Step flashing offers far better protection from leaks, because even if a single piece of step flashing fails, the water just hits the next lower piece. That flashing directs the water onto the shingle and the water drains down the roof. – Installing Shingles and Step Flashing – Cutting and Installing a Ridge Vent Tom Melillo, residential project manager, Roof Services: The main reason for a starter course is.
Keep water out of your home and running down the roof where it belongs with appropriate use of step flashing. Step flashing is used where a roof meets a wall, to cover the junction of those elements, preventing leaks. Flashing is a strip of metal, usually aluminum, about 8 inches long, and bent at 90 degrees with each side at least 5 inches wide. On a wall to be covered with wood, cement board, vinyl or metal siding, the step flashing, and associated roofing, must be installed first, so the siding can cover the top of the step flashing on the wall.
1
Slice along the bend line about 4 inches into the first piece of flashing at the bottom of the roof with tin snips.. Fold the roof side of the flashing down over the facing board along the roof line. Bend the vertical edge at about a 45-degree angle to make a tab to 'kick out' water, away from the wall and over the bottom of the roof. Nail the flashing to the wall with two galvanized roofing nails and a hammer.
2
Lay a shingle over the step flashing starting at the roof edge. Fasten that shingle with two galvanized nails at the top, then cover the top of it with another piece of step flashing, nailed to the wall. Work up the roof in steps, covering each end of flashing with a shingle and each end of a shingle with flashing, so there are no open seams. Alternate flashing and shingles to the roof peak.
3
Cut a piece of flashing along the bend line about half the length of the strip to flash the peak of the roof. Bend the roof edge of the flashing down over the peak and nail the wall side to the sheathing extending past the peak. Install a reverse peak flashing for the other side of the roof, so the two wall edges overlap in an 'X.' Nail step flashing at a peak so the roof side extends over peak flashing on the roof.
4
Cover both sides of the roof with step flashing and shingles from the eave to the peak. Caulk the joints of flashing at the peak.
5
Install siding on the walls down to the flashing. Leave a 1/4-inch gap between the step flashing and wood siding or cement board. Nail J-channel for vinyl or metal siding onto the flashing; follow the directions of the siding manufacturer for specific installation of these materials.
Things You Will Need
- Step flashing
- Tin snips
- Galvanized flashing nails
- Hammer
- Roof caulk or cement
- Shingles
- Siding (varies)
Tips
- Install roofing felt before starting step flashing. Run roofing felt up the wall about an inch higher than the wall side of the step flashing.
- If your house has a roof line that extends past a corner of two walls, make the first piece of step flashing a corner. Use tin snips to cut a piece of flashing at a 45-degree angle from the outside corner to the bend line. Fold the top part around the corner and nail it to both walls. Lay the other edge on the roof. Caulk the bend line, the angle cut and all other edges with roofing caulk or cement, then proceed with step flashing up the roof.
Warning
- Use caution when working on the roof. Batten boards or a harness can make it less hazardous.
References (7)
About the Author
Bob Haring has been a news writer and editor for more than 50 years, mostly with the Associated Press and then as executive editor of the Tulsa, Okla. 'World.' Since retiring he has written freelance stories and a weekly computer security column. Haring holds a Bachelor of Journalism from the University of Missouri.
Cite this Article Choose Citation Style
Haring, Bob. 'How to Install Step Flashing Under Siding.' Home Guides | SF Gate, http://homeguides.sfgate.com/install-step-flashing-under-siding-21255.html. Accessed 12 September 2019.
Haring, Bob. (n.d.). How to Install Step Flashing Under Siding. Home Guides | SF Gate. Retrieved from http://homeguides.sfgate.com/install-step-flashing-under-siding-21255.html
Haring, Bob. 'How to Install Step Flashing Under Siding' accessed September 12, 2019. http://homeguides.sfgate.com/install-step-flashing-under-siding-21255.html
Note: Depending on which text editor you're pasting into, you might have to add the italics to the site name.
- POST a QUESTION or READ FAQs about problems and leaks at roof-wall joint flashing locations
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Roof-wall flashing detail specifications & SNAFUs:
This article illustrates and discusses alternate or rather goofy attempts at roof-wall intersection flashing to prevent leaks & water damage and points out where leak risks may remain.
In our page top photo my grandson, Tanner Gilligan points out the white caulk that was installed as a stopgap measure where the builder has installed a bay window into a stuccoed wall without proper roof-wall flashing (red arrow).
Tanner would have also pointed out the horizontal flashing (orange arrow) had he not needed his other arm to hold on to the building.
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
Wall Flashing & Step Flashing Snarl-Ups to Avoid
This article series discusses best practices construction details for building exteriors, including water and air barriers, building flashing products & installation, wood siding material choices & installation, vinyl siding, stucco exteriors, building trim, exterior caulks and sealants, exterior building adhesives, and choices and application of exterior finishes on buildings: paints, stains.
Above we show a feeble attempt at flashing and counter flashing at the roof-wall intersection of a low slope roof. The installer tacked a row of asphalt shingles to the wall, caulked their top edge, and hoped for the best.
Proper Roof-Wall Flashing Example
To install the roof-wall flashing above the builder bent the top edge of the flashing into a 90-degree lip about 2 cm in width. That lip is then set into a reglet or groove, in this case cut into the mortar joint of the brick wall above. Above the flashing lip the groove is sealed with mortar or with a sealant to prevent water from running behind the flashing and to hold it in place.
Just below we illustrate a proper installation of flashing, in this case lead, installed at the abutment of a lower roof to a masonry wall on a building near Goodrich Castle in Ross on Wye in Herefordshire in the U.K.
Also see CAULKS & SEALANTS
More Questonable or Ugly Roof-Wall Flashing Examples
Below we illustrate that using a single piece of metal flashing where the uppermost edge of a shed-roof abuts a vertical building sidewall works fine, though the use of exposed nails (see our photo below) may form leak or wear points in the roof.
Below we discuss the very different case of the use of single-piece versus step flashing at the abutment of the side of a sloping roof to a building sidewall.
Re-Using Step Flashing When Re-Roofing?
At re-roofing time, when the old shingles are to be torn off, it's not always so easy to re-use the original step flashing that extends up under the building siding.
The new shingle courses have to line up exactly with the original shingle course/step flashing placement, the old step flashing is often bent-up during old shingle removal, making it hard to get the new shingles to lay flat.
As we see in our step flashing re-use at re-roofing time photo (left) the installer cut the new shingles too long so they have two reasons to be buckled, lifted, and vulnerable to wind-blown rain leaks at this building wall.
More Step Flashing Snarl ups
It's easy to get confused when installing step flashing, leading to lots of building leaks. Our step flashing snafu photos below demonstrate a few typical step flashing snarl ups.
At left our photo shows some interesting work. It looks as if someone re-sided the building and installed new counter flashing over a wood strip along the roof-wall intersection.
At least we hope the brown bent-over flashing also extends up under those clapboards.
But take a closer look (click to enlarge) and you'll see that the new roof shingles are out of step with the original step flashing, so that the flashing extends less than an inch on top of each shingle course, and the head of the flashing in some locations appears not very far at all under the shingle course above.
This installation looks questionable. Check inside for leaks.
Flashing against irregular sidewalls such as this up-state New York cabin (above left) can require some thought.
We'd need to use custom-formed lead counterflashing as is done on tile roofs, or cut a reglet into the wall deep enough to bend the counterflashing and hook it into the wall to keep wind-blown rain and wall run-down rain from moving behind this step flashing. Our second photo (above right) shows leak stains on the interior of the building wall where this detail was used.
Proper Roof-Wall Abutment Flashing Examples
Below are two photographs of roof-wall step flashing, completed and effective of a slate roof against a brick wall (below left), and in-process, with step flashing against a dormer sidewall before the dormer siding has been put in place (below right).
Also see FLASHING ROOF WALL DETAILS for more details about proper exterior wall flashing specifications.
Use of Continuous Single-piece Solid Metal Flashing vs. Step Flashing at Roof-Wall Abutments - Steep Slope Roofs?
Our photo shows the bottom end of a single-piece of (damaged) sloped-roof-wall flashing. In our OPINION it's not likely that this flashing installation will long resist any significant quantity of water at the lower roof edge, and both blowing wind and any backup due to gutters, ice, or snow will exacerbate the leak risk.
NRCA (Berg) points out that while continuous metal flashing is used at wall junctures in certain steep-slope roof installations, special flashing installation details are required that are different from a step-flashing sealed roof, and even when installed according to specifications, this approach can leave the roof vulnerable to leaks or moisture damage from wind-driven rain.
If single piece flashing is to be used, according to Mr. Berg, [paraphrasing]
- The flashing needs to be installed before installing the roof shingles
- The metal flashing is formed with a hook edge and cleated on 12' centers
- The flashing extends up the wall at least 4'
- The flashing extends onto the roof a minimum of 2 inches - 4 inches is preferable in more severe climate areas.
- Flashing joints are lapped 6' in the direction of water flow
- Building siding material and roofing felt on the building vertical wall may serve as counterflashing [this is true also with the step flashing method if installed at original construction]
- The shingles are sealed to the metal flashing with plastic cement to attempt to reduce wind-driven rain penetration, however as this sealing may separate from the material the single-piece flashing approach again becomes vulnerable to leakage
Berg continues that 'Because the hook edge and cleats tend to raise the shingles above the flashing, the detail is somewhat vulnerable to wind-driven rain and from moisture trapped in debris that may accumulate in lower areas of the flashing'.
OPINION: DF: inspecting thousands of residential properties we have encountered quite a few attempts to use a single piece of metal flashing instead of step flashing at roof-wall abutments, virtually never installed according even to the not-entirely-reliable NRCA recommendations above.
And in our experience, when a single piece of flashing extends only a few inches under the shingles, especially on a long roof slope, and worse on a roof that happens to slope slightly towards rather than away from the abutting vertical building wall, the accumulated roof drainage water near the bottom end of the roof-wall intersection will overwhelm the width of the flashing and, because it is not directed back out on top of successive shingle courses, it leaks into the building or building wall.
In sum, single piece roof-wall flashing is a bad idea in the hands of typical residential roofers and re-roofers, and this approach has been found by home inspectors to be unreliable in practice.
This article is an addendum to FLASHING ROOF WALL DETAILS [live link just below] adapted from BEST ROOFING PRACTICES.
...
Continue reading at FLASHING ROOF WALL DETAILS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Or see FLASHING on BUILDINGS - home
FLASHING WALL DETAILS for building walls
Suggested citation for this web page
FLASHING ROOF-WALL SNAFU at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.
INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING FLASHING
Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia
Share this article
...
Ask a Question or Search InspectApedia
Questions & answers or comments about problems and leaks at roof-wall joint flashing locations.
Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References
- InspectAPedia.com® - Daniel Friedman - Publisher & Editor.
- Steve Bliss's Building Advisor at buildingadvisor.com helps homeowners & contractors plan & complete successful building & remodeling projects: buying land, site work, building design, cost estimating, materials & components, & project management through complete construction. Email: [email protected]
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com - InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also include a list of recommended books for the specific article topic as well as other references, and information sources.
- Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
- Additional technical contributors & reference sources for this article are listed below.
- Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
- Paul Galow - technical consultant on networking, LAN design, applications support. Galow Consulting Services, 914-204-1749, email: [email protected]
- John Rudy, Advantage Home Inspections, Flemington N.J. 08822 home inspector, 908-806- 6364, Home, Radon & Termite Inspections, Central & Parts of North New Jersey, email: [email protected]
- 'Flashing: the plain solution to leaky walls', Thomas E. Remmele, Manager, Technical Services, Sto Corporation, Building Standards, November/December 1999 p. 21-25.
- NRCA - National Roofing Contractors Association - http://www.nrca.net/, 10255 W. Higgins Road, Suite 600, Rosemont, IL 60018-5607, Tel: (847) 299-9070 Fax: (847) 299-1183
- 'Continuous metal vs. step flashing in steep-slope roofing', Donald Berg, P.E., Professional Roofing (NRCA), June 1993, p. 57.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
- Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
- Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
- The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for this article. All rights and contents are ©Journal of Light Construction and may not be reproduced in any form.
- ...
- Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: [email protected]. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page 'Promo/Redemption' space. - TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page 'Promo/Redemption' space.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
- The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page 'Promo/Redemption' space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones.
Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page 'Promo/Redemption' space.
Building inspection education & report writing systems from Carson, Dunlop & Associates Ltd - Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page 'Promo/Redemption' space. InspectAPedia.com editor Daniel Friedman is a contributing author. - The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones