R-
value of the assembly 80 may have a total R-value that matches the R-value of
the building
wall so that there is a consistent R-value throughout the entire building
construction. In
addition, the reflective substrate 100 may beneficially increase the R-value
of the assembly
80, depending on the material used, which contributes overall to the total R-
value at the
perimeter of the building, including loose fill insulation 40. The typical R-
value code for the
walls of a building construction is at present R-20, but in certain areas may
be about R-32.
The unitary insulated vent chute and blocking assembly 80 has a width (g) of
about the
distance between adjacent rafter segments 36 in a building construction 20.
This is so that
the assembly 80 can fit snugly, by friction fit, between adjacent rafter
segments 36. In a
typical building construction 20 the distance between adjacent rafter segments
36 is about 22
inches, therefore the assembly 80 of the present invention may have, without
wishing to be
limiting in any way, a desired width of about 22 inches in many embodiments.
It is,
however, to be understood that the assembly 80 is readily adaptable to
different distances
between adjacent rafter segments 36 because the installer can easily customize
the width of
the assembly 80 at the site of installation by cutting the assembly 80 with
readily available
tools.
The unitary insulated vent chute and blocking assembly 80 desirably has a
stiffness sufficient
to allow a portion of the assembly 80 that is subjected to a force sufficient
to bend, without
breaking, to form an angle relative to the balance of the assembly 80 (e.g.
from vertical to
horizontal) that is similar to the pitch of the roof 26 in a building
construction 20.
When the body 82 is not inherently very flexible and, for example, is formed
from semi-rigid
foam or a rigid foam, the body 82 may advantageously be provided with a
plurality of
transverse cuts (horizontal slits) 108 formed in the attic space facing
surface 90 proximate or
near the bottom transverse end 84 (and thus distal or away from the top
transverse end 86) to
allow a portion of the body 82 that is subjected to a force sufficiently to
bend, without
breaking, and form an angle relative to the balance of the assembly 80 that is
similar to the
pitch of the roof 26 in a building construction 20. As shown in FIGURES 3, 3a,
3b, and 3c,
yet without wishing to be limiting in any way, the plurality of transverse
cuts 108 may start
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from about 5 inches and extend up to about 10 inches from the bottom
transverse end 84. In
certain preferred yet non-limiting embodiments, the plurality of transverse
cuts 108 start from
about 5 inches and extend to about 8 inches from the bottom transverse end 84.
It will also be appreciated that the body 82 may optionally include one
transverse cut 108'
(not shown) in the attic space facing surface 90 adequate to facilitate
bending of the body 82.
It will be appreciated that the plurality of transverse cuts 108 or one
transverse cut 108'
made across the width of the semi-rigid or a rigid foam will allow the body 82
to bend more
easily. It will also be appreciated that the transverse cuts 108 or cut 108'
can be at any
distance away from the bottom transverse end 84 so long as: (1) an insulation
dam of
sufficient height is created for the installed insulation 40; (2) the assembly
80 assumes an
arcuate form that approximates the angle of the rafter segments 36 in the
pitched roof 26 and;
(3) the assembly 80 provides a venting air flow passageway (d) that extends
from an eave
area.
The body 82 can be an extruded foam board or block, or can be fabricated from
foamed
plastic such as polyurethane or polyolefin foam, and most desirably,
polystyrene foam. It is
generally desirable to have the body manufactured from flexible materials to
facilitate
bending. In certain non-limiting embodiments of the invention, the types of
materials that
can be used include polyurethane, polyethylene, ethylene vinyl acetate,
expanded
polystyrene, polyvinyl chloride (PVC), cross-linked polyethylene, latex,
neoprene, ethafoam,
syntactic foam, as well as other materials as known in the art. In the
experiments that follow,
an ethafoam material was used for testing purposes. Flame resistant materials,
such as
trisphosphate, hexabromocyclododecone, or equivalent materials can also be
added to the
base material of the body 82.
The reflective substrate 100, in preferred embodiments, will generally
comprise a reflective
film or foil, or more particularly, the reflective film may be a reflective
metal film such as an
aluminum film. In other embodiments, the reflective film may be a reflective
polymeric film
such as reflective plastics, composite materials and laminate materials.
Without wishing to
be limiting in any way, the substrate 100 may comprise a non-woven
polypropylene material
with aluminum or plastic silver coated aluminum, a poly-urea or acrylic
reflective material
TM
(e.g. as available from Premium Spray Products, Canada), Anna Foil VB (95%
heat
TM
reflective), SoloReflex (97% heat reflective), or other material as known in
the art.
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The reflective substrate 100 may also be a coating that can be applied to the
attic space facing
surface 90.
In certain embodiments, the reflective substrate 100 can be affixed to the
body 82, using any
known type of fastener. Exemplary fasteners include, but are not limited to,
staples, nails, or
adhesives. The reflective substrate 100, may for example, be layered over the
attic space
facing surface 90, followed by bonding using an adhesive (e.g. which may have
been
previously applied to either the attic space facing surface 90 or to the
reflective substrate
100). As will be appreciated, when the assembly 80 includes the plurality of
transverse cuts
108 or one transverse cut 108', the cuts in the body 82 are done before the
reflective substrate
100 is layered over the attic space facing surface 90 to maintain the moisture
barrier property
of the reflective substrate 100.
In use, in a building construction 20, installation of the assembly 80 can
done before or after
roof 26 or the ceiling materials (drywall, vapour barrier, etc.) are put in
place. A worker
optionally first fixes retainers 92 to the top or sill plate 30 from within
the attic space 50. The
worker can then slide most of the length of an assembly 80 between adjacent
rafter segments
36, by friction fit, with the roof facing surface 88 toward the roof deck 42.
The bottom
transverse end 84 is lowered and rests on or contacts the top or sill plate
30. The bottom
transverse end 84 is then optionally made to abut against the retainers 92,
and then the worker
bends a portion of assembly 80 proximate to the bottom transverse end 84 so
that the balance
of the assembly 80 assumes an arcuate form that approximates the pitch of the
roof 26 and
allows enough clearance to form the venting airflow passageway (d). During the
bending
process, the bottom transverse end 84 is prevented from shifting and moving
into the soffit
region by retainers 92 where a portion of the assembly 80 abuts against the
retainers 92.
There is generally no need for a second worker to stand in attic space 50 to
guide assembly
80 into place. If tabs 102 (104, 104' or 106) are provided, the worker then
attaches the tabs
to the rafter segments 36 or the top or sill plate 30 to further secure the
assembly 80 to the
adjacent rafter segments 36.
As will be appreciated, the assembly 80 is also well suited for retrofitting
existing building
constructions, since the assembly 80 can be installed from entirely within
attic space 50.
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1µ
Examples
In this example, two types of soffit vent systems currently used: the egg-
crate style soffit vent
chute (#1) and the cardboard style soffit vent chute (#2) were compared
against an example
of the assembly as described (#3). A model building construction was built
having a standard
roof pitch of 4/12 and a 12" overhang. The ceiling joists and ceiling trusses
were made using
2" x 4" studs and the walls and header plates were made using 2" x 6" studs. A
standard
vapour barrier was installed on the ceiling. A roof made of Y2" plywood was
affixed on top
of the ceiling joists and trusses. The roof was coated with black/grey rubber
coat to simulate
standard shingles.
to Temperature measurements were taken using standard mercury thermometers
or FLIR
(forward looking infrared) camera (FLIRTM i7). Temperature measurements were
taken of
the three soffit vent systems mentioned above at various locations including:
the attic space,
roof (top and underside), ceiling, cellulose insulation, and the vent chute.
As a control,
temperature measurements were also taken before and after the addition of the
cellulose
insulation. The steps taken to acquire the temperature measurements are
outlined below:
Steps:
1. Egg crate installed ¨ no cellulose: temperatures measured on vent chute
temperatures measured on the air flow
temperatures measured on roof
2. Cardboard installed - no cellulose: temperatures measured on vent chute
temperatures measured on the air flow
temperatures measured on roof
3. Foam/Reflective Assembly installed ¨ no cellulose:
temperatures measured on vent chute
temperatures measured on the air flow
temperatures measured on roof
4. Foam/Reflective Assembly installed ¨ cellulose installed:
temperatures measured on vent chute
temperatures measured on the air flow
temperatures measured on the cellulose
temperatures measured on roof
temperatures measured on the ceiling
CA 02789509 2012-09-14
5. Cardboard installed ¨ cellulose installed:
temperatures measured on vent chute
temperatures measured on the air flow
temperatures measured on the cellulose
temperatures measured on roof
temperatures measured on the ceiling
6. Egg crate installed ¨ cellulose installed:
temperatures measured on vent chute
temperatures measured on the air flow
temperatures measured on the cellulose
temperatures measured on roof
temperatures measured on the ceiling
Notes:
(i) In steps 1 to 3 the same construction apparatus was used, and
approximately 10
minutes was needed to change the chute system over (i.e. from egg crate style
¨> cardboard
style ¨> foam/reflective assembly style). Another 15 minutes of acclimation
time was
allowed before taking measurements so that stable temperatures were obtained.
(ii) In steps 4 to 6, approximately the same amount of time (-10 minutes)
was taken to
change the chute system over (i.e. from foam/reflective assembly style ¨>
cardboard style ¨>
egg crate style). Another 20 ¨25 minutes of acclimation time was allowed
before taking
measurements to allow for the cellulose to absorb any heat and allow for
stable temperatures
to be obtained.
During the testing, the humidity was approximately 30-40% and the ambient
temperature was
86 degrees Fahrenheit. The amount of air flow of the vent chute can be
estimated by looking
at the recorded temperatures of the vent chute. In these tests, the higher the
observed
temperature of the vent chute would mean a greater airflow in the vent chute.
The results of
the experiment are shown in Table 1.
CA 02789509 2012-09-14
a
Table 1: Comparative testing results for three products tested. 1 ¨ egg crate
style, 2 ¨
,
cardboard style, and 3 - foam/reflective assembly style vent chute.
Site of temperature Product Initial Final Difference
(F)
reading # temperature (F) temperature (F)
Attic 1 108 120 +12
2 ' 79.7 116 +36.3
3 79.7 116 +36.3
Roof 1 156 157 +1
2 154 159 +5
3 157 148 -9
On the Products 1 109 123 +14
2 95.5 95.7 +0.2
3 83.1 94.6 +11.5
Ceiling 1 * 95.5 No change
2 * 95.7 No change
3 * 90.3 -6 (cooler)
Airflow (in the venting 1 106 125 +19
airflow passageway)
2 116 123 +7
3 79.7 116 +36.3
Cellulose insulation 1 88.5 116 +27.5
2 91.8 120 +28.2
-15-
CA 02789509 2012-09-14
,
3 83.7 88.7 +5
,
* An average of 15 minutes lead time was allowed to elapse before taking the
final
temperature in order to let temperatures stabilize. Initial temperatures were
not taken at the
time cellulose insulation was installed since this number was not pertinent to
the study.
Summary of results ¨ Egg-crate style vent chute
As can be seen from the results, the egg-crate style soffit vent did not
produce enough airflow
to move heat away from the complete underside of the roof. The result would be
a hotter
ceiling area and roof and during the winter months this would mean an
increased likelihood
of ice damming and colder perimeter walls. The insufficient airflow would also
mean this
type of soffit vent would also not be able to move away any moist air in the
vent chute. The
trapped moist air in the chute would increase the likelihood of wood rot,
mould and
premature shingle failure.
Summary of results ¨ Cardboard style soffit vent chute
The cardboard style soffit vent chute gave good airflow, better than the egg-
crate style vent
chute, before the addition of the cellulose insulation. However, the
insulation cannot be
added as deep in this area and thus it creates a vorticity which draws heat
out of the cellulose
and/or applies potential moisture into the cellulose. Thus, when the cellulose
insulation was
added, the benefit of increased airflow was offset by the fact that there was
a high amount of
heat absorption and transfer to the cellulose insulation. In addition, this
type of vent chute is
thin and there is no inherent insulation capacity. The material is also
susceptible to moisture
collection on the cardboard and deposition of the moisture into the cellulose
leading to
decreased insulation capacity and eventual mold formation.
Summary of results ¨ Unitary insulated vent chute and blocking assembly
The unitary insulated vent chute and blocking assembly included a 2 inch foam
body (with an
R-value of 10) with a reflective material adhered to the attic facing surface.
The assembly of
the present invention gave the highest airflow and accordingly, carried the
most air, heat and
moisture through the vent chute. This is evidenced by the larger relative
increase (36.3 F) in
chute temperatures from 79.7 F to 116 F when the cellulose insulation was
added. This is
compared with the 19 F difference with the egg-crate style of vent chute (#1)
and only a 7 F
difference the cardboard style of vent chute (#2).
46,
CA 02789509 2013-01-25
The roof temperature dropped by 9 F when the assembly of the present invention
was
installed. The ceiling temperature was also the lowest with the assembly of
the present
invention, but this only applies to the warmer months. During the cooler to
cold months the
temperatures would be higher (as they should normally) due to heat being
introduced into the
home via a hearing system. Therefore this assembly has a dual purpose. The
ceiling
temperature was 90.3 F with the assembly of the present invention, whereas the
ceiling
temperatures were 95.5 F and 95.7 F with the egg-crate style and cardboard
vent chutes,
respectively.
The temperature of the reflective substrate covering the attic facing surface
was low because
there was zero heat penetration of the air in the chute into the assembly
because of the
insulated body. Understandably, as time progressed, the temperature of the
reflective
substrate gradually rose because it was reflecting heat away from the assembly
back down
towards the attic space.
The temperature on the top of the cellulose insulation rose only 5 F using the
assembly of the
present invention. This is in contrast to the increases of 27.5 F and 28.2 F
with the egg-crate
style vent chute and cardboard style vent chutes, respectively.
Lastly, it will also be noted that the area near the top plate of the wall and
near the eaves area,
the R value for the egg-crate style and cardboard vent chutes were around R 15
to R16.
However, with the assembly of the present invention, the R value was around R
26. This
significant increase in R value is likely due to a number of factors. These
factors may
include: the ability of the reflective substrate to reflect reflective heat
back into the cellulose
insulation and down towards the attic space; the assembly does not suffer from
heat
penetration of the hot air in the vent moving into the attic space because of
the insulated
body. By the same token, one would not expect to see any heat loss from the
attic space near
the perimeter walls; and lastly, the assembly of the present invention does
not suffer from
moisture problems that plague some of the existing vent chutes.
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CA 02789509 2013-01-25
One or more currently preferred embodiments have been described by way of
example. It
will be apparent to persons skilled in the art that a number of variations and
modifications can
be made without departing from the scope of the invention as defined in the
claims.
48.
