Roof Construction Providing Air Flow From Eave To Ridge

Abstract

A roof construction designed to provide air flow along the underside of the roof deck from the facia to the ridge to thereby prevent the formation of ice dams on the roof in the winter as well as removing accumulated attic heat for summer comfort. The facia is attached to the ends of the rafters and is a dual-wall member including a front facia board and a backing member which are spaced apart to provide a series of vertically extending passages therebetween. The upper end of the backing member terminates short of the upper end of the facia board so that air flowing upwardly within the passages is directed along the underside of the roof deck and flows upwardly along the roof deck to an outlet at the ridge of the roof. Baffles are located within the spaces between adjacent rafters to insure that air flow along the underside of the roof deck is unobstructed. The baffles extend from the area of the facia to a location inwardly of the top plate on the exterior wall of the building. This application is a continuation-in-part of application Ser. No. 745,298, filed July 16, 1968, entitled Roof Construction and now abandoned.

Description

This invention relates to a roof construction designed to provide air flow along the under surface of the roof deck from the facia to the ridge to prevent formation of ice dams on the roof in winter, and to remove attic heat for summer comfort.

In northern climates, where snow accumulates and where temperatures are below freezing during at least a part of the period when snow is accumulated on the roof, up roof snow melting will be normally accompanied by ice formations at the eaves or overhang of the roof. These ice formations act as dams to retain subsequent melted snow and the melted snow or water will thereby flow under, down and along the roofing, sheathing and structural members of the building which are not normally designed for water attack on the underside of the roof deck. Water damage resulting from melted snow seepage into cornices and sidewalls is a wide-spread problem in northern climates and can result in stain or blistered paint, as well as cracked stone, brick or stucco. In addition, water leakage caused by the ice formations or dams at the eaves also causes effluoroscence on masonry and plastered surface.

The cause of ice formations or ice packs at the eaves is a result of the melting snow on the upper portion of the roof and the melted snow flows downwardly to the area of the eaves, where the attic heat is no longer present to assist melting. A thermal drop is present at the area of the eaves and beyond, so that melted snow freezes into ice packs at a location beyond the walls of the building. The ice packs so formed block further run-off and act as dams so that subsequent melted snow that flows downwardly seeps under the shingles and through the nail holes or sheathing cracks. In many cases the dammed melted snow will run downwardly along the sheathing and rafters to the soffit board where it will accumulate on the soffit, In other instances, the melted water will run downwardly along the outer wall of the building to cause defects in painting as well as discoloration of the walls.

The formation of ice packs at the eaves can be prevented by eliminating the thermal gradient from the eaves to the ridge of the roof. The thermal gradient exists because of escaping heat from the living area beneath the roof which acts to heat the portion of the roof located above the living area, while the portion of the roof above the eaves is not so heated. An insulated ceiling will slow, but will not stop, heat from rising and accumulating in the space beneath the roof deck. Thus a thermal gradient exists on almost all roofs and even well insulated ceilings will not prevent the formation of thermal gradients along the roof which results in the formation of ice packs.

In the past, various methods have been employed for ventilating the attic area beneath the roof deck, but these ventilating methods have been designed primarily to remove accumulations of heat for summer comfort. In most cases these efforts have taken the form of louvers in the facia board or louvers or openings in the soffit which permit air to flow upwardly into the attic space. However, most prior art designs have been directed to the removal of accumulated attic heat in warm weather for summer comfort as well as trying to conserve the attic heat in winter to assist the cold weather heating efficiency. This equivocal position generally explains the reasons for the inadequate ventilation achieved by the prior art methods, which have been totally unsatisfactory in attempting to cope with the formation of ice packs at the eave area.

As a further problem in the prior art designs using a ventilated soffit, blasts of wind through the soffit openings occasionally build up velocities that will whip up the insulation located between the ceiling joists and thereby expose an area of the ceiling to the elements. This condition results in condensation with subsequent melting and water stain on the portion of the ceiling exposed to the elements.

In other situations when using a conventional vented soffit, the blast of wind will occasionally pass into the ends of the batts of insulation and again a cold ceiling, subject to the adverse condition of condensate accumulation, will exist in the ceiling corners of the outside walls of the building.

The present invention is directed to a roof construction designed to provide air flow along the underside of the roof deck from the facia board to the ridge of the roof, to thereby prevent the formation of ice dams on the roof in winter as well as removing accumulated attic heat for summer comfort. According to the invention, a facia is attached to the ends of the rafters and is a dual wall member including a front facia board and a backing member which is spaced from the facia board to provide a series of vertically extending passages therebetween. The upper end of the backing member terminates short of the upper end of the facia board so that air flowing upwardly within the passages is directed along the under surface of the roof deck and flows upwardly along the roof deck to an outlet at the ridge of the roof.

With the air flow produced by the roof construction of the invention, there is no appreciable thermal gradient from the ridge of the roof down to the eaves. With the elimination of the thermal gradient, ice packs will not be formed on the roof and thus, no water will be dammed to seep into and along the walls of the building.

Not only does the roof construction of the invention act to prevent the formation of ice dams in winter but the air flow acts to remove vapor as well as accumulated heat in the attic space in warm weather and this makes the dwelling more comfortable and eliminates the need for attic fans or the like.

The facia containing the vertical air passages can be applied to both new constructions and to existing buildings with a minimum of alteration. With an existing building, all that is generally necessary is to remove the old facia board and replace it with the facia of the invention.

The facia does not alter the appearance of a building for the only visible difference over a conventional facia board is that the facia of the invention is slightly thicker than the normal facia board and contains the vertical passages.

The air passing upwardly within the facia passages sweeps upwardly along the under surface of the roof deck and between the rafters which act as channels for the flow of the air. As the air flow is against the under surface of the roof deck, any air turbulence that may occur will not turn up batts of insulation located between the ceiling joists or will not disturb loose insulation.

Should any attempt be made during construction of the dwelling to force insulation outward above the upper wall plate, the insulation in this area will not block the air flow because of the fact that the air flow is immediately adjacent the under surface of the roof deck.

Other objects and advantages will appear in the course of the following description.

The drawings illustrate the best method presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a vertical section of a typical dwelling embodying the roof construction of the invention;

FIG 2 is a fragmentary, enlarged vertical section of the eave area of the roof;

FIG 3 is a plan view of the facia with parts broken away;

FIG. 4 is a perspective view of a modified form of the facia;

FIG. 5 is a perspective view of a second modified form of the facia;

FIG. 6 is a fragmentary vertical section of a third modified form of the facia;

FIG. 7 is fragmentary vertical section showing a fourth modified form of the invention;

FIG. 8 is a view taken along line 8--8 of FIG. 7;

FIG. 9 is a vertical section of dwelling utilizing a series of baffles in the spaces between adjacent rafters;

FIG. 10 is an enlarged fragmentary vertical section showing the attachment of the baffle to the inner facia member;

FIG. 11 is a perspective view of the baffle;

FIG. 12 is a view similar to FIG. 9 employing a modified form of baffle;

FIG. 13 is a perspective view of the baffle of FIG. 12; and

FIG. 14 is a perspective view of a further modified form of the baffle.

The drawings illustrate a typical dwelling including a vertical outside wall 1, which is formed of a series of spaced studs 2. A top plate 3 is secured to the upper ends of the studs and sheathing 4 and siding 5 are applied to the outer surface of the studs 2 to provide the outer wall, while a layer of plasterboard or plaster 6 is applied to the inner surface of the studs 2 to provide the interior wall surface.

A series of ceiling joists 7 are supported on the top plate 3 and a ceiling 8 is formed of plasterboard or plaster and is supported from the ceiling joists.

The roof includes a series of rafters 8 which are supported on the top plate 3 and are nailed to the ceiling joists 7. The rafters carry a roof deck 10 and conventional wood, asbestos or asphalt shingles 11 are secured to the outer surface of the roof deck.

The ridge or high point of the roof is provided with a continuous louvered vent 12 so that air located within the attic space above the ceiling 8 can flow outwardly through the vent 12.

A facia 13 is secured to the outer ends of the rafters 9 and a soffit board 14 is nailed to the lower ends of the rafters 9 as well as to a stringer 15 secured to the studs 2.

To retard the loss of heat from the interior of the dwelling, insulation 16 is located between the ceiling joists 7 and may take the form of batts of fiber glass or loose insulation such as rock wall, or the like. In some cases the insulation 16 may extend over the top-plate 3 to the area above the soffit 14.

According to the invention, the facia 13 is a dual wall member including an outer facia board 17 and an inner backing member 18 which are spaced apart by a series of vertically extending spacers 19 to provide a series of vertical passages 20. A screen 21 or other perforated member is connected between the facia board 17 and the backing member 18 to prevent insects from passing through the passages 20 to the attic space. The facia 13 can be fabricated from any desired material such as wood, wood products such as hardboard, metal, plastic, or the like.

Air passes upwardly through the passages 20 and, as the upper edge of the backing member 18 terminates short of the roof deck 10, the air being discharged from passages 20 is directed along the under surface of the roof deck 10. The air flows upwardly along the roof deck between the channels or troughs formed by the roof deck and the rafters 9 and is discharged through the vent 12 at the ridge of the roof. As the passages 20 extend along the entire length of the facia, a substantial volume of air is continuously drawn upwardly through the passages 20 and flows along the under surface of the roof. Similarly, the outlet at the roof ridge extends continuously along the ridge so that the outward air flow from the attic area is not restricted. This air flow prevents the build-up of a thermal gradient between the portion of the roof located above the dwelling and that portion of the roof deck located outwardly of the building above the soffit 14. As there is no appreciable thermal gradient along the entire area of the roof, ice dams or packs will not be formed and thus the problems which accompany the formation of ice packs will be eliminated. As a further advantage, the air flow which passes upwardly along the under surface of the roof deck 10 will serve to remove the accumulation of attic heat in warm weather and thereby provide more comfort for the dwelling in warmer weather.

FIG. 4 illustrates a modified form of the invention in which the front facia board 17 and the backing member 18 are spaced apart by a series of Z-shaped spacing members 22. The flanges of the spacing members 22 can be secured to the respective members 17 and 18 by adhesives, screws or the like. The spaces or passages 20 between the spacers 22 function as previously described to permit the upward flow of air through the facia which then is directed along the under surface of the roof deck 10 to the outlet 12 formed in the roof ridge A screen 21 or perforated member can be secured to the lower edges of the facia board 17 and backing member 18 as in the first embodiment.

FIG. 5 illustrates a second modified form of the invention in which the front facia board 17 and backing member 18 are spaced apart by a corrugated spacer 23. The spacer 23 can be secured to the members 17 and 18 by adhesives or fasteners and if the corrugations are sufficiently small the corrugated member 23 will serve the dual function of spacing the members 17 and 18 as well as preventing insects from passing upwardly within the passages 20.

FIG. 6 is a further modified form of the invention in which the facia 24 is formed of a single piece of plastic or metal and includes an inner wall 25, and an outer wall 26, which are connected together along their lower edges by a bottom wall 27. The inner and outer walls 25 and 26 are spaced apart by a series of spacers 28 which are positioned at intervals along the length of the facia 24.

The facia 24 is secured to the outer ends of the rafters 9 by a series of spikes 29 which extend through the spacers 28, and into the rafters 9. in some cases the gutter or eaves trough, not shown, may also be secured to the facia by use of the spikes 29.

To permit air to flow upwardly within the passages 30 between the inner and outer walls, 25 and 26, the bottom wall 27 is provided with a series of slit vents 21. As shown in FIG. 6, the slits are arranged so that the air moving upwardly through the vents 31 will be directed forwardly toward the outer wall 26.

As in the case of the first embodiment, the upper edge of the inner wall 25 terminates short of the roof deck 10 so that the air flowing within the passages 30 will be deflected along the underside of the roof deck and then move upwardly to the vent 12 in the roof.

To permit the outer wall 26 to be readily bent or deflected with respect to the inner wall, the corner 32 is provided with an enlarged radius so that the outer wall can be bent downwardly to a position where the spacers 28 can be inserted between the walls 25 and 26.

The lower edge of the inner wall 25 is provided with an inwardly extending shoulder 33 and, as shown in FIG. 6, the soffit board 14 is supported on the shoulder 33. In this embodiment, the soffit board is urged downwardly against the shoulder 33 by a generally circular plastic strip 34 which is wedged between the lower surface of the rafters 9 and the soffit board 14.

FIG. 7 illustrates another modified form of the invention in which the facia 35 is formed of a single piece of material and includes an inner wall 36 an outer wall 37 which are joined together along their bottom edges by a bottom wall 38. Spacers 39 are located between walls 36 and 37 and define vertical passages 40. In this embodiment, the bottom wall 38 is provided with a series of small holes or openings 41 which permit air to pass upwardly into the passages 40. The holes 41 are of such a size that they will prevent the entry of insects into the passages 40.

As in the case of the embodiment shown in FIG. 6 the lower end of the inner wall 36 is provided with a shoulder or ledge 42 which supports the soffit board 14 and the lower edge of the outer wall 37 is provided with an enlarged radius, as indicated at 43, to permit the outer wall 37 to be bent or pivoted with respect to the inner wall 36.

A clip 44 is positioned against the outer surface of each spacer 39, and the clip and spacer are nailed to the ends of the rafters by spikes 45. As shown in FIG. 7, the upper edge of the outer wall 37 is provided with a hook 45 which engages the upper ends of the clips 44 and maintains the outer wall 37 in position with respect to the spacers 39 and the inner wall 36. The structure shown in FIGS. 7 and 8 has the advantage that the nails or spikes 45 are not visible from the exterior as they are covered by the outer wall 37.

The structure shown in FIGS. 7 and 8 functions in a manner similar to that previously described. The air passes upwardly through the holes 41 and into the vertical passages 40 between the spacers 39. As the upper edge of the inner wall 36 terminates short of the roof deck 10 the air is deflected toward the under surface of the roof deck where it passes to the vent 12 at the upper end of the roof.

While the drawings illustrate a continuous outlet at the ridge it is contemplated that various types of outlets can be substituted. For example, a series of vents can be located along the length of the ridge or cupolas, roof louvers or corbelled chimneys can also be utilized as the vent at the high point of the roof.

FIGS. 9-11 illustrate another form of the invention in which a baffle is utilized to insure that the air is directed along the undersurface of the roof deck without possible interference from insulation located above the top plate and between the ceiling joists. Ceiling insulation is normally used in one of two forms; fibrous batts or loose particulate material. With the use of fibrous batts there is a tendency for the insulating workmen to jam the batts into the spaces above the top plate of the exterior wall so that the batts will engage the roof deck and prevent or reduce air flow from the facia upwardly along the under surface of the roof deck. If the spaces above the top plate are clogged with insulation, the necessary air flow to prevent the formation of ice dams cannot be achieved.

With the use of loose insulation in the ceiling, the air flow from the facia along the undersurface of the roof deck may, under certain conditions, tend to blow back the loose insulation from the portion of the ceiling adjacent the top plate of the exterior wall with the result that the cold air flowing along the roof deck is in immediate proximity to that portion of the ceiling and frozen condensation or frost can develop on the room interior side of the ceiling in sub-freezing temperatures.

To eliminate these problems, a baffle 46 is utilized to insure that air flow is unobstructed along the underside of the roof deck and FIGS. 9-11 show the baffle 46 employed with the construction of FIG. 6. The baffle 46 has a generally trough-like shape and includes a bottom 47 and a pair of side flanges 48 which extend upwardly from the bottom and serve to space the bottom beneath the roof deck 10 to provide a channel 49 for the passage of air from the upper end of the facia to a location inwardly beyond the upper plate 3.

To position the baffle between the rafters 9, the lower or forward edge of the baffle is provided a double reverse bend 50 which defines a slot 51 that receives the upper edge of the inner facia member 25. The engagement of the facia member 25 with the slot prevents displacement of the baffle in a direction parallel to the rafters 9. The inner end of the baffle 46 is normally supported on the insulation 16, and depending on the nature and the quantity of insulation, the inner end can be in close proximity to the roof deck 10 or can be spaced a considerable distance beneath the roof deck.

The air flowing upwardly within the passages 30 of the facia will pass through the various channels 49 defined by the baffles 46 and the roof deck to the outlet in the ridge of the roof. The baffle 46 insures that an air passage is provided along the undersurface of the roof deck beyond the critical area above the top plate 3. If the insulation 16 is in the form of batts, the air channels 49 will remain open even though the batts are jammed into the space above the top plate 3, while if loose insulation is employed, the baffle will prevent the loose insulation from being blown back away from the exterior wall.

The baffle 46 can be used with any type of roof construction having an air inlet in the facia or soffit, and is preferably fabricated from a lightweight, non-corrosive material, such as thin-guage aluminum or plastic, which can be cut longitudinally by the workman, if necessary, in order to fit the baffle in the space between the rafters. The length of the baffle is not critical and it can have any length which will enable the baffle to bridge the area above the top plate 3, or extend inwardly a substantial distance beyond the top plate, if necessary to assure a deck-sweeping free flow of air. In restricted attic spaces, such as flat or very low-pitched roofs, it may be desirable to have the baffles extend all the way to the ridge to assure the necessary air flow.

FIGS. 12 and 13 illustrate a modified form of a baffle as associated with the facia construction of FIG. 6. In this embodiment, the baffle 52 which can be formed of metal, plastic, or the like is provided with a series of parallel, upstanding ribs 53. The lower end of the baffle 52 is located adjacent the inner facia member 25 and the upper end extends inwardly beyond the upper plate 3. The baffle 52 is adapted to be utilized with insulation 16 in the form of fibrous batts, and the batts jammed into space above the top plate 3 act to hold the baffle up against, or in close proximity to the roof deck.

The ribs 53 serve a dual function in that they act to space the bottom surface 54 of the baffle 52 from the roof deck to provide passages for the flow of air, and secondly, the ribs provide visual guides for cutting the baffle longitudinally to fit between the rafters. Normally, the rafters are spaced 16 inches on center, thereby providing a spacing of 14 3/8 inches between rafters when using 1 5/8 inch lumber. Thus, the baffles are normally fabricated with a width of approximately 14 inches. However, where there are obstructions in the roof, such as chimneys, or dormers, or at the ends of the roof, the spacing between rafters can be less than 14 3/8 inches. In this case the baffle would be cut longitudinally to fit the space between the rafters.

As shown in FIG. 13, the outer ribs 53a and 53d are spaced apart 12 inches, while the spacing between ribs 53a and 53b is 2 inches, the spacing between ribs 53b and 53c is 6 inches and the spacing between ribs 53c and 53d is 4 inches. With this spacing between ribs, the baffle can be readily cut into any desired width by merely cutting along a rib. For example, if a baffle width of 10 inches was required in order to fit a space between rafters, the baffle would be severed along ribs 53b and 53d, while if a baffle width of 6 inches was desired the baffle would be severed along the ribs 53b and 53c. Thus, the spacing of the ribs 53, as illustrated in FIG. 13 provides a convenient method enabling the operator to readily cut the baffle to the desired width to fit the space between the rafters, or baffle segments can be compounded into baffles having widths greater than 14 inches to satisfy wider structural spacings. For example, a 20 inch spacing could be satisfied by combining a 14 inch baffle with a 6 inch segment.

FIG. 14 illustrates another form of the baffle. In this embodiment, the baffle 55 includes a bottom surface 56 and a series of upstanding ribs 57. The baffle 55 is utilized in the same manner as the baffle 52. It is contemplated that the baffle 55 can be extruded or molded from various materials including metals, such as aluminum, or plastic materials such as polyethylene, foamed polyurethane or glass fiber reinforced polyester resin.

The use of the baffles 46, 52 or 55 provides a passage for air flow in the critical area above the top plate of the exterior wall and insures that the air will be directed along the undersurface of the roof deck without interference from insulation batts and without disrupting loose insulation in the ceiling. By insuring the free flow of air along the undersurface of the roof deck, ice dams on the roof will be eliminated.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

Claims

I claim:

1. In a dwelling, a vertical wall, a series of generally parallel spaced rafters supported on the wall with the outer ends of the rafters projecting outwardly beyond said wall, a roof deck supported by the rafters with the spaces defined by adjacent rafters and said roof deck defining channels for the flow of air, a facia attached to the outer ends of the rafters, said facia comprising an outer facia member and an inner backing member and spacing members for spacing said outer facia member and said backing member apart, said spacing members being located at intervals along the length of said facia with the spaces between said spacing member comprising generally vertical passages with the lower ends of said passages communicating with the exterior and the upper ends of said passages located immediately beneath said roof deck and communicating with said channels, the upper edge of the backing member extending above the lower edges of the rafters and terminating adjacent the roof deck, and outlet means disposed at a high point of said roof deck and communicating with said channels, air being drawn upwardly through said passages and flowing upwardly within said channels to said outlet means.

2. The dwelling of claim 1, wherein said spacing means comprises a corrugated strip connecting said facia member and said backing member.

3. The dwelling of claim 1, and including a soffit member connected to the rafters and extending between said facia and said wall, said soffit being free of openings therein.

4. The dwelling of claim 1, wherein said passages extend substantially the entire length of said facia member.

5. The dwelling of claim 1, and including foraminous means disposed across the passages to prevent entry of foreign objects into the space between the rafters.

6. The dwelling of claim 1, wherein the lower ends of the inner and outer members are connected integrally by a bottom wall, and said bottom wall is provided with a series of openings.

7. The dwelling of claim 6, wherein said openings are slits arranged to direct air passing upwardly therethrough toward said outer wall.

8. The dwelling of claim 6, wherein the longitudinally extending corner joining the bottom wall and the outer member is provided with an enlarged radius serving as a hinge to permit said outer member to be pivoted with respect to the bottom wall.

9. The dwelling of claim 1, wherein the lower end portion of the inner member is provided with a ledge facing in a direction away from said outer member, and said dwelling includes a soffit member supported on said ledge.

10. The dwelling of claim 9, and including a wedge member disposed adjacent the inner wall and wedged between the upper surface of the soffit member and the lower portion of the rafters to urge said soffit member into engagement with said ledge.

11. The dwelling of claim 1, and including a ledge located on the lower end portion of the backing member and extending in a direction away from said facia, and a soffit member extending between said vertical wall and the backing member and supported on said ledge.

12. The dwelling of claim 9, and including a series of baffles with each baffle being disposed between adjacent rafters and having a width substantially equal to the spacing between the adjacent rafters, said baffles bridging the vertical wall and each baffle having a series of upstanding longitudinal ribs adapted to space the baffle from the roof deck and provide unobstructed air flow passages along the underside of the roof deck.

13. In a dwelling, a vertical exterior wall, a series of generally parallel spaced roof members supported on the wall with the outer ends of the roof members projecting outwardly beyond the wall, a roof deck supported by the roof members with the spaces defined by adjacent roof members and said roof deck defining channels for air flow, air inlet means communicating with the outer portions of the channels, said outer portions being located outwardly of said exterior wall, air outlet means communicating with the inner portions of the channels and located inwardly of said exterior wall, baffle means disposed for vertical movement within the channels and bridging the exterior wall, said baffle means being spaced above the upper extremity of said exterior wall and the outer end of said baffle means extending a substantial distance outwardly of said exterior wall and being in communication with said air inlet means, said baffle means including a surface spaced beneath the roof deck to provide a passage therebetween, and at least one spacing member extending upwardly from said surface and disposed to space the surface from the roof deck.

14. The dwelling of claim 13, and including a batt of fibrous insulation disposed in the channel beneath the baffle means, said batt engaged with the baffle means and acting to urge said baffle means upwardly toward the roof deck.

15. The dwelling of claim 13, wherein said spacing members are generally parallel ribs extending longitudinally of said surface.

16. The dwelling of claim 15, wherein the surface has a width slightly greater than 14 inches and four ribs extend upwardly from said surface, the spacing between the first pair of adjacent ribs being approximately 2 inches, the spacing between a second pair of adjacent ribs being approximately 6 inches and the spacing between a third pair of adjacent ribs being approximately 4 inches.

17. In a dwelling, a vertical exterior wall, a series of generally parallel spaced roof members supported on the wall with the outer ends of the roof members projecting outwardly beyond the wall, a roof deck supported by the roof members with the spaces defined by adjacent roof members and said roof deck defining channels for air flow, air inlet means communicating with the outer portion of the channels, said outer portions being located outwardly of said exterior wall, air outlet means communicating with the inner portion of the channels and located inwardly of said exterior wall, baffle means located within the channels and bridging the exterior wall, said baffle means including a surface spaced beneath the roof deck to provide a passage therebetween, and at least one spacing member extending upwardly from said surface and adapted to space the surface from the roof deck, said air inlet means including a facia attached to the outer ends of said roof members, said facia including an outer facia member and inner facia member spaced from the outer facia member with the space between said facia members comprising a series of generally vertical openings, the outer end of said baffle means being engaged with the inner facia member and the vertical openings in said facia being in communication with said passages.

18. The dwelling of claim 17, and including connecting means for removably connecting the outer end of said baffle means to the inner facia member.

19. The dwelling of claim 18, wherein said connecting means includes an inverted U-shaped member disposed to receive the upper edge of said inner facia member.

20. In a dwelling, a vertical exterior wall, a series of generally parallel spaced roof members supported on the wall with the outer ends of the roof members projecting outwardly beyond the wall, a roof deck supported by the roof members with the spaces defined by adjacent roof members and said roof deck defining channels for air flow, air inlet means communicating with the outer portions of the channels, said outer portions being located outwardly of said exterior wall, air outlet means communicating with the inner portion of the channels and located inwardly of said exterior wall, and a baffle member located within the channelsand bridging the exterior wall, at least a portion of said baffle member being spaced beneath the roof deck to provide a passage therebetween, said air inlet means including a facia attached to the outer ends of said roof members, said facia including an outer facia member and an inner facia member spaced from the outer facia member with the space between said facia members comprising a series of generally vertical openings, the outer end of said baffle member extending outwardly of the exterior wall and terminating adjacent said inner facia member whereby the vertical openings in said facia are in communication with said passages.