Thermal Radiant Barrier for Use in Roof Insulation

Abstract

A thermal radiant barrier and methods of use are provided. The thermal radiant barrier includes a first elongated planar member and first and second walls projecting from opposite edges of the planar base. When in use, the thermal radiant base is affixed to the underside of roof decking with the first and second walls being affixed to the underside of the decking. An air passageway from the soffit vent along side the underside of the decking is created to permit the air to be channeled from the soffitt vent into the attic area alongside the decking. The temperature of the air is controlled by using material of an R-value recommended by the construction code of the region. The thermal radiant barrier may include a second elongated planar member hingeably connected to the first elongated planar member at an angle equal to the angel between the rafter and joist in a roofing structure. The second elongated member is positioned underlying Batt insulation in proximity to the soffitt vent and soffitt baffle. The second elongated member has an R-value recommended in the geographic location. In use, the R-value at an area of compressed insulation is given by the R-value of the second elongated member.

Description

FIELD OF INVENTION

This invention relates to pitched roof insulation. Particularly, the invention relates to the elimination of ice dams conditions.

BACKGROUND

Ice dams are formed when heat from the inside of a home escapes into the attic and warms the roof decking during the winter. FIG. 1 briefly illustrates the cross-section of an exemplary pitched roofing structure 100 that may be found in the prior art. Roofing structure 100 includes a decking 102 supported by rafter 104. A bottom most portion of rafter 104 is ordinarily affixed to an end portion of a joist 106. In proximity to the bottom most portion of rafter 104 and the end portion of joist 106 is an eaves 108, extending outwardly from an outer support wall 110 toward the underside of decking 102. Positioned in the eaves 108 is a soffit vent 112 which Permits air outside the roofing structure illustrated by air cloud 114 (“outside air 114”) having a temperature t_o to enter through soffit vent 112 into the attic area.

FIG. 2 is a frontal view of the underside, of roof structure 100 as seen from the perspective of one positioned in the attic space of a dwelling. Roofing structure 100 includes multiple roof rafters (i.e., multiple rafters 104) supporting decking 102. Rafters 104 may be regularly spaced one from another, for example by a distance d_r. Distance d_r may be chosen based on, for example, joist material, size, and environmental conditions. Distance dr is usually recommended by the building code authority of the geographic region.

As shown in FIG. 1 and FIG. 2, the outside air 114 enters through soffit vent 112 into the attic space to mix with attic air illustrated by cloud 116 (“attic air 116”) having a temperature t_e. Ice dams are created when the temperature t_e combines with temperature t_o thereby heating and melting snow on the outer side of decking 102. The melted snow then runs from the outer decking to the eaves 108 where it refreezes. The continual thaw and re-freeze process creates the ice dams. The result is water backing up under the roof shingles or behind fascia boards where it can soak through the roof decking or wall sheathing, causing damage to attics, ceilings and walls. Unchecked moisture can promote mold, mildew, and wood rot.

Ice dams can be prevented by keeping the difference in temperature of the attic air t_a and the outside air t_o as near to zero as possible. The mixing of the outside air 114 with the attic air 116 in the attic space tends to stabilize the temperature of the resulting mixed air in the attic space to near t_o+t_a. However, the temperature rising from the living space of a dwelling through the attic floor into the attic space works against the stabilizing affect of the mixing process. The heat of temperature t_l enters from the living space into the attic space through the attic floor 122. This living space heat of temperature t_l tends to raise the temperature of the attic space t_a to a temperature t_a+l_h which further promotes the melting and refreezing condition noted above.

Attic floor insulation 118 (i.e., Batt insulation) is added to prevent heat t_l from the living space (i.e. “living area”) of the home escaping into the attic raising the attic air temperature above the temperature of the outside air. Attic floor insulation 118 is ordinarily used to retard the flow of heat from the living space into the attic space. To ensure proper effective placement, the attic insulation 118 is ordinarily placed between joists 106 as close to soffit vent 112 as possible without obstructing the circulation of the outside air through the soffit vent 112 into the attic space. Insulation baffles 120 are used to ensure that soffit vent 112 remain unobstructed by the attic insulation 118.

One clear limitation to merely insulating the attic floor 122 is that the attic insulation merely retards the transference of heat t_l from the living space into the attic space. Heat still rises through the insulation 118. The ability of the attic insulation 118 to retard the heat transference is measured in resistance values (R-value). Insulation R-values are generally recommended by geographic zones. The higher the R-value, the greater the insulating power. For example, attic insulation 118 is ordinarily relegated to an average R-value of R38. Further still, the geographic zones may be organized by climate. Alternatively, geographic zones may be building or construction zones recognized by the building authority establishing the relevant R-value

Traditional roofing systems 100 have problems not addressed in the prior art. For example, attic insulation 118 is typically unrolled between joists 106 to soffit vent 112 to abut up against baffle 120. The attic insulation 118 nearest the baffle 120 is typically compressed (compressed insulation 124) as is shown in FIG. 1. When the attic insulation 118 nearest the baffles 120 is compressed the R-Value at the compressed insulation 124 is less that the R-value of the uncompressed portion of the insulation 118. This is because R-Value is a function of the thickness of the insulation and the material chosen. The compressed insulation portion permits the temperature t_l of the living space to transfer, more readily to the attic space. Temperature t_l raises the temperature of t_a creating ice dam conditions. Additionally, at the compressed insulation 124, a portion of the outside air 114 that traverses form the soffitt vent 112 escapes around the baffle 120 such that it gets trapped by the compressed insulation 124. The trapped air in the compressed insulation 124 then condenses and freezes causing ice formation at the soffitt vent 112.

Further, since insulation merely retards the transference of heat from the living area, the temperature of the attic air t₈ is typically higher than t_o by a factor of t_l, the amount transferring thorough the insulation. The result is that the temperature of the attic air t_a, especially against the underside of decking 102, is higher than the temperature of the outside air t_o promoting ice dam conditions.

What is needed is an article and method that ensures that even if the attic insulation near the baffles is compressed, the R-value in proximity to the compressed insulation remains at the recommended R-value of the geographic region.

What is additionally needed is an article or method that ensures that the air temperature on the underside of decking is kept near the temperature of the outside air t_o, so that ice damming conditions may be prevented. U.S. Pat. No. 5,341,612, issued Aug. 30, 1994 to Robbins, titled “Baffle Vent Structure” attempts to address this problem, but falls short. For example, the baffle vent structure disclosed is fabricated of extruded polystyrene foam material without concern for the restrictive value of the polystyrene foam material chosen. As such, the air the baffle directs against the underside of the decking continues to be adversely affected by the higher temperature of the attic area. Particularly, the air between the baffle and the underside of the decking is higher by an at least a portion of the temperature t_a.

SUMMARY OF INVENTION

In accordance with one embodiment of the present invention, a thermal radiant barrier for use in roof insulation is provided. The thermal radiant barrier according to the present invention is of the R-value required by the geographic region. A first portion of the thermal radiant barrier of the invention is formed to fit in between further controls the temperature of the air under a roof decking by channeling air from outside the roofing structure underneath the decking. The invention channels air from the soffit vent to the underside of the roof decking.

The thermal radiant barrier of the present invention may further include a second portion connected to the first portion at a first end such that the first and second portions are in a hinged arrangement. The thermal radiant barrier second portion is of substantially similar shape and the first portion. The second portion is formed to fit in between floor joists underlying the roof's ordinary Batt insulation. The area where the first portion and the second portion of the thermal radiant barrier are hinged is positioned abutting a soffitt vent. In this way, the second portion of the thermal radiant barrier ensures that the R-value at the compressed insulation remains at the recommended R-Value for the geographic region.

The first and second portions of the thermal radiant barrier of the present invention are elongated members. The first portion further includes a pair of longitudinal sidewall portions, traversing the first and second lengths of the first portion elongated member. The first portion of the thermal radiant barrier includes a roof facing side and an attic space facing side. The longitudinal sidewalls are affixed to the underside of the roof decking creating a passageway or channel for air to traverse from the soffit vent along the underside of the roof decking.

In another embodiment of the present invention, the thermal radiant barrier includes an attachment flanges for use in attaching the radiant barrier to roof rafters.

In yet another embodiment, the thermal radiant barrier ensures that air escaping around a roof baffle is guided along the underside of the roof decking.

In still another embodiment of the invention, the invention maintains the ventilating air at the temperature of the air outside the dwelling.

DRAWING FIGURES

These and other more detailed and specific features of the present invention are more fully disclosed in the following specification, reference being had to the accompanying drawings, in which:

FIG. 1 is a cross-sectional side view of a typical roofing system found in the prior art.

FIG. 2 is a view of typical roofing system found in the prior art from the perspective of inside the attic.

FIG. 3 is a perspective view of an exemplary thermal radiant barrier first portion of this invention;

FIG. 4 is a front perspective view of an exemplary thermal radiant barrier first portion of this invention in place under a roof of a structure.

FIG. 5 is a cross-sectional side view of a roofing system including the thermal radiant barrier first portion of the present invention in use.

FIG. 6 is a perspective view of an exemplary thermal radiant barrier second portion elongated planar portion.

FIG. 7 is a perspective view of an exemplary thermal radiant barrier first and second portion in hinged arrangement.

FIG. 8 is a cross-sectional side view of a roofing system including the thermal radiant barrier first portion and second portion in use.

FIG. 9 is an alternate embodiment of an exemplary thermal radiant barrier of this invention shown the thermal barrier walls at an obtuse angle.

FIG. 10 is an alternate embodiment of an exemplary thermal radiant barrier of this invention shown the thermal barrier walls at an acute angle.

FIG. 11 is another alternate embodiment of an exemplary thermal radiant barrier of this invention in arc-like formation.

DETAILED DESCRIPTION OF THE INVENTION

The present may be described with reference to a pitched roof structure, the invention is contemplated for use with any roofing structure having an attic space, such as for example trussed roofing structure. Indeed the present invention is described with reference to a roof decking. It is understood that in construction, the roof decking may underlie other roofing materials such as for example, shingles.

FIG. 3 is a perspective view of first embodiment of an exemplary thermal radiant barrier 200 according to the present invention. Thermal radiant barrier 200 comprises a first portion 210 having a rectangular shaped elongated planar base 202 of length l, width w and a thickness th. As noted, roof rafters are ordinarily regularly spaced a distance d_r apart one from the other. Width w is chosen to be less than distance d_r. Length l may be chosen to be less than the length of the rafters supporting a roof decking. For example, length l may be ¼ or ⅓ or ½ of the length of rafter 104. Alternatively, length l may be chosen to be substantially equal to the length of rafters 104.

Thermal radiant barrier 200 may be formed of rigid material. For example, thermal radian barrier 200 may be formed of a rigid board Styrofoam, formed cellulose, and the like. Since the R-value is a function of the material chosen and the thickness of the material, the thickness th may be chosen with considerations of the material chosen and the R-value desired. For example, for a Styrofoam such that the R-value of thermal radiant barrier 200 is the R-value predetermined for insulation according to the building code of a geographic region. The R-value of thermal radiant barrier 200 is determined from composition of the material used in the construction of the thermal barrier 200 using calculations known by those skilled in the art. [Verify this]

Thermal radiant barrier 200 is further includes sidewalls 204. Sidewalls 204 are joined projecting outwardly from planar base 202. Sidewalls 204 may be constructed of similar or same material as planar base 202 such that sidewalls 204 have an R-value equal or substantially equal to the R-value of planar base 202. In one exemplary embodiment, the angle Θ between planar base 202 and sidewalls 204 may be a substantially a right angle. As shown in the Figures, alternate of the first portion 210 embodiments of thermal radiant barrier 200, angle Θ may be obtuse (FIG. 8) or acute (FIG. 9). Further still, thermal radiant barrier 200 may be substantially arc shaped as shown in FIG. 10.

The first portion 210 of thermal barrier 200 may be composed of a single piece with planar base 202 and sidewalls 204 integrally formed. Alternatively, the planar base 202 and the sidewalls 204 may be constructed of separate pieced formed so as planar base 202 and sidewalls 204 may be joined or affixed together.

FIG. 4 is a front perspective view of an exemplary embodiment of a first portion 210 of thermal radiant barrier 200 of the present invention in use. FIG. 5 is a cross-sectional view of the first portion 210 of thermal radiant barrier 200 in use. As shown, first portion 210 of thermal radiant barrier 200 is positioned between rafters 104. First portion 210 of thermal radiant barrier 200 may further be positioned overlying an open end of soffit vent 112. Further still first portion 210 of thermal radiant barrier 200 is positioned in communication with the underside of decking 102. That is, first portion 210 of thermal radiant barrier 200 may be positioned against decking 102.

In one exemplary embodiment, first portion 210 includes means for affixing thermal radiant barrier 200 to the underside of decking 102. Exemplary means for affixing may include tabs 206 (or flanges) shown in FIG. 1. Tabs 206 may be made integral to the sidewalls 204. Tabs 206 may be made of any material suitable for permitting thermal radiant barrier 200 to be affixed to decking 102. Tabs 206 may be formed to permit a builder to affix the thermal radial barrier 200 using staples, nails or the like. Other affixing means may be substituted for or included with tabs 206. For example, the affixing means may include a suitable adhesive placed on an edge of the thermal radiant barrier 200 contacting decking 102 or rafters 104. In this way, thermal may be glued in position.

In use, first portion 210 of thermal radiant barrier 200 creates an air passageway (or chute) from soffitt vent 112. In some embodiments, first portion 210 of the thermal radiant barrier 200 may be used in place of, or along with baffle 120. In one embodiment, first portion 210 of thermal radiant barrier 200 may be positioned overlying baffle 120. In this position, first portion 210 of thermal radiant barrier 200 has the added advantage of ensuring that any air escaping around the baffle 120 is captured between the first portion 210 of thermal radiant barrier 200 and the underside of decking 102 and channeled to the underside of the decking 120.

As shown in FIGS. 4 and 5, the air passageway or air channel is formed between the decking 102 and the first portion 210 of thermal radiant barrier 200 such that outside air 114 entering soffit vent 112 is guided along the underside of decking 102. The outside air 114 is guided along the length l of the thermal radiant barrier 200 and exits the passageway to mix with the attic air 116. As the outside air 114 traverses from the soffit vent 112 to the attic area, the outside air 114 traverses alongside the underside of decking 102. Thermal radiant barrier 200 having a predetermined R-value chosen according to values outlined in the geographic area's the building code, insulates the outside air from the higher temperature t_a of the attic air 116. In this way, thermal radiant barrier ensures that the temperature of outside air 114 nearest the underside of the decking remains relatively unchanged at t_o. This provides an advantage over the prior art in that the temperature of the air nearest the underside of decking 102 is at or near the temperature of the outside air 114, such that the difference in temperature between the air nearest the underside of the decking 102 is at zero (t_o−t_o) or near zero. This temperature change eliminated or minimizes the thawing and freezing affect leading to ice dams.

Additionally, the thermal radiant barrier 200 at the soffit vent 112 is not compressed as is the insulation 118, since the thermal radiant barrier 200 is made of a rigid insulating material. Thus, the thermal radiant barrier 200 nearest the compressed insulation 118 will be prohibiting heat transference at the R-value of the thermal radiant barrier 200. Thus thermal radiant barrier 200 ensures the area near the compressed insulation 118 is kept at the R-value recommended for the geographic region.

FIG. 7 is a depiction of an alternate exemplary embodiment of thermal radiant barrier 200 having a second portion 260, shown in FIG. 6. Thermal radiant barrier second portion 260 has a substantially elongated and planar base 262. The second portion 260 may include a length l, width w, and a thickness th, where the length, width and thickness are equal to those same dimensions as the first portion of the thermal radiant barrier 210 depicted in FIG. 3. Second portion 260 is comprised of a rigid insulating material as is described with respect to thermal radiant barrier 200 depicted in FIG. 3, above. Alternatively, the dimensions of second portion 260 may be such that second portion 260 may be positioned between joist 106. In this instance, the width of second portion 260 may be substantially equal to the distance between regularly spaced joist 106.

FIG. 7 depicts the first and second portions of thermal radiant barrier 200 in hinged arrangement. First and second portions of thermal radiant barrier 200 may be joined at a first end of the first and second portions by a hinging means 264, such as for example, a hinge, hinging tape, strap hinge, paper metal or plastic joint, or the like capable of permitting the first portion 210 of thermal radiant barrier 200 to be folded onto second portion 260. In the hinged arrangement, the first portion 210 of the thermal radiant barrier 200 may be posited at an angle β relative to the second portion 260.

FIG. 8 shows the hinged arrangement depicted in FIG. 7 in use. As shown, the first portion 210 of thermal radiant barrier 200 is positioned as is described above in FIG. 4 and FIG. 5. Particularly, the first portion 210 of thermal radiant barrier 200 may be position overlying baffle 120 to channel outside air 114 along the underside of decking 102. Additionally, the first portion 210 of thermal radiant barrier 200 is hingedly affixed to the second portion 260. The first portion 210 of thermal radiant barrier 200 and the second portion 260 may be hinged at an angle β, where angle β is substantially equal to the angle drawn between the rafters 104 and joist 106.

The second portion 260 is positioned underlying at least portion of Batt insulation 118 and in proximity to baffle 120. In this arrangement, the compressed insulation 124 is positioned in proximity of hinge means 262. However, as noted, the second portion 262 has an R-value recommended by the building codes of the geographic area. In one embodiment the R-value of the second portion 262 is substantially equal to the R-value of the insulation 118. Since the second portion 262 is comprised of rigid insulation it does not compress. As such, the R-value at the compressed insulation 124 is no less that the R-value of second portion 262. Further, the second portion 260 may extend past the compressed insulation 124 to further ensure that the R-Value immediately past the compressed insulation 124 is at least the R-Value of the second portion 260.

An additional advantage of hinged arrangement in FIG. 7 is that the arrangement additionally assists in ensuring that the air transgressing from soffitt vent 112 to the baffle 120 is captured by the first portion 210 of the thermal radiant barrier 200 to be channeled along the underside of decking 102.

FIGS. 9-11 depict different embodiments of the first portion 210 of thermal radiant barrier 200. According to FIG. 9, angle Θ between planar base 202 and sidewalls 202 may be obtuse. In this way, the volume of outside air 114 transgressing through the air passageway is contacting a larger surface area of the underside of decking 102. One advantage of this embodiment is that a greater surface area of decking 102 may be kept at or near temperature t_o. FIG. 10 illustrates that angle Θ may be an acute angle. One advantage of this embodiment is that it may be fitted in a space between the rafters that are narrower that width w of the planar base 202. This embodiment including the acute angle Θ further permits a greater volume of outside air to transgress the air passageway.

Alternate embodiment in FIG. 11 illustrates that the overall shape of the first portion 210 of thermal radiant barrier 200 may be arc-shaped in cross-section. This embodiment is yet another embodiment for increasing the volume of outside air 114 transgressing near the underside of decking 102.

In all the embodiments shown, thermal radiant barrier 200 channels outside air alongside the underside of decking 102. The colder outside air temperature t_o is kept at or near the temperature it had when it entered the soffit vent 112.

Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. For example, although the invention is described with reference to pitched roofs, the invention is also suitable for trussed roofs of different shapes and arrangement. The invention is also applicable to shed roof shapes and any roof shape wherein ice dams may result. Additionally, the means for affixing the thermal radiant barrier may be any suitable means for affixing the barrier to the underside of the decking. Where tab like affixing means are used, the tab like affixing means may be multiple in number, or the tab may be a single tab positioned along the sidewalls of the invention. The fixing means may be integral to the sidewalls or made separate from the sidewalls. Therefore, the sprit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein, but includes equivalents thereof.

Further, even though a preferred embodiment of the invention has the first and second portions of the thermal radiant barrier to be composed of the same material, it is contemplated that the first portion and the second portion of the thermal radiant barrier may be comprised of differing materials. In this case, the thickness or the first portion and the thickness of the second portion may be different. It is understood that the thickness of the first or the second portion of the thermal radiant barrier may be chosen depending on the desired or recommended R-value of each portion.

Claims

1. A thermal radiant barrier for use against the underside of a roof decking in between two spaced rafters, said thermal radiant barrier comprising:

a. A thermal radiant barrier first portion including a substantially planar base, said substantially planar base substantially rectangular in shape; said thermal radiant barrier first portion planar base having a length l, a width w, and a thickness th, wherein the thickness th, is chosen in accordance with the material comprising the thermal radiant barrier such that said thermal radiant barrier first portion has a predetermined recommended attic insulation R-value for the geographic region,

b. a first sidewall projecting at an angle Θ from a first side of said planar base, a second sidewall projecting at said angle Θ from a second side of said planar base, said first and second sidewalls positioned opposite one from the other,

c. a means for affixing said first and second sidewalls to said underside of a roof decking, wherein said thermal radiant barrier forms an air passageway from a soffit vent, such that air is channeled from said soffit vent along the underside of said roof decking.

2. A thermal radiant barrier of claim 1, wherein said two spaced rafters are spaced apart by a distance dr, and wherein said width w, is substantially equal to said distance dr.

3. A thermal radiant barrier of claim 1, wherein said substantially planar base overlays a soffitt baffle for channeling said air from said soffitt vent along the underside of said roof decking.

4. A thermal radiant barrier of claim 1, further comprising a thermal radiant barrier second portion connected to said thermal radiant barrier first portion, said thermal radiant barrier second portion including a substantially planar base substantially rectangular in shape.

5. A thermal radiant barrier of claim 4, wherein said thermal radiant barrier first portion is connected to said thermal radiant barrier second portion by hingeable means.

6. A thermal radiant barrier of claim 5, wherein said thermal radiant barrier second portion planer base includes length, a width, and a thickness, wherein said thermal radiant barrier second portion length and width are substantially equal to said thermal radiant barrier first portion length and width.

7. A thermal radiant barrier of claim 6, wherein said thermal radiant barrier second portion thickness is chosen for thermal radiant barrier second portion to have a predetermined recommended attic insulation R-value for the geographic region.

8. A thermal radiant barrier of claim 7, wherein said thermal radiant barrier second portion underlies a compressed portion of an attic floor insulation.

9. A thermal radiant barrier of claim 8, wherein said compressed portion has an R-value less than recommended for attic floor insulation in the geographic area.

10. A thermal radiant barrier of claim 8, wherein said thermal radiant barrier second portion underlies a portion of attic floor insulation, where said thermal radiant barrier second portion underlies an uncompressed portion of said attic floor insulation.

11. A method for controlling the temperature of air on the underside of roof decking comprising:

providing a passageway for air entering an attic through a soffit vent, said passageway for channeling said air along the underside of said roof decking, and

wherein said passageway is formed of a material having an R-value recommended for attic insulation in the geographic region.

12. A method of claim 11 further comprising providing a material under a compressed portion of an attic floor insulation, wherein said material has an R-value recommended in the geographic region for attic floor insulation.