US20110201266A1

US20110201266A1 - Ventilated Roof Apparatus and Method

Info

Publication number: US20110201266A1
Application number: US13/021,942
Authority: US
Inventors: John C. Henderson
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-02-12
Filing date: 2011-02-07
Publication date: 2011-08-18

Abstract

In ventilating a roof, an eave vent and a ridge vent are provided. The eave vent and ridge vent each is equipped with a fabric filter. The fabric filter is not waterproof and is wettable and hence self-cleaning. The permeability to air of the eave vent fabric filter is less than that of the ridge vent fabric filter and the resistance to air flow of the eave vent is greater than that of the ridge vent. The attic space under the roof acts as a manifold, distributing low pressure throughout the attic space.

Description

I. RELATED APPLICATIONS

This application is related to and claims priority from provisional application No. 61/337,855 filed Feb. 12, 2010 by the inventor named herein.

II. BACKGROUND OF THE INVENTION

A. Field of the Invention
The Invention is an apparatus for ventilating a roof, a roof ventilated using the apparatus of the invention and a method of ventilating a roof using the apparatus.
B. Statement of the Related Art
Moisture trapped in an attic or other space underneath the pitched roof of a structure can damage the roof, can damage the remainder of the structure and can promote growth of mold within the attic. To avoid these effects, the space underneath the roof must be ventilated.
As used in this document, the term ‘attic’ refers to an attic and also refers to any other air space under a roof, such as the space between a ceiling or insulation and a roof deck of a structure equipped with a cathedral ceiling.
During daylight hours, the sun shining on the roof warms the roof deck, causing the roof deck to be warmer than the ambient air. The warm roof deck warms the air within the attic. During cold weather, heat within the inhabited space of the structure will leak into the attic space, which also warms the air in the attic space. The warm air within the attic space expands, becomes buoyant, and tends to rise. Because the roof is pitched, the warm air rises toward the ridge of the roof. The warm air can be released from the ridge by a ridge vent.
Warmed air escaping from the vent will place the attic space at a lower air pressure than the ambient pressure outside the attic. For effective ventilation, eave vents are provided to allow make-up ambient air to enter the area under the roof. If any portion of the roof is starved for ventilation air, then the lack of air flow through the air-starved attic space may allow the evils of inadequate ventilation to occur.
A roof equipped with eave and ridge vents acts as a large, low-pressure air pump, pumping air out through the ridge vent and in through the eave vents. The power input to the roof air pump system is heat energy generated either by sunlight shining on the roof deck or by heat leaking into the attic from the heated living space of the structure.
The ridge and eave vents must provide both an avenue for escape and entry of the air and also must prevent the entry of moisture in the form of rain or snow into the attic space. To that end, a ridge vent or an eave vent may feature a fabric filter. The prior art fabric filter generally is selected to be water proof and to prevent rain or snow from entering the vent while allowing air to pass through the fabric.
Because the flow of air through the attic is generally from the eave vent to the ridge vent, dust or dirt in the air moving through the attic can be trapped on the side of the fabric filter of the ridge vent that is toward the attic. The result is that the ridge vent can become blinded over time.
Blinding of the fabric filter is less of an issue for an eave vent, since dust and dirt will tend to collect on the side of the fabric filter that is toward the outside of the structure. Provided that the fabric filter is located so as to expose the fabric filter to the weather, rain water may wash the dust and dirt from the fabric filter of the eave vent, preventing the fabric filter from becoming blinded.
The present invention is not taught by the prior art.

III. SUMMARY OF THE INVENTION

The invention is an apparatus for ventilating an attic or other area under a roof. The invention also is a roof ventilated using the apparatus and a method of ventilating a roof. The apparatus is a ridge vent, an eave vent, and a combination of the ridge and eave vents. The ridge vent may be a two-sided ridge vent.
As used in this document, the term ‘eave’ generally means the horizontal roof edge of a pitched roof. The ‘eave’ is generally the lowest location on a pitched roof deck. As used in this document, the term ‘eave vent’ includes a vent in a soffit located below a roof deck and also includes a top vent communicating through the top side of the roof deck from above. The ‘eave vent’ generally is located proximal to the eave, but in the case of the top vent may be located anywhere on the roof below the ridge vent.
As used in this document, the term ‘ridge’ means the locations on a pitched roof defined by intersecting planes of the roof deck and that define an included angle of less than 180 degrees. The ‘ridge’ generally is the highest location on the roof, unless the roof utilizes the hip roof design, in which event the ‘ridge’ may slope from the peak of the roof to the eave. As used in this document, a ‘ridge vent’ is located proximal to the ridge, including the sloping ridges of a hip roof.
A primary goal of any roof ventilation system is to provide ventilation to the attic or other entire area under the roof. As noted above, if flow paths through a portion of an attic do not exist, that portion of the attic will not be ventilated. If flow paths exist, but if other flow paths present inadequate resistance to air flow, the air will take the flow path of low resistance. The remainder of the roof that has a higher resistance to air flow will be starved for ventilation air and will suffer the evils associated with inadequate ventilation, as described above.
The apparatus, method and roof of the invention achieve more even ventilation of the attic space by adjusting the air flow resistance of the eave and ridge vents. The resistance to air flow is adjusted so that the resistance to air flow presented by the sum of the ridge vents is less than the resistance to air flow presented by the sum of the eave vents supplying the ridge vents. The entire attic space therefore operates at a negative pressure when the air in the attic is warmed, which negative pressure no one region of the eave vents can relieve. The volume of the attic therefore acts as a large manifold, conveying that negative air pressure to every corner of the attic.
Eave vents are provided in all areas of the roof, providing paths for ambient air to enter the attic. The resistance to air flow of the eave vents is selected to allow entry of ventilation air but not to allow so much air to enter that the negative pressure under the roof is relieved at any location. The resistance to air flow of the eave vents is selected to be substantially greater than the resistance to air flow of the ridge vent because, for a pitched roof, the length of the eaves for a roof generally is considerably greater than the length of the ridge. The length of the eave vents therefore generally is much greater than the ridge vents.
Both the ridge vent and the eave vent are composed of a corrugated plastic. The corrugations of the plastic define multiple elongated channels through which air passes.
The eave vent features an eave vent intake opening defined by the open ends of the multiple elongated channels that are exposed to the air outside the roof. The eave vent also features an eave vent discharge opening exposed to the air in the attic through a roof deck vent opening proximal to the eave.
The ridge vent features a ridge vent discharge opening that is exposed to the air outside the attic and defined by the open ends of the multiple elongated channels. The ridge vent also features a ridge vent intake opening communicating through the roof deck at a roof deck ridge opening proximal to the ridge. The discharge opening of the ridge vent and the intake opening of the eave vent are defined by the open ends of the multiple elongated channels defined by the corrugated plastic.
A fabric filter covers the discharge opening of the ridge vent and the intake opening of the eave vent. The fabric filter is composed of a fabric that wraps about each of the soffit and the ridge vent and is attached to both the top and the bottom of the soffit and of the ridge vent. Any suitable attachment means may be utilized, such as an adhesive bond or a thermal weld.
The fabric of the fabric filter is selected to allow water to pass through the fabric. The fabric is wettable and allows moisture to wick through the fabric and to wet both sides of the fabric, while preventing substantially all droplets of water from traveling through the fabric. Water that has passed through the fabric moves by gravity from the top to the bottom of the fabric. In so doing, the water entrains and carries off dust collected on both the inside and outside surfaces of the fabric. The fabric therefore allows the water to wash the dust from both the inside and the outside surfaces of the fabric, preventing blinding of the fabric filter.
Location of the fabric filter on the outside of the channels defined by the corrugated plastic prevents water that passes through the fabric from entering the attic space. Because the fabric filter is located at the outside end of the elongated channels defined by the corrugated plastic, any water passing through the fabric must travel the length of the elongated channels to reach the attic. Because the roof is pitched and because the elongated channels also are pitched to conform to the roof deck, that water is required to run up hill. Water penetrating the wettable fabric therefore does not enter the attic.
Attachment of the fabric filter to both the top side and the bottom side of the ridge vent or eave vent allows convenient handling and installation of the fabric filter. Installation of the ridge or eave vent involves nailing through the vent from the top side to the bottom side. Some of the nails penetrate the fabric that is wrapped about the top side and the bottom side of the vent, mechanically securing the two ends of the fabric to the roof. The mechanical connection of the fabric to the roof allows the fabric to withstand high winds without failure.
The resistance to air flow of the ridge vent and the eave vent is determined by the friction of air passing through the channels and by the air permeability of the fabric filter for each of the eave vent and the ridge vent. The dimensions of the eave vent and the ridge vent, and hence the friction of the air passing through the channels, are constrained by practical and aesthetic considerations. Those considerations include that the channels cannot be so large as to allow rain or snow to enter the attic space and cannot be so small as to easily blocked, as by leaves and debris. The aesthetic considerations include the appearance of the vent on the roof. The dimensions of the channels therefore do not allow extensive adjustment of the resistance to air flow of the vents.
Nonetheless, resistance to air flow can be readily adjusted by selecting a fabric filter having an appropriate permeability to air; namely, the resistance to air flow per unit area of the fabric. Selecting a fabric filter for the eave vent that has a low permeability relative to that of the ridge vent allows the air pressure within the attic to remain adequately low so that the attic acts as a manifold, drawing ventilation air through all of the eave vents and while providing adequate ventilation to the entire attic space.
The apparatus, method and roof of the invention provide that the fabric filter of the eave vents is selected so that the permeability of the soffit filter fabric is less than the permeability of the ridge vent filter fabric.
The apparatus, method and roof of the invention is particularly useful for ventilating roofs that previously have been difficult to ventilate without excess water penetration, such as hip roofs.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross section of a ventilated roof.

FIG. 2 is a schematic representation of air flow through the roof.

FIG. 3 is a cross section of a ridge vent in place on the roof deck.

FIG. 4 is a perspective view of the ridge vent of FIG. 3.

FIG. 5 is a cross section of an eave vent in place on a roof deck.

FIG. 6 is a perspective view of the eave vent of FIG. 5.

FIG. 7 is a perspective view of a roof deck.

FIG. 8 is a perspective view of the roof deck with an eave vent in place.

FIG. 9 is a perspective view of the roof deck in the process of installing shingles and the ridge vent.

FIG. 10 is a perspective view of the completed roof.

V. DESCRIPTION OF AN EMBODIMENT

The invention is an apparatus and method for ventilating an attic space or other area under a roof. As illustrated by FIGS. 1 and 7 through 10, a roof deck 2 covers a structure 4. The structure 4 features an attic space 6 beneath the roof deck 2. As used in this document, the term ‘attic space’ also includes any area under a roof, such as the space between the ceiling and a roof deck 2 of a room having a cathedral ceiling. The roof deck 2 is pitched as illustrated by FIGS. 1 and 7 through 10, meaning that the roof deck 2 defines an adequate angle with the horizontal to allow the use of shingles 12. The roof deck 2 is composed of any suitable planar material, such as plywood or metal sheets. The roof deck 2 defines a ridge 8 at its highest location and an eave 10 at a location lower than the ridge 8.
As illustrated by FIGS. 1, 3, 4, 9 and 10, the roof includes a ridge vent 14 covering a roof deck ridge vent opening 16 located at the ridge 8 of the roof deck 2. The roof also includes an eave vent 18 covering a roof deck eave vent opening 20 located proximal to the eave 10. The eave vent 18 and roof deck eave vent opening 20 may be at any location on the roof deck 2 below the elevation of the ridge 8 and ridge vent 14.
The eave vents 18 illustrated by the drawings are of the top vent type and communicate with the attic space 6 through the eave vent opening 20 from above the roof deck 2. This description of an embodiment applies equally to an eave vent 18 of the soffit vent type that communicates with the attic space 6 through the soffit from below the roof deck 2.
As shown by FIG. 1, air 22 within the attic space 6 is warmed by the sun shining on the roof deck 2 or by heat from the inhabited space of the structure 4. The air 22 expands due to the increased temperature. The warmed air 22 is more buoyant than other air 22 within the attic space 6 and rises within the attic space 6 until the air reaches the ridge 8. The warmed air 22 flows through the ridge vent opening 16 and through the ridge vent 14. Make-up air 22 flows from outside the attic space 6 through the eave vent 18 and through the roof deck eave vent opening 20 into the attic space 6. The ventilated roof, including the eave vent 18, the eave vent opening 20, the attic space 6, the roof deck 2, the ridge vent opening 16 and the ridge vent 14 comprises a heat-powered air pump, pumping air 22 out through the ridge vent 14 and in through the eave vent 18.
FIG. 2 is a schematic diagram illustrates the air pressure and flow relationships of the ventilated roof. Heated air 22 flows out of the attic space 6 through ridge vent 14 due to the buoyancy of the heated air 22. The departure of the heated air 22 through the ridge vent 14 reduces the air pressure within the attic space 6. The reduced air pressure within the attic space 6 causes cool make-up air 22 to flow through the eave vents 18 due to the higher air pressure outside the attic space 6. The cool air 22 is warmed within the attic space 6, becomes buoyant and rises to the ridge vent 14, repeating the process.
All areas of the roof are equipped with eave vents 18, as indicated by the four schematic eave vents 18 of FIG. 2. The flow of air 22 at any one location on an eave vent 18 is determined by the air pressure differential across the eave vent 18 and coupled with the resistance to air flow presented by the eave vent 18. The air pressure differential across a portion of an eave vent 18 is determined by factors that include the buoyancy of the air 22 exiting the ridge vent 14, whether the portion of the roof deck 2 above the eave vent is subject to direct sunlight, the resistance of all of the other portions of eave vent and the length of the flow path from the eave vent 18 to the ridge vent 14.
Air 22 flowing into the attic space 6 will follow the path of least resistance. If one (or more) of the eave vents 18 presents an adequately low resistance to air flow coupled with a short flow path while other eave vents 18 present a higher resistance to air flow coupled with a longer flow path, the portions of the eave vents 18 with very low resistance and hence a relatively high air flow may relieve the pressure difference between the inside and outside of the attic space 6. The portions of the attic space 6 served by the eave vent 18 having a higher resistance and a longer flow path then will see little, if any, airflow. Portions of the attic space 6 then are starved of ventilation air 22 and may suffer from all of the ill effects of inadequate ventilation.
The airflow can be more evenly distributed among the eave vents 18, assuring more even ventilation of all areas of the roof, if the resistance to airflow of each eave vent 18 is adequately high so that the attic space 6 acts as a manifold, distributing the relatively low pressure to all areas of the attic space 6.
FIGS. 3 through 6 illustrate construction of the ridge vent 14 and the eave vent 18 to achieve more even distribution of ventilation air 22 within the attic space 6. FIG. 3 is a cross section of a ridge vent 14 installed on a roof deck 2. Roof deck 2 defines a pitched roof and is clad with shingles 12. Ridge vent 14 is composed of corrugated plastic panels 28. Each corrugated plastic panel 28 comprises two planar plastic layers with a corrugated plastic layer in between, similar in appearance to familiar corrugated cardboard. The corrugated plastic 28 panels define a plurality of channels 30. The plurality of channels communicate between a ridge vent opening 24, also referred to herein as the ‘ridge vent discharge opening 24,’ that is in contact with air 22 outside of the ridge vent 14 and a ridge vent intake opening 31 on the underside 32 of the ridge vent 14. The ridge vent intake opening 31 is in communication with the roof deck ridge vent opening 16, which is in communication with the air 22 within the attic space 6.
The ridge vent opening 24 is equipped with a ridge vent fabric filter 34 that covers the ridge vent opening 24. As shown by the detail cutaway drawing of FIG. 4, the ridge vent fabric filter 34 is wrapped about the top 36 and the bottom 38 of the ridge vent 14 and secured to the top 36 and bottom 38 of the ridge vent 14 by an adhesive bond or by thermal welding.
As shown by FIG. 3, wrapping of the fabric filter 34 about the top 36 and bottom 38 of the ridge vent 14 allows the fabric filter 34 to be secured to ridge vent 14 and to the roof deck 2 by nails 40 when the ridge vent 14 and shingles 12 are installed.
The size of ridge vent opening 24, and hence the area of the ridge vent available to allow heated air 22 to escape, is constrained by aesthetic considerations of the appearance of the finished roof. Three layers of corrugated plastic panels 28, totaling about three quarters of an inch in thickness, has proven acceptable in practice.
The construction of the eave vent 18 is illustrated by FIGS. 5 and 6. The eave vent 18 also is composed of corrugated plastic panels 28 defining a plurality of eave vent channels 30. The channels communicate between an eave vent opening 26, also referred to herein as the ‘eave vent intake opening 26,’ and an eave vent discharge opening 50 on the eave vent bottom 48. The eave vent opening 26 is on the outside of the eave vent and in contact with air 22 outside the attic space 6. The eave vent discharge opening 50 is in communication with a roof deck eave vent opening 20 that communicates through the roof deck 2 to the attic space 6. The thickness of the eave vent opening 26 is driven in part by aesthetic considerations and in part by resistance to moisture penetration. Three layers of corrugated plastic panels 28, totaling about three quarters of an inch in thickness, have proven suitable in practice.
The eave vent 18 is wedge-shaped. To maintain the wedge-shape while allowing ventilation air 22 to move through the eave vent 18, an eave vent support 42 intermediate between the eave vent opening 26 and the roof deck eave vent opening 20 is provided. The eave vent support 42 is composed of a second plurality of layers of corrugated plastic panels 28. The number of panels 28 making up the eave vent support 42 is less than the number of panels making up the eave vent opening 26 to allow the eave vent 18 to be wedge-shaped when installed on a roof deck 2. A thickness of two corrugated plastic panels 28 have proven suitable in practice for the eave vent support 42.
An eave vent fabric filter 44 covers the eave vent opening 26. The eave vent filter fabric 44 is wrapped about the eave vent top 46 and the eave vent bottom 48. The wrapping of the eave vent fabric filter 44 about the top 46 and bottom 48 provide that nails 40 will secure the filter fabric 44 to the eave vent 18 and the eave vent 18 to the roof deck 2 when the eave vent 18 is installed.
The ridge vent fabric filter 34 and the eave vent fabric filter 44 each has a permeability to air flow. The resistance of the ridge vent 14 and the eave vent 18 to the passage of air 22 is a function of the size (thickness and length) of the ridge vent opening 24, the friction of the air 22 moving through the channels 30 of the ridge 14 and soffit 18 vents and the permeability to air flow of the ridge vent fabric filter 34 and the permeability to air flow of the eave vent fabric filter 44. The less permeable the fabric filters 34, 44, the higher the resistance to air flow and the less air 22 that can flow through the vent 14, 18 for a given air pressure differential.
The resistances to air flow of the ridge vent 14 and the eave vent 18 therefore can be selected by selecting appropriate fabric filters 34, 44. The fabric filters 34, 44 are selected so that the permeability of the eave vent fabric filter 44 is less than the permeability of the ridge vent fabric filter 34. For ridge and eave vents 14, 18 having approximately the same total area for the eave vent opening 26 and the ridge vent opening 24, selecting fabric filters 34, 44 when the permeability of the eave vent fabric filter 44 is less than that of the ridge vent fabric filter 24 provides that the entire attic space 6 is maintained at a reduced air pressure when the ventilation system is in operation to ventilate the roof and provides that no portion of the attic space 6 is starved for ventilation air. In short, the entire attic space 6 acts as a manifold and distributes the reduced air pressure to all of the eave vents 18.
The fabric filter 34, 44 is selected to be wettable for the purposes of washing accumulated dust from otherwise inaccessible fabric filter 34, 44 surfaces. The wettable fabric selected for the fabric filters 34, 44 is not waterproof and allows water from rain or snow to move through the fabric filters 34, 44 from the outside of the ridge and eave vent openings 24, 26. The water runs down the inside surfaces of the fabric filters 34, 44 due to gravity, rinsing accumulated dust from the fabric filters 34, 44. The use of a non-waterproof, wettable fabric for fabric filters 34, 44 allows both sides of the fabric filters 34, 44 to be cleaned by water from rain or snow. The water is prevented from entering the attic space 6 or from otherwise entering the structure 4 by the uphill journey through the multiple channels 30 that the water would have to travel to reach the attic space 6 (see FIGS. 3 and 6).
The wettable fabric that has proven successful in practice is Colback® TD series by Colbond, Inc., P.O. Box 1057, Enka, N.C. 28728. Colbond, Inc is a division of Low & Bonar PLC, a publicly traded UK corporation domiciled in Scotland. The Colback® fabric is a spunlaid, nonwoven fabric made from bicomponent filaments having a polyester core and a nylon 6 skin. The fibers are thermally bonded to form the fabric. The permeability to air of the fabric varies as does the weight of the fabric. The applicant believes that a fabric having a weight of 100 grams per square meter is suitable for the fabric filter 44 covering the eave vent opening 26. The applicant believes that a fabric having a weight of 30 to 50 grams per square meter is suitable for the fabric filter 34 covering the ridge vent opening 24. The fabric is selected to be black or dark gray in color for maximum heat absorption and to aesthetically blend in with the appearance of the roof.
FIGS. 7 through 10 illustrate installation of the apparatus of the invention. FIG. 7 is a roof deck 2 of a structure 4, such as a building. The roof deck 2 has a top side 52 and includes an eave 10 and a ridge 8. The roof deck also includes a roof deck eave vent opening 20 proximal to the eave 10 and a roof deck ridge opening 16 proximal to the ridge 8. The roof deck 2 is pitched.
FIG. 8 illustrates location of the eave vent 18 on the roof deck 2. The eave vent 18 is located proximal to the eave 10 and is located so that the eave vent discharge opening 50 is in communication with the roof deck eave vent opening 20. An end cap 54 tapers the eave vent 18 to the roof deck 2 and prevents breakage of shingles 12.
FIG. 9 illustrates the relative location of the eave vent 18, shingles 12, roof deck 2 and ridge vent 14. In FIG. 9, the eave vent 18, shingles 12 and ridge vent 14 are in the process of being installed. The shingles 12 cover the eave vent 18 and end cap 54. The ridge vent 14 overlays the top course of shingles 12 and covers the roof deck ridge vent opening 16 so that the ridge vent opening 24 on the outside of the ridge vent 14 is in communication through the ridge vent 14 to the roof deck ridge vent opening 16. The ridge vent 14 is two-sided, in that ridge vent openings 24 appear on both sides of the ridge 8. Ridge vent fabric filter 34 wraps about the ridge vent 14 and covers ridge vent opening 24.
FIG. 10 illustrates the roof with eave vents 18, ridge vent 14 and shingles 12 installed. Eave vent 18 is flanked by end caps 54 and covered by shingles 12. Eave vent opening 26, covered by eave vent fabric filter 44, is exposed to air 22 outside the attic space 6 of structure 4. The roof deck 2 is covered by shingles 12. The roof deck ridge vent opening 16 is covered by ridge vent 14. Ridge vent 14 also is covered by shingles 12. Ridge vent opening 24 is covered by ridge vent fabric filter 34 and is exposed to the air 22 outside the attic space 6. Air 22 enters the attic space 6 through the eave vent opening 26, passes through the attic space 6 and exits the attic space through the ridge vent opening 24. The flow of air is controlled by selecting the eave vent fabric filter 44 and the ridge vent fabric filter 34 so that the permeability to air of the eave vent fabric filter 44 is less than that of the ridge vent fabric filter 34. The resistance to air flow of the eave vent 18 therefore is greater than the resistance to air flow of the ridge vent 14.

LIST OF NUMBERED ELEMENTS

The following are indicated as numbered elements on the drawings.

a roof deck 2
a structure 4
an attic space 6
a ridge 8
an eave 10
shingles 12
a ridge vent 14
a roof deck ridge vent opening 16
an eave vent 18
a roof deck eave vent opening 20
air 22
A ridge vent opening 24
An eave vent opening 26
a corrugated plastic 28
a plurality of channels 30
a ridge vent discharge opening 31
an underside of the ridge vent 32
a ridge vent fabric filter 34
a top of the ridge vent 36
a bottom of the ridge vent 38
a nail 40
an eave vent support 42
an eave vent fabric filter 44
an eave vent top 46
an eave vent bottom 48
an eave vent discharge opening 50
a roof deck top side 52
an end cap 54

Claims

1. An apparatus, the apparatus comprising:

a. a roof deck, said roof deck being located on a structure, said roof deck covering an attic space, said roof deck being pitched, said roof deck having a ridge and an eave;

b. a ridge vent located proximal to said ridge, said ridge vent defining a ridge vent opening, said ridge vent opening being in communication with said attic space through said roof deck;

c. an eave vent, said eave vent being located at said eave, said eave vent defining an eave vent opening, said eave vent opening being in communication with said attic space through said roof deck, said ridge vent defining a ridge vent resistance to an air flow, said eave vent defining an eave vent resistance to said air flow, said eave vent resistance to said air flow being greater than said ridge vent resistance to said air flow.

2. The apparatus of claim 1 wherein said ridge vent and said eave vent are composed of a corrugated plastic, said corrugated plastic defining a plurality of channels, said plurality of channels of said ridge vent defining said ridge vent opening, said plurality of channels of said eave vent defining said eave vent opening.

3. The apparatus of claim 2, further comprising:

a. a ridge vent fabric filter, said ridge vent opening being disposed on an outside of said ridge vent, said ridge vent fabric filter covering said ridge vent opening, said ridge vent fabric filter having a ridge vent fabric permeability to air;

b. an eave vent fabric filter, said eave vent opening being disposed on an outside of said eave vent, said eave vent fabric filter covering said eave vent opening, said eave vent fabric filter having an eave vent fabric permeability to air, said eave vent permeability to air being less than said ridge vent permeability to air.

4. The apparatus of claim 3 wherein said ridge vent fabric filter is composed of a wettable fabric.

5. The apparatus of claim 4 wherein said ridge vent defining a ridge vent top and a ridge vent bottom, said ridge vent fabric filter extending from said ridge vent top to said ridge vent bottom, said ridge vent fabric filter being secured to said ridge vent top and to said ridge vent bottom by a one of an adhesive bond and a thermal weld, said eave vent defining an eave vent top and an eave vent bottom, said eave vent fabric filter extending from said eave vent top to said eave vent bottom, said eave vent fabric filter being secured to said eave vent top and to said eave vent bottom by a one of said adhesive bond and said thermal weld.

6. The apparatus of claim 5 wherein said eave vent opening is composed of a first plurality of layers of said corrugated plastic, said eave vent defining an eave vent support, said eave vent support being composed of a second plurality of layers of said corrugated plastic, said first plurality being greater than said second plurality, said corrugated plastic of said eave vent support defining a plurality of said channels, said eave vent opening being in communication with said attic space through said channels defined by said eave vent support.

7. An eave vent apparatus, the eave vent apparatus comprising: a corrugated plastic, said corrugated plastic defining a plurality of channels, said plurality of channels defining an eave vent intake opening, said eave vent having a bottom side, said bottom side of said eave vent opening defining an eave vent discharge opening, said eave vent intake opening being in communication with said eave vent discharge opening, said eave vent being configured so that said plurality of channels defining said eave vent intake opening are in communication with an attic space when said eave vent is mounted to a top side of a roof deck having a ridge and an eave and said eave vent discharge opening is in communication with a roof deck eave vent opening proximal to said eave, said eave vent having an eave vent resistance to air flow, said eave vent resistance to air flow being selected so that said eave vent resistance to said air flow is greater than a ridge vent resistance to said air flow when said eave vent is mounted in communication with said roof deck eave vent opening and said ridge vent is mounted in communication with a roof deck ridge opening proximal to said ridge.

8. The apparatus of claim 7, the apparatus further comprising:

A soffit fabric filter, said eave vent opening being disposed on an outside of said eave vent, said eave vent fabric filter covering said eave vent opening, said eave vent fabric filter having an eave vent fabric permeability to air, said eave vent permeability to air being less than a permeability to air of a ridge vent fabric filter when said eave vent is mounted in communication with said roof deck eave vent opening and said ridge vent is mounted in communication with said roof deck ridge opening, and said ridge vent has a discharge opening covered by said ridge vent fabric filter.

9. The apparatus of claim 8 wherein said eave vent fabric filter is composed of a wettable fabric.

10. A ridge vent apparatus, the ridge vent apparatus comprising: a corrugated plastic, said corrugated plastic defining a plurality of channels, said plurality of channels defining a ridge vent discharge opening, the ridge vent apparatus having a bottom side, said bottom side of the ridge vent apparatus defining a ridge vent intake opening, said ridge vent intake opening being in communication with said ridge vent discharge opening, said ridge vent intake opening being in communication with an attic space when said ridge vent is mounted to a ridge of a roof deck and said ridge vent intake opening is in communication with a roof deck ridge opening in said roof deck, said ridge vent having a ridge vent resistance to air flow, said ridge vent resistance to air flow being selected so that said ridge vent resistance to said air flow is less than an eave vent resistance to said air flow when said ridge vent is mounted to said roof ridge and said eave vent is mounted in communication with said attic space proximal to an eave of said roof deck.

11. The apparatus of claim 10, the apparatus further comprising:

A ridge vent fabric filter, said ridge vent discharge opening being disposed on an outside of the ridge vent apparatus, said ridge vent fabric filter covering said ridge vent discharge opening, said ridge vent fabric filter having a ridge vent fabric permeability to air, said ridge vent permeability to air being greater than a permeability to air of an eave vent fabric filter when said ridge vent is mounted to said ridge of said roof deck, and said eave vent is mounted in communication with said attic space proximal to said eave, and said eave vent has an intake opening covered by said eave vent fabric filter.

12. The apparatus of claim 11 wherein said ridge vent fabric filter is composed of a wettable fabric.

13. A method for ventilating a roof, the method comprising:

a. providing a ridge vent, said ridge vent being composed of a corrugated plastic, said corrugations defining a plurality of ridge vent channels, said plurality of ridge vent channels defining a ridge vent discharge opening, said bottom of said ridge vent defining a ridge vent intake opening, said ridge vent having a resistance to air flow from said ridge vent intake opening to said ridge vent discharge opening;

b. installing said ridge vent, the roof defining a roof deck having a ridge and an eave and defining an attic space, said roof defining a roof deck ridge opening proximal to said ridge, said roof deck ridge opening communicating through said roof deck, said ridge vent being installed so that said ridge vent intake opening is located in communication with said attic space through said roof deck ridge opening;

c. providing an eave vent, said eave vent being composed of said corrugated plastic, said corrugated plastic defining a plurality of eave vent channels, said plurality of eave vent channels defining an eave vent intake opening, said eave vent having a bottom side, said eave vent bottom side defining an eave vent discharge opening, said eave vent intake opening being in communication with said eave vent discharge opening, said eave vent having an eave vent resistance to air flow from said eave vent intake opening to said eave vent discharge opening, said eave vent resistance to air flow being greater than said ridge vent resistance to air flow; and

d. installing said eave vent proximal to said eave of said roof deck, said eave vent discharge opening being in communication with said attic space.

14. The method of claim 13 wherein said ridge vent includes a ridge vent fabric filter, said ridge vent fabric filter being configured to cover an outside of said ridge vent discharge opening, said ridge vent fabric filter having a ridge vent permeability to air, said eave vent including an eave vent fabric filter, said eave vent fabric filter being configured to cover an outside of said eave vent intake opening, said eave vent fabric filter having an eave vent permeability to air, said ridge vent permeability to air being greater than said eave vent permeability to air.

15. The method of claim 14 wherein said ridge vent has a ridge vent top side, said ridge vent fabric filter extending from said ridge vent top side to said ridge vent bottom side, said ridge vent fabric filter being attached to said ridge vent top side and to said ridge vent bottom side by a one of an adhesive bond and a thermal weld, and wherein said eave vent has an eave vent top side, said eave vent fabric filter extending from said eave vent top side to said eave vent bottom side, said eave vent fabric filter being attached to said eave vent top side and to said eave vent bottom side by said one of said adhesive bond and said thermal weld.

16. The method of claim 15 wherein said ridge vent fabric filter and said eave vent fabric filter are composed of a wettable fabric.

17. The method of claim 16 wherein said ridge and said eave of said roof each has a length, said ridge vent has a length and said eave vent has a length, said length of said ridge vent is selected to occupy substantially all of said length of said ridge, said length of said eave vent is selected to occupy substantially all of said length of said eave.