How To Add A Bay Window To Your House

Synopsis: The add-on of a bay window can make a room or business firm seem like an entirely new place. In this starting time of a two-function article, veteran architect Rick Arnold outlines his procedure for installing a bay window in an existing house. For Arnold, the key to a smooth process is building the roof first. The roof is then installed in one piece on top of the bay window. The procedure for building the roof proceeds through several steps. Commencement, make a template for the roof base of operations. So, create a rafter nailer from the template. After the rafter nailer is washed, lay out and fasten the common rafter, then lay out and fasten the hip rafters. After the hip rafters are in place, the jack rafters go in. The final construction step before the roof is installed is the laying out and cutting of the capsule. This commodity includes sidebars on choosing a bay window and using a construction calculator to figure dimensions. The article also includes a diversity of technical drawings that illustrate how to determine the cuts for the template and the capsule.

Part two of this article is bachelor here.

Magazine extra: Spotter this video series for Rick Arnold's method of building a bay-window roof.

I recently helped my mom and stepdad move into a pocket-sized ranch house so that they'd be free of stairs and have an easier time getting effectually. The small-scale house was in decent shape and livable, but the north-facing bedroom's lack of light made the infinite grim. With my stepdad's increasing mobility problems, it seemed likely that he'd be spending more and more fourth dimension in there, then I decided to make the room more inviting by swapping the existing window for a projecting bay window.

Installing a bay window is one of the easiest ways to transform a room. By reaching beyond a dwelling's wall, a bay window gathers light from three directions, creating an inviting, sunday-collecting space that is perfect for displaying plants, cozying upwardly with a good book, and brightening dark interior spaces.

Not surprisingly, installing a bay window is more involved than putting in a conventional window. This first part of a ii-office commodity deals with choosing a window and framing a good-looking roof to embrace information technology—ahead of fourth dimension. It may seem odd to frame the roof first, simply it makes the whole project easier. The second part covers installing the window, making it weathertight, and trimming the exterior.

Bay-Window Nuts

The most common bay windows have exterior corners that meet at a 45° bending, merely other styles are available. Fortunately, the installation methods for all types and sizes are similar. Bay windows are by and large sold with head and seat boards that concur the window together and form its acme and lesser. You also can get them without caput and seat boards for installation in angled or curved walls. The 45° window that is featured here with head and seat boards is the near common type of window installed. I chose the narrowest window model that was available from this manufacturer so that the window wouldn't overwhelm the small bedroom.

Why Build The Roof First?

Through the years, I've learned that when a projecting window needs a roof, it's better to build the roof get-go. For starters, it's easier and safer to build the roof on the ground. In addition, having the roof framed even so removable makes it easier to cut back brick or siding for flashing and to integrate the window into the house. It also means that the house is vulnerable to bad weather for less fourth dimension.

If you've ever seen a bay window that just doesn't look right, it might be because its roof has the wrong shape. The proper shape for a 45° window like the one featured here is based on a section of an octagonal roof with 22.v° hip rafters.

At this bending, the hip rafters bifurcate the window's forepart corners, giving the roof a pleasing shape. The pitch of the roof is also an of import factor. When I'm installing the roof in a gable stop, I like to utilise a steep pitch then that the roof has enough mass to remainder the surrounding wall. For this window's overhang, I added 4-1⁄ii in. to the roof framing for a finished soffit made from a i×5 lath. A five -in. soffit works with almost bay windows, but larger windows (8 ft. broad or more) may need wider soffits to match the overhang on the house'south main roof amend.

When deciding on a pitch and overhang for your window, be sure to consider architectural features such as other windows and house-roof overhangs that could interfere with the window'south roof. Once you accept a proposed pattern, make a sketch to come across how it volition await on the building. This roof'southward 12-in-12 pitch also complements the window's squarish shape.

Brand A Template

I've seen these little roofs challenge fifty-fifty veteran framers, simply my design method makes them piece of cake to build. The first matter that I do is copy the shape of the window (in plan view) onto a piece of 3⁄4-in. OSB. I use this OSB template to lay out and cutting the 2x4s that form the roof's ceiling joists and subfascia. I call this assembly the base. One time I have the base, I rework the template into a nailer for attaching the rafters.

To brand the template, I snap a line on the window'due south plywood headboard indicating the 4 in. that extends into the rough opening. Then I transfer the window'southward shape to the template. Using a scrap of stock, I add the overhang's width to the template and cut out the trapezoid-shaped OSB with a round saw. Then I cut and get together the ceiling joists and subfascia on top of the template.

I fasten the components with two-1⁄two-in. screws. I utilise screws because they allow me to hold the components with one mitt while I fasten with the other mitt. The screws hold meliorate, too. This detail is important because the roof may exist lifted onto the window and removed several times before it's put in place for the last fourth dimension.

Make A Nailer For The Rafters

After the base is done, I rework the template into a nailer for the rafters. The rafters attach along the nailer's top edge; the whole assembly then is fastened to the business firm. If you're using the manufacturer'south cable-break system to help acquit the weight of the projecting window, the zipper bracket can be mounted on this OSB nailer, making the entire window installation easier.

You might assume the sides of the nailer are 45° similar the sides of the base, but they're not. They're slightly less. In simple terms, it'southward because the roof is based on a segment of an octagon, not a box.

The correct shape for the nailer is critical, and the math is somewhat complicated. I brand it like shooting fish in a barrel by using a play a joke on I learned years ago (run across "Fashion a rafter nailer from the template," p. 40).

Cut And Fit The Rafters

Before I take rafter measurements, I make sure that the rafter nailer is perpendicular to the base. If it isn't, I push or pull it until information technology is; so I caryatid information technology in the proper position. The first rafter I cut is the common rafter. I measure from the outside edge of the nailer to the outside border of the subfascia. Considering the roof will have a 12-in-12 pitch, the mutual rafter will have a 45° cut on each terminate. After I screw the common rafter in place, I measure out for the two side by side hip rafters. They're longer than the mutual rafter, so they'll have slightly different angles. With a 12-in-12 roof, the hips will exist 43° on the top and 47° on the bottom.

Getting the hips to fit correctly is important. I propose existence cautious when you cut; you tin can always trim them if they're likewise long. If the hips are as well short, the sheathing won't fit correctly, and so it'southward better to make a second cut than cut them too short the first time.

The hips bisect the 45° sides of the window, so the tops get a 22.5° bevel. Later I check the fit, I utilize this first rafter every bit a template for the next rafter. I line it up and mark the bottom, and then mark the bevel end. I keep it oriented the same way when I cutting the rafter. Now I have a right and a left bevel.

The final pair of rafters go from the center of the angled subfascia to the center of the angled side on the rafter nailer. These are the jack rafters. They will have 45° angles on both ends and a 45° bevel at the top. Considering the other side volition be the same length, I use the outset one as a template to mark the second.

Cut The Capsule

With the rafters done, I cut the sheathing for the roof. I don't install it, however, because that would interfere with installing the stainless-steel cables that assist to support the window. The second half of this ii-office article will show how to install the cables.

To mensurate for the heart piece, I outset measure the fascia length. Then I measure the height. Finally, I measure the width at the superlative. To cut the center console, I transfer the fascia measurement to the panel edge and mark its centre. I employ a framing foursquare to ensure that the height measurement is perpendicular to the edge of the sheathing. And so I transfer the summit measurement to the capsule, centering it on the perpendicular line and using a square to form a correct angle at the peak.

To cut the side pieces of sheathing, I measure along the subfascia; then I measure the hip rafter and the length along the top of the nailer. I extend the tape to the imaginary indicate where the sheathing meets the building.

To lay out the triangular-shaped pieces of roof sheathing, I transfer the subfascia measurement to the edge of the console. At opposite ends of the fascia measurement, I transfer the hip rafter and nailer measurements up. At the stop of both measurements, I make a small arc past property a pencil at the end of the tape. Where the 2 arcs intersect is the point at the top.

In part 2 of this commodity, I'll show you how to install the bay window, put on the roof, and integrate the whole window assembly into the wall.

Make A Template For The Roof Base


Measure out the width and project. Begin making a template for laying out the ceiling joist and subfascia past copying the shape of the window onto a sheet of three⁄4-in. OSB. ane When making the template, don't include the 4 in. of plywood that extends into the rough opening.	Add together the overhang. Draw the window shape onto the OSB template, and add the 4-ane⁄2-in. roof overhang to the front and sides of the template.

Fashion A Rafter Nailer From The Template


1. Subsequently cutting out and using the template to lay out and assemble the roof base of operations, you tin catechumen the template into a nailer for attaching the rafters.	2. Hook a tape on the template corner to measure the angled side. Swing an arc the length of the angled side on the template.


iii. Use a square to transfer the mark across the template.	4. Connect the outside corner to the new mark with a straightedge.


5. Repeat the procedure on the other side of the template, and cut out the shape. Trim 1⁄two in. from the bottom border of the nailer with a round saw.	Without trimming, the nailer would projection beyond the subfascia, preventing the sheathing and finished fascia from sitting flat. After trimming, the nailer should fit on the base so that the forepart side is flush with the subfascia (photo in a higher place).

Lay Out And Fasten The Common Rafter


Mensurate the common rafter. Later on using a framing square to ensure that the rafter nailer is perpendicular to the base (caryatid if necessary), measure from the elevation of the nailer (front end side) to the outside edge of the subfascia. This volition exist the long side of the rafter. Cut 45° miters on both ends.	Fasten with screws. Drive 2 ane⁄two-in. drywall screws through the rafter cease and into the roof base of operations. At the top of the rafter, drive screws from the back side of the nailer into the rafter. Screws concur improve than nails; this is important, because the roof volition likely exist moved several times before last installation on the window.

Lay Out And Fasten The Hip Rafters


Measure the hips. The hip rafters run from the top corners of the rafter nailer to the outside corners of the subfascia. Record the measurement, then subtract iii⁄8 in. to lower the rafter corners so that they are in airplane with the subfascia.	Mark the cuts. Hip rafters on 45° bay-window roofs with a 12-in-12 pitch will have 43° cuts at the superlative and 47° cuts on the lesser. For pitches other than 12-in-12, apply a construction calculator (sidebar left) to figure the angles.


Chemical compound cutting on the top; miter cutting on the bottom. The bottoms of the hip rafters get a 47° miter without a bevel, but the tops need a 22.5° bevel in add-on to a 43° miter. Tilt the saw to 22.five°, and follow the line made before.	Bank check the fit. Confirm that the first hip rafter fits correctly, then utilise information technology as a template to cutting the other side. Bundled correctly, the bevels should form a point when the rafters are stacked. If not, the second bevel is sloping the incorrect way.

The perfect fit. The rafters shouldn't protrude beyond the top of the rafter nailer or the subfascia. If the rafters are proud, the sheathing, which will be installed later, won't fit tight to the framing. If the rafters stick up slightly, trim their length from either end, using the same saw settings as the original cut.

Using A Construction Estimator

Kickoff, mensurate the height of the rafter nailer. Enter the number and press rise. Next, measure the rafter length, enter that number, and press diagonal. Finally, printing the pitch button. The result is the top angle. Round that number to the nearest degree, and subtract it from xc to get the bottom bending.

Lay Out And Spike The Jack Rafters

Cut and fit the jacks. Holding the tape perpendicular to the subfascia, measure to the front of the nailer and the top of the subfascia. The bottom cut has a 45° miter only. The peak cut has a 45° miter and a 45° bevel. After checking the fit, employ the rafter as a template for the other side by stacking the pair of rafters with 1 on top of the other as described on the facing folio.

Lay Out And Cut The Sheathing

Center Sheathing


i. Transfer the fascia measurement to the panel edge, then find and marker the center of this measurement. 2. Use a square to depict a perpendicular line from this mark.	3. Measure the height, and transfer this measurement to the perpendicular line in the center. 4. Measure the width at the summit. Bisect this measurement on the vertical perpendicular line.

5. Connect the ends of the lines. Cut out the shape with a circular saw, but don't attach the sheathing.

5. Connect the ends of the lines. Cut out the shape with a round saw, just don't adhere the sheathing.

Center Sheathing

Side Capsule


1. Measure the fascia edge, and transfer the measurement to the edge of the sheathing panel. 2. Mensurate the side on the rafter nailer, and transfer this measurement to the sheathing by forming an arc at the stop of the tape.	3. Do the aforementioned for the hip rafter.

4. The intersection of the two arcs is the point at the top. 5. Connect this point to both ends of the fascia measurement, cut out the shape with a circular saw, and use the first piece as a template for the other side.

4. The intersection of the 2 arcs is the point at the top.
v. Connect this signal to both ends of the fascia measurement, cutting out the shape
with a round saw, and use the first piece every bit a template for the other side.

Side Sheathing

Up Next: A Weatherproof Installation

In the 2nd half of this two-office article, we'll tackle preparing the bay-window opening, installing the window unit with its cable-support system, and integrating the new window and its roof with the surrounding wall.