FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Fine Homebuilding Project Guides

Windows & Doors

Guide Home
  • Choosing Windows
  • Installing Windows In New Walls
  • Retrofitting Windows
  • Window Repairs
  • Door Basics
  • Interior Doors
  • Exterior Doors
How-To

Making Head Flashing

Bending metal for simple flashings requires a few basic cutting tools and a siding (or aluminum) brake.

By Andy Engel Issue 261 - Aug/Sept 2016
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Every window and door needs head flashing, and bending metal for these simple flashings is a gateway to the skills needed to make other wall and roof flashings. You probably already have the necessary cutting tools: a square, a utility knife, and snips. You also need hand benders and a brake (often called a siding brake or an aluminum brake).

The metal flashing used for this project is often called coil stock. It is sold in rolls in a variety of lengths, widths, thicknesses, and metals. Aluminum flashing—either bare (mill finish) or painted—is most common, followed by copper and galvanized steel. Lead-coated copper is also available and should be used when copper is placed below exposed cedar because tannins leaching from cedar corrode copper. Aluminum’s thickness is measured in thousandths of an inch, with 0.019 in. and 0.024 in. being common. Heavier aluminum with thicknesses of 0.027 in. and up is often referred to as gutter coil, because it’s also used to form seamless gutters. Copper’s thickness is measured by weight, with 16 oz. per sq. ft. being typical. Galvanized steel is measured by gauge, with smaller numbers corresponding to thicker material.

Thicker flashing material is more durable and more resistant to buckling from thermal expansion than thinner material; however, it also is more expensive and more difficult to bend. Siding brakes typically can bend aluminum up to 0.027 in. thick, copper up to 16 oz. or 24 oz., and galvanized steel up to 26 ga. or 28 ga.

Launch the slideshow below to follow step by step.

The first step in bending metal flashing is measuring what you want to flash. To find the width of the metal needed in the case of a head flashing, I measure how far the jamb or casing protrudes from the wall sheathing. To that, I add 1⁄8 in. because the bend will consume some material width. The wall leg should extend at least 2 in. up the wall. Finally, I add something for the leg that turns down over the face of the casing or jamb. I like to extend that about 3⁄8 in. down, but because I hem that edge, I allow a total of 3⁄4 in.

Hemming is when the edge of a piece of flashing is bent back on itself and flattened. This creates a straight edge that’s less likely to wrinkle. Additionally, cut edges of sheet metal are surprisingly sharp. Hemming folds the cut edge behind the face of the flashing and places the dull, folded edge out where people are most likely to be. To find the length of the metal, add 1 in. (to allow for each end to be folded) to the width of the jamb or casing. Cutting metal to length is simple. Use snips, or score the material with a sharp utility knife guided by a square, then bend along the score until it breaks.

 

021261090_08-head-flashing
Siding or aluminum brakes come in lengths from 4 ft. to 101⁄2 ft. Photos courtesy of Van Mark Products
021261090_09-head-flashing
Hand bender and common straight-cut aviation snips. Photo by Dan Thornton.

Bending and cutting tools
Siding or aluminum brakes come in lengths from 4 ft. to 101⁄2 ft. Brakes cost $1000 and up, but they can be rented for around $60 a day. Accessories are available to aid in cutting and rolling out coil stock. Hand benders cost around $20. Some models have replaceable jaws of various lengths so that they can be adapted to the job at hand. Snips come in a variety of forms. The ones shown here are common straight-cut aviation snips. Left- and right-cutting snips are also available to ease curved cuts. Snips cost about $15.


Andy Engel is a senior editor. Technical advice was provided by Tom Struble, a siding contractor in West Milford, N.J. Photos by Rodney Diaz, except where noted.

Fine Homebuilding Recommended Products

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

8067 All-Weather Flashing Tape

Available in 2- to 12-in. widths, this is a good general-purpose flashing tape that sticks well to most things. It features a two-piece release paper, water-shedding layers, and good UV resistance.
Buy at Amazon

Affordable IR Camera

This camera is super useful for tracking down air leaks in buildings. The one-hand pistol grip arrangement frees your other hand for steadying yourself while maneuvering tricky job sites.
Buy at Amazon

Handy Heat Gun

This heat gun is great for drying joint compound, primer and paint when patching drywall and plaster walls. Plus it can soften adhesive, get a very cold small engine to start, and shrink heat-shrink tubing.
Buy at Amazon
Previous: Nesting Casement Window Handles Next: Soldering Copper Cap Flashing

Guide

Windows & Doors

Chapter

Installing Windows In New Walls

Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Windows & Doors

Windows & Doors

Trusted, comprehensive guidance from the pros for choosing, installing, replacing, and repairing windows and doors on any house

View Project Guide

View All Project Guides »

Become a member and get unlimited site access, including the Windows & Doors Project Guide.

Start Free Trial

Choosing Windows
  • Window Types
  • Design and Materials
  • Energy-Efficient Windows
Installing Windows In New Walls
  • Installation, Start to Finish
  • Head Flashing for Windows
  • Video Series: Nail-Fin Window over Zip System Sheathing
  • Video Series: Nail-Fin Window over Exterior Rigid-Foam Insulation
  • Video Series: Nail-Fin Window over Housewrap
  • Video Series: Nail-Fin Window over Peel-and-Stick Housewrap
  • Video Series: Nail-Fin Window over a Fluid-Applied WRB
  • Video Series: Weatherproof Window Installation
Retrofitting Windows
  • Removing the Old, Installing the New
  • Video Series: How to Replace a Window
  • Video Series: Install a Full-Frame Replacement Window in a Brick Wall
  • Video Series: Install an Insert Replacement Window in a Brick Wall
  • Video Series: Retrofit a Flanged Window
Window Repairs
  • Restoring Old Windows
  • Repairs and Upgrades
Door Basics
  • Tools & Jigs for Door Hanging
  • How to Install Doors
  • Hinges
  • Handles, Knobs, and Locksets
  • Fixing Door Problems
Interior Doors
  • Prehung Doors
  • Pocket Doors
  • Other Types of Doors
  • Custom-Built Doors
Exterior Doors
  • Door Choices and Design
  • Installing Entry Doors
  • Building Exterior Doors
  • Installing French Doors
  • Replacing a Door
  • Adding Weatherstripping and Sweeps

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data