Frequently Asked Questions about The Edge™ Vent, Air Vent’s NEW Shingle-Over, Roof-top Installed Intake Vent
Q: Is there a potential for pooling water behind The Edge Vent on 3/12 & 4/12 pitch roofs?
A: No, The Edge Vent was designed to shed water at these roof pitches. Any water will be traveling from the peak of the roof all the way down to the edge of the roof with increased speed and volume. Thus, the water should safely clear The Edge Vent and the roof. The Edge Vent was designed so that when installed on a minimum pitch 3/12 roof the roof would still maintain an angle of decent towards the bottom edge of the roof. When installed on a 3/12 pitch, it can be deceiving because the angle is not very steep; only 2-3 degrees and may look like a pool area. It rapidly transitions back to 14 degrees.
Q: How will The Edge Vent perform in snow, ice regions of the country?
A: In terms of structural integrity, The Edge Vent will perform similarly to Air Vent’s ShingleVent® II ridge vent, which is the same exact copolymer resin material as The Edge Vent. ShingleVent II has been on the market 20+ years on hundreds of thousands of roofs in northern climates.
As for its durability in northern climates, The Edge Vent should last the life of the roof provided that it is not subjected to conditions beyond what starter course and first course shingles typically experience.
Finally, regarding weather protection, interior features have been incorporated into the design of The Edge Vent to help prevent problems associated with northern climates (ice damming, snow accumulation, snow & moisture infiltration, etc.). Those interior features are: an internal weather filter (the same filter, by the way, used in ShingleVent II); patented internal baffles; and a patented drainage system.
Q: Will every brand of shingle correctly align on The Edge Vent in terms of nailing requirements?
A: No, every brand of shingle will not correctly align on The Edge Vent in terms of nailing requirements. Even if they did, Air Vent would not make that claim because we do not control shingle manufacturer’s nailing requirements for current shingles or for roofing materials that will be introduced to the market in the future. It is very possible that the installer of The Edge Vent will have to deviate from the shingle manufacturer’s recommended nailing location to ensure that both The Edge Vent and the shingles are adequately secured to the roof deck. Note: Nailing over the slot opening should be avoided to prevent damage and possible shingle and product wind uplift. Avoid nailing between 5-3/4” and 7-1/4” from the drip edge of The Edge Vent.
For example, for shingles that have a 5 5/8” course exposure, it should be acceptable to nail the first course right above the course exposure given that there will be at least a ½” overhang. A ¾” overhang will provide even more distance from the slot. NOTE: The slot is cut 5” from the edge flashing beneath the vent. The actual drip edge of the vent extends another inch beyond the edge flashing located beneath the vent for a total distance of approximately 6” from the slot. With a ½” shingle overhang, the lower edge of the shingle should be 6 ½” from the slot. This leaves approximately 1” between the shingle overlap line with a 5 5/8” course exposure and the lower edge of the slot.
Q: What does Air Vent recommend regarding the usage and placement of underlayment with The Edge?
A: With regard to the placement of underlayment, Air Vent recommends it be placed both under The Edge Vent (i.e. directly on the deck) and over The Edge Vent. NOTE: The slot should also be cut into the underlayment that is applied directly over the roof deck slot before securing The Edge Vent to the roof.
Use the type of underlayment commonly used for the specific climate and ensure that local building code requirements are met. For example, in snow regions, the underlayment typically used at the edge of the roof (e.g. ice and water shield) should be installed over the top of The Edge Vent to ensure proper protection from any water that could potentially backup under the shingles on the roof top. Additionally, Air Vent recommends that the same underlayment also be used to protect the roof deck directly beneath the vent in northern climates. In warmer regions of the country, with little or no snow, the use of standard shingle underlayment beneath and over The Edge Vent should be sufficient.
Q: In northern climates where snow is common, can I use window flashing tape or caulk under The Edge Vent instead of applying ice and water shield under The Edge Vent the first 5 inches on the deck?
A: Air Vent will not specify what materials are to be used beneath The Edge Vent in any climate. However, it is recommended that waterproofing underlayment or a similar performing product be used beneath The Edge Vent to protect the roof deck from possible moisture damage in northern climates. NOTE: Local building code should be referenced before an alternate material is selected.
Q: Is the integrated, built-in end plug truly sealed from the weather?
A: The integrated end plugs of The Edge Vent terminate each end of the vent to help prevent weather infiltration. The end plug feature is essentially a vertical rib with a top edge that matches the contour of the vent’s curved, tapered profile. The top half of The Edge Vent rests on this rib in the assembly and provides a tight joint once the installation is complete. Additional weather protection for this joint is provided by the shingles which typically extend ½” to ¾” beyond the end plug of The Edge Vent at the gable end of a roof. It should be noted that the slot is to be terminated at least 6” inside of the gable end wall and The Edge Vent should be installed flush with the edge of the roof. For maximum roof deck protection, at the edge of the gable end, it is recommended that the roof deck be covered with underlayment beneath the vent.
Q: Will Air Vent specify a type of fastener?
A: Air Vent will not specify a particular fastener to be used for the installation of The Edge Vent or for shingles installed over the product because of possible variations in the construction details. Air Vent does specify that the roofing nail used to secure The Edge Vent to the roof deck AND to install the shingles over the vent be of sufficient length to fully penetrate the underside of the roof deck. However, Air Vent recommends that the fastener must be at least 1-3/4” long.
Q: If the ridge vent (exhaust vent) is snow covered and The Edge Vent (intake vent) is snow covered what happens to the attic ventilation?
A: If they are both covered, then there will be no attic ventilation. Eventually, the snow will clear from both the peak and the eave and the attic ventilation system will be functioning once again. Keep in mind, the only reason The Edge Vent would be temporarily blocked is because of snow accumulation in the gutter installed below the product.
In the event that The Edge Vent is covered with snow when the ridge vent is clear, the ridge vent will evacuate heat and moisture via thermal buoyancy. Once The Edge Vent is no longer blocked, the balanced attic ventilation system will be working as normal.
Q: Will building inspectors red flag a slot opening in the roof area where nonstop waterproofing underlayment should be placed?
A: It may be possible that a roofing inspector would red flag a slot opening in the roof deck in an area required to have a waterproofing underlayment from the edge of the roof up to at least 24” inside the exterior wall line (Ref. Section 905.2.7.1 of 2006 IRC). Currently, however, there is no code which addresses a continuous roof penetration in this area of the roof. Air Vent will be working with code and regulatory agencies to address the questions as they arise.
Q: Will Air Vent specify gutter size?
A: Air Vent has never specified the gutter size for use with its product and will not do so with The Edge Vent because of the infinite variables that are structure specific. Obviously, the drip edge of the shingles can be as much as 1-1/4” further from the fascia board compared to shingle installations without The Edge Vent. Therefore, narrow profiled gutters that have long runs and significant elevation drops could present some issues. Compatibility of The Edge Vent with existing or new gutter systems will need to be investigated for each specific structure by the installer.
Q: Is there room for installer error in cutting the slot 5 inches from the roof edge?
A: Yes, as with most building construction practices, there is some latitude with the precise slot dimensions to be cut. It is recommended that the lower cut for the slot be maintained as close as possible to 5” from the drip edge flashing and that the slot width be maintained between ¾” to 1” wide (Note: An edge flashing must be used when installing The Edge Vent). A nice, straight lower cut will assist in properly locating The Edge Vent on the roof with the locating tabs on the underside the product.
Q: How do you handle Edge Vent installation with open valleys?
A: There are three possible options in dealing with open valley installations of The Edge Vent.
Option 1: Position The Edge Vent so that it terminates 2 feet from the open valley with the built-in end plug on the vent facing the open valley. Remember, the slot cut in the deck for The Edge Vent terminates 6 inches from the very end of the vent, or 2-½ feet from the centerline of the valley. Install shingle underlayment over The Edge Vent, followed by flashing material wrapped over the end of the vent onto the deck at the location facing the open valley, and then install the shingles. (NOTE: Install the valley underlayment and valley flashing as normal.) As the shingles are installed toward the valley, they will need to be cut at the end of the vent run so that the flashing covering the end plug is exposed and the shingles are completely supported by both the vent and the roof deck beside the vent. This will result in a slight step of the shingles at the end of the vent run.
Option 2: Similar to Option 1 except that the flashing is not required. After the slot is cut 2-½ feet from the centerline of the valley and The Edge Vent is installed, install a shim (field constructed) to taper the end profile of the vent to the roof deck (towards the valley and uphill from the drip edge of the roof). Install the underlayment over the vent and the shim. (NOTE: Install the valley underlayment and valley flashing as normal.) Finally, install the shingles towards the cut valley as normal. This second option could provide better aesthetics than the first option by eliminating the slight step in the shingles at the end of the vent run.
Option 3: Terminate the roof deck slot for The Edge Vent 12” from the centerline of the valley. Miter cut two sticks of The Edge Vent and install into the centerline from both sides of the valley. Depending on the gauge and features of the valley flashing metal, it may be necessary to install a shim in the valley uphill from The Edge Vent to fully support the valley flashing. Install the valley underlayment, valley flashing, and shingles as normal for an open valley roofing application. This option could be the most aesthetically pleasing of the three options.
Q: What are the roof pitch requirements for installing The Edge Vent?
A: The Edge Vent can be installed on roofs with a minimum 3/12 roof pitch. There is no maximum roof pitch.
Q: Can The Edge Vent be installed on roofs with vented nail base?
A: When using The Edge Vent with vented nail base products, there are a few things to consider:
Is there an attic space below the vented nail base which is desired to be vented? If so, is there independent intake ventilation for the attic or would The Edge be relied on to supply ventilation to both the attic and the vented nail base? If The Edge Vent is to supply intake to both, then the slot would have to be cut through the vented nail base and any other layers that may exist below in order to accomplish intake ventilation for the attic. If there is a compact (cathedral ceiling) roof application, see number 2 below.
If it is cathedral ceiling construction with vented nail base over a compact roof system, then it may be possible to cut the slot into the top surface of the vented nail base. WARNING: The manufacturer of the specific vented nail base needs to be consulted regarding the structural integrity of a continuous slot being cut in the top surface of their product. They may require that the slot not be continuous, but interrupted, to maintain the structure integrity.
Use a vented nail base that has a minimum of 1 ½” air space to allow the incoming intake air from The Edge Vent to safely travel to the exhaust vent. There are brands of vented nail base with less than 1 ½” air space but Air Vent recommends a minimum of 1 ½”.
Q: Can The Edge Vent be used with other types of intake vents on the same roof?
A: Yes, it is OK to use The Edge Vent in conjunction with all existing intake vents on the same side of the house (whatever type of intake vents they happen to be) because they will all be in the same pressure zone. Additionally, if it happens to be that there is excess intake ventilation than the exhaust system needs the intake vents become exhaust vents on the leeward side of the house.
Q: Can The Edge Vent be used on one side of the house (the side that does not have an overhang, for example) and another type of intake vent on the opposite side of the house (the side that does have an overhang)?
A: Yes, it’s OK to use The Edge Vent on one side of the house and use a different type of intake vent on the other side of the house. This will not cause any problems for the overall attic ventilation system.
Q: Could The Edge Vent be used under concrete tile? The load is 10 pounds per square foot.
A: Air Vent has not looked at this application in detail, but it could possibly work. Underlayment will have to cover the product regardless of the roof covering material. It should be able to handle the static load of 10#/sq. ft. with no problem. The concerns include attachment of the product to the roof deck and elevating the first course of tile to match the rest of the roof. We rely not only on the 10 pre-fastening locations of The Edge Vent to secure the product to the roof deck, but also the nails for the starter course and first course shingles. With a tile installation, these additional fasteners are not installed to help secure the product to the roof.
The bottom line: It could work, but Air Vent can’t say that it will at this time until more of an investigation is conducted.
Q: Are there any special considerations when trying to install The Edge Vent on a slate roof?
A: Air Vent has not performed an installation with slate roofing. It is possible that it could work, but Air Vent has not investigated all of the possible installation details that would need to be addressed. It will be critical that the underlayment is installed adequately over the vent and that the vent is secured to the roof deck at more locations than the 10 reinforced nail bosses.
Q: Could The Edge Vent be safely used for intake at the transition where a pitched roof meets a flat roof?
A: Air Vent does not recommend the use of The Edge Vent for this application where a sloped roof meets a flat roof. Not only is there an increased possibility for infiltration, the vent would be covered most of the winter with snow.
Q: Are there any concerns using Pro Flow™ Vented Drip Edge and The Edge Vent on same roof?
A: There are a couple concerns:
The top flange of the Pro Flow Vented Drip Edge is approximately 6.5”. The slot for The Edge Vent is supposed to be cut between 5” and 5-3/4” from the edge of the flashing. This means that the upper flange of the vented drip edge would have to be cut.
The space beneath the roof deck would need to be sufficient for the 18 square inches per linear foot of the combined intake Net Free Area.
Other than these two items, both intake vents should be under similar pressure conditions allowing them to perform as designed.
Q: Has Air Vent done any research on how The Edge Vent works with gutter protection products (Leaf Proof, for example)?
A: Air Vent has not tested the compatibility of gutter protection products in general with The Edge Vent.
In a quick review of the Leaf Proof gutter protection product, Air Vent does not believe that The Edge Vent will work without significant customization of the installation. This gutter protection product has features that slow the water speed down so that it will be diverted in the gutter. This requires that the first course shingles overlap the top flange of the Leaf Proof product. It may be possible to block out a sub fascia to support the gutter and create a ventilation space to allow air to get to The Edge Vent from directly below the slots. Then the gutter protection product could be flashed under the first course of shingles that are installed over The Edge Vent. Fastening of this upper flange could be challenging.
Q: How do I install The Edge Vent on a house with a 6” overhang that is insulated to the roof sheeting from inside the attic in an older home?
A: Install insulation baffles in every rafter bay to create an air space between the insulation and the underside of the roof deck. For situations where there may be limited or no access to the attic areas from the living space, it is possible to cut an access panel into the roof sheathing during the re-roof job so that the insulation baffles can be installed. The created air space will allow air to exhaust from The Edge Vent, through the roof deck slot, and into the attic area.
Q: Is it OK to install The Edge Vent 2-3 feet down from the ridge as an exhaust vent?
A: No, it’s not recommended that The Edge Vent be used up the roof as an attic ventilation exhaust vent. The product was specifically designed for intake venting applications.
Q: Can The Edge Vent be used on a gambrel roof?
A: The use of The Edge Vent at the roof transition for a gambrel roof should be acceptable. NOTE: The deck below The Edge Vent at the roof transition line will have to be protected. The contractor may want to install water proof shingle underlayment and flashing beneath The Edge Vent to finish the roof transition.
Q: Has The Edge Vent been tested in an asphalt shingle installation for fire resistance Class A applications?
A: The Edge Vent is not Class A. Perhaps one day Air Vent will have it tested/rated as such.
Q: Can The Edge Vent be installed up the roof instead of at the very edge of the roof for roofs with exposed rafter tails, for example?
A: Yes, it is acceptable to install The Edge Vent up the roof a few feet from the roof's edge to provide intake ventilation for an attic that begins further up the roof, as in an exposed rafter tail design, for example.
This document was last modified on January 12, 2008.
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