Skip to main content

Roof Edge Protection

    Scope
    Scope

    Design and construct or retrofit roof assemblies to resist wind pressures at roof edges during high-wind events.

    • Install a fully adhered roof membrane over the entire surface area of the roof deck.
    • Install code-compliant metal drip edges at eaves and gables/rakes. 
    • Secure cladding at roof edges.
      • Install asphalt shingles at eaves over an asphalt shingle starter strip that is adhered to the fully adhered membrane underlayment or the drip edge or both. Set asphalt shingles that are installed at eaves and at gables and rakes in a minimum 8-inch wide strip of flashing cement.
      • Install metal roof cladding over a “slip sheet” installed between the metal roof and the fully adhered membrane. Also, use a continuous cleat to mechanically attach the metal roofing.

    See the Compliance Tab for related codes and standards, requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home programENERGY STAR Single-Family New Homes, and Indoor airPLUS.

    Description
    Description

    The greatest stress roof assemblies experience in high wind zones is at roof edges. That is where roofs experience the highest positive and negative air pressures. Roof assemblies need to be able to resist the wind pressures that can act on them during high wind events such as hurricanes. In addition to the highest wind pressure differences, roof edges can also experience the greatest rainwater loads. In sloping roofs, all of the rainwater incident on the roof area drains downward to the roof edge.

    This guide provides guidance for the construction of roof edges in sloping roof assemblies for residential construction. The guidance is applicable to both new construction and the re-roofing of existing roof assemblies.

    During high-wind events, high localized areas of negative pressure (“suction”) occur above roof edges due to the development of vortices (Figure 1). These pressures become more pronounced with sloping roofs typical of residential construction (Figure 2 and Figure 3). Most roof covering “blow-off” occurs at roof edges for these reasons.

    During high wind events, vortices form along the edges of the roof creating areas of localized negative pressure ('suction') above the roof.
    Figure 1. During high-wind events, vortices form along the edges of the roof creating areas of localized negative pressure ('suction') above the roof. (Source: Building Science Corporation.)

     

    During high wind events, sloped roofs and flat roofs experience higher uplift forces than flat roofs with parapets.
    Figure 2. During high wind events, sloped roofs and flat roofs experience higher uplift forces than flat roofs with parapets. (Source: Building Science Corporation.)

     

    Strong wind passing over a sloped roof cause positive pressure on windward side and negative pressure on leeward side and at vortices above windward eave.
    Figure 3. As wind passes over a steep sloped roof, it generally pushes on the near side and pulls on the far side of the roof but separation of flow at the eaves can cause areas of high negative pressure, or suction, at the near side above the eave. (Source: Building Science Corporation.)

     

    In high-wind zones it is recommended – as a minimum requirement - that a fully adhered roof membrane underlayment be installed at roof eaves and roof rakes. This could be a single-ply membrane such as TPO, EPDM, or PVC, or a built-up modified bitumen, or fluid-applied membrane. Improved performance and reduced risk occurs if a fully adhered roof membrane underlayment is installed over the entire surface area of the roof deck – not just at roof eaves and roof rakes. 

    If a fully adhered roof membrane is not installed over the entire surface area of the roof deck, and a mechanically fastened underlayment is installed instead, alternative roof deck air sealing and water control requirements are necessary to provide acceptable performance and acceptable risk in high wind zones. Alternative roof deck air sealing and water control requirements can be found in the Insurance Institute for Building and Home Safety (IBHS) Fortified Home Hurricane Technical Summary.

    In high-wind zones, it is recommended that drip edges be installed at roof eaves and roof rakes (Figure 4). The following drip edge installation requirements are recommended:

    • Code compliant metal drip edges should be installed at eaves and gables or rakes (applicable codes set the minimum gauge required).
    • Drip edges should overlap a minimum of 3 inches at joints.
    • Eave drip edges should extend a minimum of ½ inch below sheathing and overlap the top of the roof sheathing edge a minimum of 2 inches.
    • The drip edge should be mechanically fastened to the roof deck at a maximum spacing of 4 inches and the fasteners should be compatible with the flashing.
    • Drip edges at eaves can be installed over the fully adhered membrane underlayment if flashing cement is used to seal the edges.
    • Drip edges at gables or rakes should be installed over the fully adhered membrane underlayment.
    Right – Install metal drip edge at roof edges in high wind and rain areas.
    Figure 4. In high-wind zones, metal drip edge should be installed at roof eaves and roof rakes. (Source: Building Science Corporation.)

     

    Asphalt shingles that are installed at eaves and gables or rakes should be installed over an asphalt shingle starter strip that is set in a minimum 8-inch-wide strip of flashing cement adhered to the fully adhered membrane underlayment and/or to the drip edge (Figure 5). Asphalt shingle courses are then installed over the starter course (Figure 6).

    Where drip edge flashing is installed over the fully adhered membrane at the eaves, flashing cement should be used to seal the upper drip edge of the flashing (Figure 7).

    With metal roof assemblies, the approach is modified to include a “slip sheet” (typically a loose laid building paper) between the metal roof and the fully adhered membrane. The function of the “slip sheet” is to account for the significant movement that metal roof assemblies experience due to temperature changes over the course of a day, week, or season. Additionally, a continuous cleat is necessary to mechanically attach the metal roofing (Figure 8).

    Right – Start asphalt shingle installation with a starter strip set in an 8-inch strip of flashing cement.
    Figure 5. Start asphalt shingle installation with a starter strip set in an 8-inch strip of flashing cement. (Source: Building Science Corporation.)

     

    Right – Install asphalt shingles over a starter strip set in an 8-inch strip of flashing cement.
    Figure 6. Install asphalt shingle courses over the starter course which is set in flashing cement. (Source: Building Science Corporation.)

     

    Right – If drip edge flashing is installed over fully adhered roof membrane at eaves, use flashing cement to seal the upper edge of the flashing.
    Figure 7. If drip edge flashing is installed over fully adhered roof membrane at the eaves, use flashing cement to seal the upper edge of the flashing. (Source: Building Science Corporation.)

     

    Right – Under metal roofing, sheathing is protected by metal edging over a fully adhered membrane and a slip sheet of loose laid building paper.
    Figure 8. Under metal roofing, sheathing is protected by metal edging over a fully adhered membrane and a slip sheet of loose laid building paper. (Source: Building Science Corporation.)

     

    Success
    Ensuring Success

    In high wind zones it is recommended – as a minimum requirement - that a fully adhered roof membrane underlayment be installed at roof eaves and roof rakes.

    Asphalt shingles that are installed at eaves should be installed over an asphalt shingle starter strip that is adhered to the fully adhered membrane underlayment, or to the drip edge, or both.

    Asphalt shingles that are installed at gables/rakes should be installed set in a minimum 8-inch-wide strip of flashing cement.

    Climate
    Climate

    IBHS Fortified Home Hurricane and High Wind Standards

    Drip Edge

    Drip edge must be installed (at eaves and rakes) with 3-in. laps. Drip edge shall extend ½ in. below sheathing and extend back on the roof a minimum of 2 in. Drip edge at eaves and at gable ends shall be installed over the underlayment. The drip edge shall be mechanically fastened to the roof deck at a maximum of 4 in. on center.  Note: For shingle roofs, starter strips must be adhered at the eave and rake. Either embed the starter strip in roofing cement or use self-adhered starter strips

    Training
    Right and Wrong Images
    Image
    Right – Install metal drip edge at roof edges in high wind and rain areas
    Right – Install metal drip edge at roof edges in high wind and rain areas
    Image
    Right – If drip edge flashing is installed over fully adhered roof membrane at eaves, use flashing cement to seal the upper edge of the flashing
    Right – If drip edge flashing is installed over fully adhered roof membrane at eaves, use flashing cement to seal the upper edge of the flashing
    Image
    Right – Under metal roofing, sheathing is protected by metal edging over a fully adhered membrane and a slip sheet of loose laid building paper
    Right – Under metal roofing, sheathing is protected by metal edging over a fully adhered membrane and a slip sheet of loose laid building paper
    Image
    Wrong – The roof sheathing was inadequately fastened and gave way causing the gable end wall to fail
    Wrong – The roof sheathing was inadequately fastened and gave way causing the gable end wall to fail
    Image
    Right – There is a self-sealing bituminous membrane installed at the valley of the roof prior to the roof felt
    Right – There is a self-sealing bituminous membrane installed at the valley of the roof prior to the roof felt
    Image
    Wrong – There is not a self-sealing bituminous membrane installed at the valley of the roof
    Wrong – There is not a self-sealing bituminous membrane installed at the valley of the roof
    Image
    Right – The roof membrane is fully adhered and deck seams are sealed so the membrane will not flutter and fail due to negative pressure from high winds
    Right – The roof membrane is fully adhered and deck seams are sealed so the membrane will not flutter and fail due to negative pressure from high winds
    Image
    Wrong – This roof membrane on a low slope roof is fluttering and may fail because it is not fully adhered and deck seams below are not sealed, allowing air to leak up into the assembly while the membrane is pulled up due to negative pressures from wind
    Wrong – This roof membrane on a low slope roof is fluttering and may fail because it is not fully adhered and deck seams below are not sealed, allowing air to leak up into the assembly while the membrane is pulled up due to negative pressures from wind
    Image
    Right – A fully adhered roof membrane provides thorough water and wind protection in this mountain top location.
    Right – A fully adhered roof membrane provides thorough water and wind protection in this mountain top location.
    Image
    Wrong – If roof membrane is not fully adhered, it can flutter and fail due to negative pressure from wind above and positive pressure from air leakage through roof deck below
    Wrong – If roof membrane is not fully adhered, it can flutter and fail due to negative pressure from wind above and positive pressure from air leakage through roof deck below
    Image
    Wrong – Roof underlayment is not fully adhered and roof deck seams are not sealed so roof is susceptible to high-wind events
    Wrong – Roof underlayment is not fully adhered and roof deck seams are not sealed so roof is susceptible to high-wind events
    Image
    Right – Roof underlayment is fully adhered and roof deck seams are sealed so roof is resistant to high-wind events
    Right – Roof underlayment is fully adhered and roof deck seams are sealed so roof is resistant to high-wind events
    Image
    Right – Under metal roofing, sheathing is protected by metal edging over a fully adhered membrane and a slip sheet of loose laid building paper
    Right – Under metal roofing, sheathing is protected by metal edging over a fully adhered membrane and a slip sheet of loose laid building paper
    Image
    Right – A roller helps the tape to adhere over seams in the deck sheathing
    Right – A roller helps the tape to adhere over seams in the deck sheathing
    Image
    Right - Metal drip edge on this south Florida CMU home protects the top of the fascia and edge of the roof deck from water, wind-blown rain and embers, and insects.
    Right - Metal drip edge on this south Florida CMU home protects the top of the fascia and edge of the roof deck from water, wind-blown rain and embers, and insects.
    Image
    Right - An unvented attic with no soffit vents, borate-treated fascia board, metal drip edge, and concrete block construction on this south Florida home help make it resistant to hurricanes, pests, and wind-born wildfire embers.
    Right - An unvented attic with no soffit vents, borate-treated fascia board, metal drip edge, and concrete block construction on this south Florida home help make it resistant to hurricanes, pests, and wind-born wildfire embers.
    Image
    Right – This hot-humid climate home employs several hurricane- and termite-resistant features including concrete block construction, borate-treated framing, a hip roof design with metal drip edge, impact-rated windows, and an unvented attic.
    Right – This hot-humid climate home employs several hurricane- and termite-resistant features including concrete block construction, borate-treated framing, a hip roof design with metal drip edge, impact-rated windows, and an unvented attic.
    Videos
    Publication Date
    Author(s)
    Guertin Mike
    Organization(s)
    Fine Homebuilding Magazine
    Description
    Video presentation explaining proper roof membrane and shingle installation, including key weak points where moisture can get in during a disaster weather event.
    CAD
    CAD Files
    IBHS Fortified Home Drip Edge Installation for Hurricanes
    IBHS Fortified Home Drip Edge Installation for Hurricanes
    Download: PDF
    IBHS Fortified Home Drip Edge Installation for Concrete and Clay Tile Roofs
    IBHS Fortified Home Drip Edge Installation for Concrete and Clay Tile Roofs
    Download: PDF
    IBHS Fortified Home Drip Edge Installation for High Winds
    IBHS Fortified Home Drip Edge Installation for High Winds
    Download: PDF
    IBHS Fortified Home Self-Adhered Membrane Roof Deck
    IBHS Fortified Home Self-Adhered Membrane Roof Deck
    Download: PDF
    Compliance

    Compliance

    The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

     

    ENERGY STAR Single-Family New Homes, Version 3/3.1 (Rev. 11)

    ENERGY STAR Single-Family New Homes requires that builders comply with the National Water Management System Builder Requirements which specifies water management details for roofs, walls, foundations, sites, and building materials.

    Please see the ENERGY STAR Single-Family New Homes Implementation Timeline for the program version and revision currently applicable in your state.

     

    DOE Zero Energy Ready Home (Revision 07)

    Exhibit 1 Mandatory Requirements.
    Exhibit 1, Item 1) Certified under the ENERGY STAR Qualified Homes Program or the ENERGY STAR Multifamily New Construction Program.

    Exhibit 1, Item 6) Certified under EPA Indoor airPLUS. See the EPA Indoor airPLUS checklist for additional building and site water management requirements.

    Visit the U.S. DOE Building Energy Codes Program to see what code has been adopted in each state.

     

    2018 and 2021 International Residential Code (IRC)

    R301.2.1 Wind design criteria. Buildings shall be constructed in accordance with the wind provisions of this code using the ultimate design wind speed in Table R301.2(1) as determined from Figure R301.2(5)A. Where not otherwise specified, the wind loads listed in Table R301.2(2) adjusted for height and exposure using Table R301.2(3) shall be used to determine design load performance requirements. The same requirements are given in the 2021 IRC, with changes only to the location of the referenced figures.

    Retrofit:  2009, 2012, 2015, 2018,  and 2021 IRC

    Section R102.7.1 Additions, alterations, or repairs. Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with the requirements of this code, unless otherwise stated. (See code for additional requirements and exceptions.)

    Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.

     

    IBHS Fortified Home Hurricane and High Wind Standards

    Drip Edge

    Drip edge must be installed (at eaves and rakes) with 3-in. laps. Drip edge shall extend ½ in. below sheathing and extend back on the roof a minimum of 2 in. Drip edge at eaves and at gable ends shall be installed over the underlayment. The drip edge shall be mechanically fastened to the roof deck at a maximum of 4 in. on center.  Note: For shingle roofs, starter strips must be adhered at the eave and rake. Either embed the starter strip in roofing cement or use self-adhered starter strips

     

     

    More

    More Info.

    Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

    References and Resources*
    Author(s)
    Insurance Institute for Business & Home Safety
    Organization(s)
    IBHS
    Publication Date
    Description
    Webpage providing video links and Spanish/English handouts for installing roofs to meet the hurricane and high wind resistant guidance in the IBHS Fortified Home criteria.
    *For non-dated media, such as websites, the date listed is the date accessed.
    Contributors to this Guide

    The following authors and organizations contributed to the content in this Guide.

    Building Science Corporation

    Last Updated

    Mobile Field Kit

    The Building America Field Kit allows you to save items to your profile for review or use on-site.

    Sign Up  or  Log In

    Did you find this information helpful?

    If you have questions and/or would like a reply to this feedback, please include your e-mail address in the message.
    This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.