Bay window is an excellent feature for any house. Unfortunately for do-it-yourselfers, any bay window should include a bay window roof. If you want to have a bay window in your home, you better need to know how to frame a bay window roof.

The bay window roof may be an extremely attractive feature to your home’s façade, however, it does require a bit more effort and technical expertise to build, particularly when it comes to planning out and constructing the roof structure. However, it is still a task that can be completed entirely by yourself. 

Then, why are you waiting? Get into this article and know better about framing a bay window roof.

How To Frame A Bay Window Roof

Bay windows allow in more sunlight and offer a spectacular perspective from the outside environment. However, while constructing, installing, and maintaining one, you must ensure that nothing leaks and you get the maximum from it.

And, to get the best, you need to follow a step-by-step guideline. And, you’ll find all the details below in this article.

Frame A Bay Window Roof

Bay Window Roofing Materials

Remember that before you begin working on the bay window, you’ll have to gather all of the essential tools and equipment. Having all the appropriate tools in hand makes things easier to do. Here are all the important tools you’ll need;

  • Plywood
  • Roofing nails
  • Drill
  • Circular saw
  • Drip cap
  • Exterior casing
  • Casing nails
  • Stapler
  • Staples
  • Hammer
  • Screwdriver
  • Measuring tape
  • Flat prybar
  • Flashing
  • Caulk
  • Caulk gun
  • Gloves, goggles, and ear protectors for working with drill, hammer, and saw.

The procedure of Framing A Bay Window Roof

Framing the bay window roof is very simple. You need to follow some steps and then you’ll have your bay window roof ready. The steps are here,

Layout and installation of the Bay Window

Before framing the bay window roof, you must first install the bay window. After that, plan carefully and check with the design blueprints.

Make sure the window frame, window, and window cap are all in place and safe. And they are also insulated. Once you’ve confirmed that all of those are alright, you may begin constructing the roof.

Design The Roof

The bay window ought to have been included in your initial ideas for the bay window roof. A bay window roof is generally a sloping roof built with 45-degree angles that extend out with multiple facets. At this point, you should design the roof superstructure. 

Building a bay roof may be extremely difficult; even an expert roof framer would frequently resort to experimenting with the cut and fit of the parts necessary for a bay roof. However, this problem can be solved by using an online calculator. 

There are several workable frame calculators accessible online for drafting your plans. You can get an auto-generated diagram with the lengths as well as angles. You’ll need to enter the measurements and dimensions, those you’re operating within the calculator.

Construction Of The Frame

To begin constructing the bay window roof structure, attach a 2 by 6 foundation panel to the rear wall. Long nails may also be used to fasten the panel even more firmly. 

Then, build the roof’s edge using the 2 by 6 sub-fascia panels. Cut the trusses to size using your circular saw, and using the table from the roof structure calculator as a reference. Then nail them firmly into place. 

Always use safety gloves and goggles when using the saw for precaution. And it’s also advisable to wear these while hammering the nails into position. 

Lastly, fill up the structure with batt insulation which is made of fiberglass, and cover it with plywood.

Finishing Touch

Once you’ve built the bay window roof structure, insulated it, sealed it, and coated it with plywood, it’s time to put the finishing touches on it. 

Build a drip line and flashing so that rainfall and snow may securely flow off the roof instead of sliding down the window glass.

Then, attach roofing shingles across the whole roof in single overlapped sheets.


So, this is all about framing the bay window roof and hope that you’ve understood how to frame a bay window roof. No more waiting. It’s time to frame your bay window roof.

Don’t forget to wear safety gear. Enjoy nature from your bay window. All the best to you.


As a civil engineer and roofer, I love to share the experience that I have gained through the last couple of years. In the roofing industry, practical experience is a very crucial fact that can help you a lot. Hence, I want to help you with my blog.

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