| Home | Wiring | Plumbing | Kitchen/Bath |
|
A large bay window creates a bright alcove for dining, reading, or visiting. The structure that is shown at right consists of a cantilevered platform and a knee wall supporting a pre fabricated window. Ready-made bay windows, which are available in many heights, widths, and depths, come complete with glass, trim, and ceiling. Some of them include easy-to-install roofs. The height you choose depends in part on the ceiling height in your house and the depth of the header that is necessary to span the bay opening. ---Two Types of Framing: Before deciding to add a bay window, ex amine the floor joists in the house. If there are no studs alongside the joists, the house has platform framing and you can add a bay window without hesitation. Studs along side floor joists signal balloon framing, which bars the installation of a bay window unless the ceiling height is 9 feet or more. ---Support for a Bay: In many in stances, no foundation is necessary for a bay window; simply extend the floor joists to make a cantilevered platform. However, if your house has a crawlspace rather than a basement, the work will be cramped and you may prefer to build a foundation for the bay. And a house that is built on a slab requires similar underpinnings. ---Building Skills: Usually, installing a bay window demands only basic carpentry and masonry skills, and requires only the tools and materials that are common to those trades (below) for the entire process. One exception is a house with a solid-masonry wall. Unless you are experienced in heavy masonry work, you might need the help of a professional. Get help also if you plan a bay window for a house of post-and-beam construction or closer than 4 feet from a corner of any house. In both cases special precautions are needed to avoid weakening the house structure. CAUTION---Wall materials sometimes contain asbestos or lead. Before cutting into your house, see advice on dealing with these hazards. == TOOLS:
= = = = MATERIALS:
SAFETY TIPS: Hammering and sawing can produce loud noises and flying debris. Protect your eyes with goggles, ears with earplugs, and lungs with a dust mask. TWO WAYS TO FRAME A BAY Redirecting joists. 23--- Where existing floor joists run parallel to the exterior wall , the bay joists run at right angles to the house joists, which are cut away and rein forced. Extending joists. In the installation shown at left, where the floor joists in the house run perpendicular to the exterior wall, bay joists are simple extensions spliced to the floor joists. CLEARING THE WAY FOR CANTILEVERS 1. Laying out the rough opening. 24--- • On the baseboard inside the house, mark the width of the bay-window rough opening, as specified by the manufacturer. • With a plumb bob steadied by a helper, transfer the two marks to the top of the wall. • Drill through the wall at all four points to mark the width of the opening on the outside. • In platform framing, remove the baseboard and cut away the wallboard from floor to ceiling between the studs that bracket the drilled holes. In balloon framing, extend the opening an additional stud space on either side. • Mark the width of the rough opening on the sole plate of the wall or, if you have balloon framing, on the floor. 2. Removing the siding. • Snap vertical chalked lines on the house siding, linking the holes that you drilled in Step 1; then snap a horizontal chalked line between the two top holes. • Cut through the siding along these lines with a circular saw set to the thickness of the siding. Use a carbide-tipped blade to avoid damaging the saw in case you hit a nail. For a house with brick veneer, use a masonry blade. • Within the cuts you have made, pull the siding or bricks from the wall. 3. Exposing the floor joists. • Measure the total thickness of the flooring in the house; add it to the distance above the floor of the lower holes drilled in Step 1. Transfer the sum to the sheathing, measuring down from the two holes . • Snap a chalk line between the marks. • Set a circular saw to the thickness of the sheathing and cut along the line. • Extend the saw blade and cut the sheathing vertically at the ends. • Pry off the resulting strip of sheathing to expose the band joist. Reset the saw to cut 1.25 inches deeper and cut through the band joist at both sides of the opening. • Working from the basement with a 0.5-pound maul, knock out the section of band joist between the cuts. A PLATFORM OF EXTENDED JOISTS Extending the bay joists. 25--- • When floor joists run perpendicular to the wall, mark each joist within the rough opening at a point twice the depth of the bay . • From lumber matching the floor joists, cut joist extensions three times the depth of the bay plus 6 inches. • Working outside, slide the extensions through the wall opening, hammering if necessary, and align their inner ends with the marks on the floor joists. If the house is balloon framed, avoid studs alongside joists by placing the extensions on the sides of the joists away from the studs. • Fasten the extensions to the joists with 3 inches in a zigzag pattern. If your house has I-beam joists , install wood filler between the flanges to fill the space between the web and the ex tension. Drive two rows of 3-inch nails every 6 inches through the web and into the filler and extension; clinch exposed nail points by hammering them flat. Cut I-beam or lumber blocking panels, and nail them to the sill plate between the joists. = = = TRICKS OF THE TRADE: Cutting a Board Square Place a framing square on the piece of lumber that you wish to cut and pencil a cut line. Align the saw blade with the pencil mark and place the square against the side of the saw’s shoe plate and the edge of the board. Grip the square firmly and cut along the pencil line, using the square as a guide. = = = REDIRECTING JOISTS 1. Marking joists for cutting. 26--- • Where joists run parallel to the wall, use a framing square to mark the width of the rough opening on the floor joist that is nearest the basement wall . • Extend the marks across the bottoms of the joists to twice the depth of the bay. 2. Reinforcing a joist. • Strengthen the joist next to those marked for cutting by nailing a reinforcement joist to it with 3 nails every 10 inches in a zigzag pattern. • To keep joists in alignment, nail blocking between the reinforced joist and the next joist away from the wall. If your house has I-beams, use another I-beam as reinforcement . Fill the space between the webs with wood and secure the beams with two rows of nails positioned every 6 inches. Clinch exposed nail points. 3. Supporting the floor. As a temporary support, place shoring 2 feet beyond the opening in the band joist, placing the posts beneath the reinforced joist and the joist nearest the basement wall. • Lay 4-by-4 top and bottom plates under the joists; use a plumb bob to mark the plates for post locations. • Toenail 4-by-4 support posts to the top plates at the marks. • Raise the assemblies onto the bottom plates, plumb and shim them at the joists for a tight fit, then toenail the posts to the bottom plates. 4. Cutting the floor joists. 27--- • Cut the joists marked for removal 3 inches beyond the rough-opening marks, using a saber saw or a reciprocating saw, cutting as far as the sub-flooring above. Complete the cuts with a handsaw if necessary. • Pry the severed joists downward to free them. • Use carpenter’s flippers to clip ex posed nail points flush with the sub-flooring. In a house with I-beam joists, add filler between the flanges where the end of the header will fall, leaving a 9/16-inch gap between the filler and the bottom flange . Secure the header to the cut I-beams with I-beam joist hangers tall enough to reach the top flange, and fasten the header to the band joist with a framing connector. 5. Providing headers. • At each side of the opening, install a header made of doubled joist lumber to reach from the reinforced joist to the band joist. Nail the headers to the cut joists. • Attach headers to the reinforced joist with double joist hangers. Use single hangers to connect cut joists to headers and framing connectors to secure headers to the band joist. 6. Installing the bay joists. • Cut joists 6 inches longer than the distance from the reinforced house joist to the outside wall of the bay. • Nail joist hangers upside down to the reinforced joist, 16 inches apart. • Run a bead of construction adhesive along two-thirds of the top edge of the joists and slide them into place through the wall (above), then nail them in the joist hangers. • Secure the joists to the sill plate with metal framing anchors . If the house has I-beam joists, fill the space inside the flanges of the reinforced I-beam as in Step 5 and attach the new joists as above. COMPLETING THE PLATFORM 1. Cutting a pattern. 28--- • Set a strip of 0.5-inch exterior plywood on top of the window and mark the corners of the window casing on the plywood . • Using these reference points, cut out a plywood pattern in the shape of the bay. Employ this pattern to cut an identical piece of plywood. PLYWOOD; CASING 2. Fitting the bay header joists. 29--- • Set a piece of joist lumber along a side edge of the pattern and mark the length of the side on the board. • Tilt the blade of a circular saw to match the angle of the bay and cut the board at the marks. Make a similar piece fitted to the other side of the pattern. • Finally, cut a front header joist with square ends to fit between the two side pieces . 3. Trimming the joists. • Butt the pattern against the house subflooring and mark the outline of the pattern on the joists. • Set a 2-by-4 on edge atop the bay joists, its outside face flush with the pattern-outline marks. • Against the inside face of the 2-by-4, make a second set of marks on the joists , and trim the joists at these marks. • Nail the front header-joist section to the bay-joist ends, and toenail the side sections to the front section and to the band joist. • Nail the plywood pattern to the undersides of the bay joists. • Insulate between the joists. Use batts made with a vapor barrier attached, stapling the barrier material to the tops of the joists. • Run a bead of construction adhesive along the tops of the joists, and nail the subflooring that you cut in Step 1 to the joists. |
| HOME | Prev: ENLARGING THE GROUND FLOOR (index) | Next: Framing and Fitting the Window |
Monday, March 31, 2014 19:31 PST