VALVED COVER FOR PERFORATED-STRIP SOFFIT VENTS
A valved cover is described for controlling air flow through perforated-strip-type soffit vents surrounding houses. The narrow, continuous vents are completely enclosed except for valved portholes in the cover, the flap valves being stiffly hinged to stay open (and quiet) in most weather to allow two-way ventilating air flow between outdoors and attic/roof space. The valved covers “harness” very strong winds: those on the the windward have their valves blown closed, blocking potentially destructive wind/rain entry into the attic/roof space, while those facing lee sides remain open so that the attic/roofspace is connected only to the wind-depressurized lee-side air and is therefore itself depressurized, helping hold the roof envelope together. The valved covers can be factory-mounted on the soffit panels and flat-folded for compact shipping and handling.
The invention controls air flow through perforated-strip soffit vents into and out of attics.
BACKGROUND OF THE INVENTIONEave soffits are now often composed of solid boards having a vent composed of a strip of small, close-spaced perforations, the boards and their perforated strip vents extending around the house perimeter. Such a perforated strip's main advantage over traditional rectangular soffit vents is clear: no separate grille and insect screen are needed since the small perforations or slits serve both functions and yet provide more than adequate open area for attic/roof space ventilation. The solid sheet soffit—typically of fiber-cement or wood fiber composite boards of soffit width and considerable length—can be installed strongly for hurricane-prone regions and so finds favor there.
As with rectangular vents, however, hurricane-force winds can push rain water up through the perforations and carry it up into the roof space, sometimes ruinously. Further, such winds can pressurize the roof space through the vents in some fairly common house layouts, increasing the net pressure trying to push off roof sheathing, gables and the soffits themselves into the wind-induced depressurized areas outboard of the roof space envelope. Today's soffit vents increase the odds of the house being badly damaged in such ways.
Valving the soffit vents can help save the house: the valves can block rain entry while substantially reducing the net pressure trying to push the roof envelope apart. Valved vents are designed to rest open in normal conditions to allow two-way ventilation, but be pushed closed on the windward whenever an inward wind pressure differential reaches a certain strength, thereby blocking entry of wind and windborne rain. Since the lee-side vents continue to lie open, the roof space air connects only with the depressurized air there and so avoids pressurization and in fact (given that other roof vents are closed off or themselves valved) the roof space air is itself strongly depressurized in strong winds.
(The valved vent action can also help hold the whole roof structure down on the house, but only where the roof framing is of a once-typical type of rafter construction.)
In U.S. Pat. No. 6,484,459 B1, Platts discloses this concept of wind-actuated valved-vent depressurization of attic/roof space, and in “Quiet Acting Valved Vent” (Pat. Pend. Mar. 11, 2015) he and Russell describe a pleated design for rectangular soffit vent openings, offering almost completely unrestricted open area in normal and even most gusty conditions. That device, however, and indeed any prior-art valve device (as reviewed in Platts, Russell Mar. 11, 2015) is not readily or economically adaptable for covering perforated strip vents.
SUMMARY OF THE INVENTIONA basic object of the present invention, a valved cover for perforated-strip soffit vents, is to close and block wind-blown rain entry into the roof space when winds press excessively inwardly.
Another object is to help protect the integrity of a roof envelope by preventing significant pressurization of the roof space, regardless of wind direction and/or the presence of non-valved vents or air leakages into such space, by blocking wind entry through the soffit vents on the windward side or sides while allowing roof space air to exit freely through leeside valved vents.
A further object is to be usable in more strongly protecting the integrity of the roof envelope by depressurizing the roof space, generally requiring that significant air leakages be sealed and non-valved vents be blocked or valved (or otherwise designed to promote air exhaust) while roof space air exits freely through lee-side valved vents to the wind-depressurized air there.
A further object is to stay quiet even in commonly gusty wind conditions.
A still further object is to remain relatively simple and inexpensive overall, despite the bulkiness of the installed valved covers and their great length around a house, by allowing factory manufacture and assembly on soffit boards and yet be compactly shippable.
And of course a basic object is to provide unrestricted ventilation to a roof space in most weather conditions by remaining completely open to in-out air flow between outdoors and the roof space.
Terms: For greater certainty some terms are defined as follows: “House” here refers to a low-rise house or similar small building having a roof enclosing a space (“roof space”) thereunder. “Roof space” refers typically to the house attic along with the connected “soffit space” contained between roof overhang, soffit and the exterior wall portion above the soffit, more fully defined as the air space (no matter how shallow) enclosed by roof sheathing above, ceiling, soffit and wall portion below, and gables or such where present. “Roof space envelope” refers to just such enclosure. “Solid soffit” refers to a soffit constructed continuously around a house with long, solid panels (“soffit boards”) running parallel to the house wall, one long side being fixed to the wall and the other to the roof overhang's fascia structure. “Perforated strip vent” refers to a lengthwise vent strip of narrow width (typically a minor fraction of the soffit's width, and covering all or almost all of its length) running parallel to a house wall and composed of a multitude of closely spaced tiny openings together comprising sufficient open area for ventilating the roof space, the openings typically being round holes—but sometimes slits—so small that insects such as bees or spiders cannot get through. “Side” refers to a long side of such a strip vent; “end”, the short side across its end. (“Side edge” refers to an edge of a long side of a flat member.) “Porthole” refers to an opening of generally rectangular or round shape. “Flap valve” is that common type of valve where a thin flat plate has one side edge hinge-connected to, or near to, one side of an opening, the plate here resting away from the opening ready to be swung shut over it. “Fabric” means a cloth, limp and foldable. “Lee-side” or just “lee” refers to the area outboard of those sides of a house opposite to, or simply “around the corner” downwind from, the windward side(s). “Cover” refers to the main shell of the apparatus as now described; “valved cover” designates the whole apparatus.
Briefly described, the invention comprises a valved cover affixed over a perforated strip vent in a soffit board bounding a roof space to control air flow through said vent, comprising: a cover of vaulted cross-section enclosing an air space over the perforated strip vent, the cover having its side edges affixed to the soffit's solid surface along the sides of the perforated strip vent, with the cover's ends closed by end walls affixed to the cover and the soffit's solid surface to complete the cover's enclosure of the air space; at least one side slope or sidewall along the length of the cover having portholes offering a total open area similar to the enclosed perforated strip vent's open area; flap valves hinge-attached to the cover with a certain hinging stiffness and shaped and positioned sufficiently inboard of the portholes so that in most weather conditions the flap valves leave clear pathway for air flow inwardly or outwardly through the perforated strip vent and through the air space over the perforated strip vent and thence through the portholes to ventilate the roof space, but when subjected to outdoor wind pressures pushing inwardly toward the roof space with a certain strength the flap valves of the windward valved covers are pushed snugly closed across the portholes, blocking wind and rain entry. At the same time, those valved covers on the soffit vents around the wind-depressurized lee-sides of the house remain open, so that the roof space is connected only to the lee-side air and is itself depressurized, reducing net outward-acting air pressures trying to force apart the roof space envelope.
In one embodiment of the present invention the valved cover is comprised of: a first sidewall having its bottom edge hinge-connected to the soffit along a first side of the perforated strip vent; a top piece extending across much of the width of the perforated strip vent and having a first side edge hinge-connected to the top edge of the first sidewall; a second sidewall having its top edge hinge-connected to the second edge of the top piece and having its bottom edge hinge-connected to the soffit along the second side of the perforated strip vent, so completing a cover over the length and width of the perforated strip vent; portholes in the second sidewall offering a total open area greater than the enclosed perforated strip vent's open area, so that bursts of outgoing air cannot cause significant downward pressure on the valved cover; flap valves hinge-attached to the top piece and shaped and positioned sufficiently inboard of the portholes so that in most weather conditions the flap valves leave clear pathway for air flow inwardly or outwardly through the perforated strip vent; end walls made separately and ready to be inserted into and affixed to the cover and the soffit's solid surface to complete the cover's enclosure of the air space; wherewith the cover can lie flat-folded atop the soffit board to allow factory assembly thereon and yet allow compact packaging and shipping, then raised into final vaulted form and formed as the complete valved cover by inserting and securing the endwalls.
In a preferred embodiment of the present invention the valved cover is comprised of: a fabric top piece having a first side edge attached to the soffit along a first side of the perforated strip vent and its fabric extending across much of the width of the perforated strip vent and being there attached to a topside edge of a sidewall, the sidewall having its bottom side edge hinge-connected to the soffit along the second side of the perforated strip vent and so completing a cover over the length and width of the perforated strip vent; and the portholes in the sidewall offering a total open area greater than the enclosed perforated strip vent's open area, thereby minimizing the net pressure that roof space air can exert downward on the cover when lee-side depressurizations are strong; flap valves hinge-attached to the topside edge of the sidewall piece and shaped and positioned sufficiently inboard of the portholes so that in most weather conditions the flap valves stay open for air flow inwardly or outwardly through the perforated strip vent; a support plate positioned lengthwise under the cover and having one long side edge hinge-connected to the cover's underside and its opposite long side edge unattached on the perforated vent strip, the support plate being generously apertured; stops such as short pegs affixed along the perforated strip vent and protruding slightly up from the surface of same; end walls of fabric attached to or continuous with the fabric top and the soffit's solid surface; wherewith the whole valved cover can first lie flat-folded atop the soffit board to allow factory assembly thereon and yet allow compact packaging and shipping, and then be raised into final vaulted form and strongly supported there by the support plate, which has itself been rotated up by its hinged-connected long side edge, dragging its opposite long side edge forward over and just past the stops which then restrain the opposite long side edge from slipping backward, locking the plate into a nearly upright stance with its hinge-attached long side edge up and its other long side edge down.
These and other features and aspects of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts.
Materials: While much or most of the valved cover could be made of thin metal, high-polymers will probably be best: polyvinyl chloride for the most part, offering suitably fire-safe performance; polypropylene for self-hinging valve parts, comprising very little fire load; polyester fabric where needed, again offering fire-safe performance. There's essentially no UV exposure, and little fatiguing flexing even of the valve hinges since they're designed to close only in uncommonly stormy conditions, as noted below.
That openness is further illustrated in
In
On the lee-side, however, sudden depressurizations“pulling” a first rush of air out of the roof space can briefly press strongly downward on 1, potentially presenting a structural problem; but that pressure is minimized, according to the invention, by making the open area of the portholes 6 significantly larger than that of the vent 8, so keeping the air pressure within the cover-enclosed space almost equal to that in the soffit space/roof space, SS and RS, in such instances. (That porthole area is easy to achieve: perforated strip vents typically offer just 5 sq. in. of opening per foot of length.) Further, such an outgoing rush of air from the roof space is very short-lived, in that little air can flow out when little replacement air can flow in.
As suggested by the arrow below the soffit, the valved cover's closure stalls upward air flow significantly below the soffit. In hurricane-force winds the rain's upward momentum from below that stalled region can carry some up against the underside of the soffit 9, but there's no pressure differential/air flow to carry the splatter through the perforations 8.
Also apparent in
The valved vents as shown above are “nestably” shaped, which would allow economically compact shipping to distributors and final construction sites separately from the soffit boards. That, however, would leave some demanding work for the job site: attaching the valved vents to the soffit boards. Costs would be increased and quality assurance could be undermined even if done in ideal weather. Complete factory manufacture is strongly desirable.
Unpackaged at the job site, the flat-folded valved covers must first be raised into their operative form before installing the soffits. In the embodiment as shown in
The flap valve 7 in
Installing continuous soffits around any house will always require cut-and-fit at some corners and other stops. On-site cutting across a standard board and its valved cover could be done, with the enclosure of the cut-off valved cover then “made good” with an extra end wall plugged in—but not easily. A much simpler procedure is shown in
Building codes for storm-prone regions may generally (and arbitrarily of course, wastefully) specify that solid soffit boards span no more than 2 ft; if eaves are wider than that, cross framing must be laboriously installed between the house wall and fascia at 2 ft. intervals to support the soffit boards. Such frames complicate the use of valved vent covers.
While this invention has been described with respect to just a few similar embodiments thereof, it will be appreciated by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit of the claimed invention.
Claims
1. A valved cover affixed over a perforated strip soffit vent to control air flow through said vent, comprising:
- a cover enclosing an air space over the perforated strip vent, the cover having its side edges affixed to the soffit's upper surface along the long sides of the perforated strip vent;
- an end wall closing each end of the cover, each end wall being affixed to the cover and the soffit's upper surface to complete the cover's enclosure of air space over the perforated strip vent;
- portholes in at least one side slope of the cover, the portholes offering a total open area similar to the perforated strip vent's open area and so allowing ventilating air flow inward and outward between outdoors and a roof space;
- flap valves positioned inboard of the portholes and hinge attached to the cover, the hinging having a certain stiffness holding the flap valves away from the portholes;
- whereby in most weather conditions the flap valves remain quiet and leave clear pathway for air flow inwardly or outwardly through the perforated strip vent and through the air space over the perforated strip vent and thence through the portholes to ventilate the roof space, but when subjected to outdoor wind pressures pushing inwardly toward the roof space with a certain strength the flap valves are pushed closed across the portholes, thereby blocking wind and rain entry into the roof space; while at the same time those soffit vents located around the wind-depressurized lee-sides of the house, similarly covered with the valved vent covers, remain open so that the roof space is connected only to the lee-side air so the roof space is itself depressurized, reducing net outward-acting air pressures trying to force apart the roof space envelope.
2. A valved cover according to claim 1 comprising:
- a first sidewall having its bottom edge hinge-connected to the soffit along a first side of the perforated strip vent;
- a top piece extending across much of the width of the perforated strip vent and having a first side edge hinge-connected to the top edge of the first sidewall;
- a second sidewall having its top edge hinge-connected to the second edge of the top piece and having its bottom edge hinge-connected to the soffit along the second side of the perforated strip vent;
- portholes in the second sidewall offering a total open area greater than the perforated strip vent's open area, thereby minimizing the net pressure differential that roof space air can exert downward on the valved cover when leeside depressurizations are strong;
- flap valves hinge-attached to the top piece with the hinging having a certain stiffness;
- end walls insertable into each end of the valved cover;
- wherewith the valved cover less its end walls can be folded flat atop the soffit board for compact packaging and shipping to the job site, where before installation on the house the valved cover is raised into its vaulted form enclosing an air space above the perforated strip vent and the end walls are inserted and affixed to support the valved cover's vaulted form and complete its enclosure of the air space.
3. A valved cover according to claim 2, wherein:
- the end walls are made of fabric permanently attached to the ends of the valved cover and the soffit thereunder;
- a support plate is positioned lengthwise under the valved cover, the plate having one side edge hinge-connected to the cover's underside, the plate's opposite side edge resting unattached atop the perforated vent strip, the plate's width being the desired final height of the valved cover and the plate being generously apertured to allow air to flow freely through it;
- stops such as short pegs are affixed along the perforated strip vent under the support plate;
- wherewith the complete valved cover can be folded flat atop the soffit board for compact packaging and shipping to the job site, where before installation on the house the valved cover is raised into its vaulted form enclosing an air space above the perforated strip vent, thereby pulling up the hinge-connected side edge of the support plate and dragging forward the support plate's opposite side edge partly across the perforated strip vent and over and just past the stops, the stops then keeping the plate's opposite side edge from slipping backward and so locking the plate into a suitably upright stance to support the valved cover's vaulted form.
4. A valved cover according to claim 2 wherein a single fabric piece replaces the first sidewall and the top piece, the fabric piece having a first side edge attached to the soffit along a first side of the perforated strip vent, the fabric piece thence extending across much of the width of the perforated strip vent and being there attached to the topside edge of the opposite sidewall, and the ends of the fabric piece forming the fabric end walls to complete the valved cover attached to the soffit panel to enclose the perforated strip vent, wherewith the complete valved cover can be folded flat atop the soffit board for compact packaging and shipping to the job site, where the valved cover is raised into its vaulted form enclosing an air space above the perforated strip vent, thereby pulling up the hinge-connected side edge of the support plate and dragging forward the support plate's opposite side edge partly across the perforated strip vent and over and just past the stops, the stops then keeping the plate's opposite side edge from slipping backward and so locking the plate into a suitably upright stance to support the valved cover's vaulted form.
5. A method for improving a house's resistance to damage from hurricane-force winds and rains by controlling air flow through perforated-strip vents of soffit boards enclosing the eaves around the house, comprising steps of:
- providing valved covers for the perforated strip vents, the valved covers having a plurality of portholes therethrough, with a plurality of flap valves operably attached to an inner surface of the cover inboard of and spaced away from the portholes, said flap valves being stiffly hinged to remain open and quiet except when subjected to very strong inward-acting wind pressures which close the flap valves over the portholes to block wind and rain entry therethrough;
- affixing the valved covers atop the soff it boards over their perforated strip vents to enclose an airspace bounded by the valved cover and said vent;
- folding the valved covers flat atop the soffit boards, thereby allowing compact packaging and shipping to the house;
- thence unfolding the valved covers and supporting them in their vaulted form over the perforated strip vents; and
- installing the soffit boards integral with the valved covers to enclose the eaves around the house;
- whereby the flap valves of the valved covers leave the portholes open in most weather conditions to allow two-way air flow between outdoors and roof space through the perforated strip vents to provide roof space ventilation, but those windward flap valves facing a certain amount of inflow pressure from windstorms are pushed closed over their portholes, that closure blocking wind/rain entry through the soffits' perforated strip vents; while at the same time the valved covers on the lee-side remain open so that the roof space air connects only with the wind-depressurized lee-side air and is therefore itself depressurized, substantially reducing net outward forces induced by wind action on the roof envelope and so helping keep the envelope intact.
6. A valved cover according claim 1 formed flexibly to allow flat-folded installation on the perforated strip soffit vent for compact packaging and shipping to a job site, and equipped to be raised and affixed into a vaulted form enclosing an air space above the perforated strip vent.
Type: Application
Filed: Feb 8, 2016
Publication Date: Aug 10, 2017
Inventor: Robert E. Platts (Ottawa)
Application Number: 15/018,562