Patent Application
20130205708
The present application claims the priority benefit of Canadian Patent Application Serial No. 2,768,697, filed Feb. 15, 2012, and Canadian Patent Application Serial No. 2,789,509, filed Sep. 14, 2012, the entire contents of which are hereby incorporated by reference herein.
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.
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 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.
U.S. Pat. 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 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.
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 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;
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.
These and other features of the invention will become more apparent from the description in which reference is made to the following appended drawings.
a 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.
b 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.
c 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.
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.
A plurality of prefabricated spaced-apart rafter trusses 32 (shown in part in
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
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
As shown in
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 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
As shown in
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 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 lie flat on or contact on the top or sill plate 30.
As shown in
As shown in
Shown in
As shown in
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
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
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
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 (e.g. as available from Premium Spray Products, Canada), Anna Foil VB (95% heat reflective), SoloReflex (97% heat reflective), or other material as known in the art.
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.
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″×4″ studs and the walls and header plates were made using 2″×6″ studs. A standard vapour barrier was installed on the ceiling. A roof made of ½″ plywood was affixed on top of the ceiling joists and trusses. The roof was coated with black/grey rubber coat to simulate standard shingles.
Temperature measurements were taken using standard mercury thermometers or FLIR (forward looking infrared) camera (FLIR™ 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:
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.
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).
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 wanner 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.
Although the present invention has been described with reference to particular means, materials and embodiments, from the foregoing description, one skilled in the art can easily ascertain the essential characteristics of the present invention and various changes and modifications can be made to adapt the various uses and characteristics without departing from the spirit and scope of the present invention as described above and as set forth in the attached claims.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2768697 | Feb 2012 | CA | national |
| 2789509 | Sep 2012 | CA | national |
