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

Flashing on a Curve

With modern flashing tapes, a metal head flashing isn't needed on an arched window—but there are ways to make one if you want to.

Issue 222
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles
SureSill

Q:

I need to install a curvetop vinyl window. What is the best way to flash the window at the top?

Bob Hazard, Newhall, CA

A:

Editorial adviser, Mike Guertin, responds: The approach I take depends on whether the window is flanged, whether it has additional casing around it, or whether the head has to be flashed with metal (for architectural reasons or personal preference).

Most flanged curve-top windows can be flashed with flexible self-adhering tape without an additional flashing.

Curved windows without a flange or flanged windows with a separate casing need flashing. I like to use flexible Z-flashings. Some have wall legs that are notched; they need additional steps to make them watertight. Other flexible flashings, like SureSill’s HeadFlash-Flex (www.suresill.com) and Astro Plastics’ Astro Flashing (www.astroplastics.com) have wall legs that fan out to the wall. There are nuances to installing flexible flashings, and manufacturers’ instructions will help you there. Don’t apply asphalt-based selfadhering flashing tape over the wall leg of flexible flashings unless the manufacturer approves it. The asphalt can react with additives that make the plastic flashing flexible. Instead, use a butyl-based selfadhering flashing tape.

Finally, you have a few options for curved metal cap flashings. If roll lead flashing is available in your area, hammer-form it to match the curve of a window head. Rather than using the window head as a form, cut a duplicate circular segment from a piece of plywood or OSB. Stack a couple of sheets to reach the same depth that the window frame or head trim projects from the wall surface. Hammer-form the lead using a block of hardwood to spread the blows to a larger area and to minimize cracking the lead.

When I have a batch of windows to flash with metal and the designer doesn’t want lead, I make a template of the curve from a piece of cardboard and have a local metal shop fabricate pieces from copper, bronze, or stainless steel.

For one window, I make my own flashing from copper or lead-coated copper. First, bend the flashing on a sheet-metal brake for the desired drip-leg, cap, and wall-leg dimensions. Make a plywood or OSB form to match the window-head curve. Snip a series of equally spaced cuts in the wall leg, closer together for short-radius curves and farther apart for long-radius curves. Bend the metal flashing around the form, and clamp it so that the wall-leg sections lie flat against the backing sheet. Cut V-shaped cards that are about an inch larger than the notch voids that are left at the wall-leg cuts. Make 90° bends about 1⁄2 in. in from the tip of the V-cards, and center a card over each notch void. Clamp the cards and flashing to the backing sheet; any warp in the wall leg will prevent the flashing from lying flat to the wall or the head of the window. Solder the V-cards to the flashing, and buff the finished product before installing.

Previous: Drip Cap Design and Installation Next: Part 1: Prepare a Rough Opening for a Nail-Fin Window over Zip System Sheathing

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