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A stairway outdoors provides a private entrance for a second-story addition with no sacrifice of interior space below. Outside conditions require weather-resistant materials; use galvanized fasteners, which retard rust, and pressure-treated lumber, which is slow to rot or warp. The design below protects the stairs from ground moisture and termites with concrete piers and a concrete base. It also minimizes the risk of water damage to the house; the structure attaches to a wall only at the landing, where the joint can be waterproofed with flashing. The rest of the stairway is built an inch away from the wall, leaving the siding there intact. - Sizing the Stairway: Before buying wood, calculate the stairway dimensions. Start by marking the position of the landing beneath the second-story door. At the side of the door that will be farthest from the stairs, mark the house wall for one end of the landing at a point 4 inches outside the doorjamb and 5 inches below the threshold. Measuring toward the planned stairs, mark the wall for the other end of the landing 5.5 feet away. If the ground is roughly level, you can determine the stairs’ total vertical rise by measuring the height of the marks and subtracting 2 inches to allow for the concrete pad at the bottom of the stairs. Calculate total run, lay off the distance on the ground beginning beneath the landing mark farthest from the door, and mark the spot with a stake. For a sloping lot, calculate the run the same way, then adapt the design, shortening or lengthening the stairway as needed to accommodate the terrain. CAUTION---House siding might contain asbestos or lead. Consult our other discussion for advice on testing for and handling of these materials. SAFETY TIPS --- Protect your eyes with safety goggles as you hammer nails. When sawing pressure-treated lumber, add a dust mask, and wash your hands thoroughly afterward. Anatomy of an outdoor stair. 99--- Support for the treads of the stairway at right consists of three carriages secured to a landing at the top and a concrete base at the bottom. One side of the landing is attached to the house at the second-story floor framing; the other side rests on 4-by-4 posts set on concrete piers. Similar posts at the midpoint of the stair carriages keep the structure from shifting side to side. Balustrades are made of posts supporting handrails and guardrails that are fitted with vertical pickets. If the stairs don’t extend beyond the house, there is no room for posts between the inner carriage and the wall. Steady the carriage at its midpoint with a short post secured to the inside of the carriage face next to the wall. TOOLS:
MATERIALS:
99 A SCAFFOLD RAISED BY JACKS 1. Raising the uprights. 100a--- • Nail 10-foot 2-by-4s together to make two uprights. Drive nails into both sides of the up rights, 1 foot apart. • Bolt a brace near the top of each upright, with the bolt crossing the seam between the 2-by-4s. • Set the uprights 32 inches from the wall and 10 feet apart, flanking the doorway and with the longer arm of each brace running toward the other brace. On very soft ground, set the uprights on 2-by-12 wood sills. • Fasten the braces to the wall with nails driven through the siding and into the second story floor framing. 2. Operating the scaffold. 100b--- • Attach a jack to each up right with the two stationary rods and crank, then lay 2-by-10 planks across the jacks to create a platform. • With a helper, raise the scaffold by simultaneously pumping the foot levers on both jacks. • To lower the scaffold, work in unison with a helper. First, depress the foot levers. Then, while pushing down on the lower stationary rods, turn the cranks counterclockwise. • If you must raise or lower the scaffold by yourself, don’t move one end up or down more than a foot before bringing the other end to the same level. 100 BUILDING THE STAIRS 1. Assembling the landing frame. • Butt-nail four 2-by-8s together to make a frame 66 inches long and 36 inches wide. • Strengthen the inside corners with multipurpose framing connectors. • In a long side of the frame, bore three holes 1.5 inches below the top edge—one in the center and the others 6 inches from each end. Then, 3.5 inches below each hole, drill another. If your house has conventional framing or I-beam joists, drill 9/16-inch holes. For truss joists, drill 3/4-inch holes. • Within the frame, nail a 2-by-8 joist parallel to the long sides and centered between them. • Secure the joist with a joist hanger at each end. 2. Fastening the frame to the house. • Locate the marks made. Then mark the wall 1.5 inches—the flooring thickness—and 9 inches below each one to establish the position of the landing frame on the house. • Strip siding from just above to just below the frame position. Flash the upper edge. • If the second floor is made of I-beam or truss joists, consult the box below. Otherwise, have a helper hold the frame level against the house. Using the predrilled holes as guides, bore i-inch holes in the house; secure the platform with 4- by 3.5-inch lag screws and washers. = SAFE CONNECTIONS DIFFERENT FRAMING = 101c--- If you built the second-story floor with I-beam joists as described, at tach the platform as in Step 2. For an existing floor of I-beams or truss joists, inspect the framing for a lumber band joist. If none is present, cut away a 2-foot-wide section of ceiling next to the wall where the landing will be secured. To reinforce an I-beam, also strip exterior sheathing where the landing is to be attached Add wood filler on each side of the web, securing it with carriage bolts Replace the sheathing and attach the landing with 4- by 4 inch lag screws. To reinforce a truss, nail a 2-by 10 or 2-by-12, depending on truss height to the truss for the length of the landing, using 3-inch nails. Then attach the frame with 6-inch carriage bolts. TRUSS 101 3. Supporting the landing frame. 102a--- • While a helper holds the frame level, nail two 2-by-4s to the side of the frame as temporary underpinnings. • At the outside corners of the frame, hang plumb bobs from nails as shown the inset. • Fold the flashing over the platform frame and face-nail it in place. 4. Digging holes for the footings. 102b--- • Excavate for the piers beneath the plat form, using the plumb bobs as the centers. Extend the holes below the frost- line—the local building department can tell you the required depth. • Fit the mouth of each hole with a 12-inch-square form made of 2-by-4s held in place with stakes. • Set a 2-by-4 as a bridge between the forms and raise or lower the forms as needed to level the 2-by-4. • Prepare a similar hole and form, 4 feet square, for the stair base; position it so that the last step will rest fully on concrete and the greater portion of the base will lie in front of this step. If the frostline is very shallow, or if local code permits a floating slab in this situation, dig the hole only 4 inches deep. 102 5. Setting the anchors. 103a--- • Spread a 2-inch layer of gravel in each hole and fill the holes with concrete. • Set 8-inch anchor bolts in the center of the each pier before the concrete dries. • For a base more than a foot thick, install Y-shaped framing anchors for the carriage bottoms. (Such hardware is impractical in a thinner base.) Bend each anchor so that the wings are 1.5 inches apart, and push them into the concrete where the carriages will rest. Make sure the anchor nearest the house wall establishes a gap of about an inch between the wall and the inside carriage. • Allow 1 or 2 days for the concrete to set. Then take final measurements and cut the carriages. 6. Attaching the post anchors. 103b--- • At each pier, slide the base of a post anchor over the anchor bolt, add an offset washer, and screw a nut on loosely; you may need to ad just the base and washer to plumb the support post later. • Set the post support between the base’s flanges. 103 7. Installing the support posts. 104a--- • Measure and cut two 4-by-4 landing posts to fit snugly between the frame and the post anchors. • Before installing each post, attach an L-strap connector to it with joist- hanger nails, positioning the strap’s top edge 4 inches above the post and so the horizontal arm will point toward the center of the landing. • Set a post on a post support with the L strap against the landing frame. • With a helper, adjust the post anchor to bring the post plumb. Tighten the nut and nail the anchor flanges to the post. • Nail the L strap to the frame. • Toenail the frame to the post with 3.5 nails, drilling a 3/16-inch pilot hole for each nail. • Install the second post. • Remove the scaffold and the 2-by-4 temporary supports installed in Step 3. 8. Adding carriages and posts. 104b--- • Install the inner carriage. For a base with no Y anchors, place the carriage an inch from the wall and attach the top to the platform with a multipurpose framing connector. Otherwise, put the foot of the carriage in a Y anchor and nail the anchor wings to the carriage before securing it to the platform. • Attach the other carriages and install spacers between them. • Cut five 4-by-4 posts long enough to reach from the bottom of the landing frame to the desired handrail height. • Using two carriage bolts, washers, and nuts each, attach the posts to the landing frame as follows: Place one post an inch from the house at the corner of the frame next to the doorway. Moving along the frame away from the house to the next corner, attach two posts. Inset each 4 inches from the corner. The fourth post goes halfway along the frame. Bolt the fifth to the frame where it meets the outer carriage, placing the bolts on a diagonal to avoid the corner of the L strap. • With carriage bolts, attach 45-inch 4-by-4 posts to the outer carriage and the exposed part of the inner carriage at intervals no more than 5 feet apart, skipping one position on each to leave room for midspan posts. 104 9. Installing midspan supports. 105a--- • Drop a plumb line from the post positions reserved in Step 8. • Dig an 8-inch square hole centered on each plumb-bob position and deeper than the frostline. Prepare concrete piers as in Steps 5 and 6. • At each pier, set a 4-by-4 post in place, plumb it, then bolt the post to the carriage and nail it to the post anchor. • Mark outer carriage posts for cutting with a chalk line stretched from the top of the landing corner post nearest the stairs and parallel to the carriages. Trim the posts at the marks, then bevel the inner posts to match. • For each tread, cut two 2-by-6s 38 inches long, notching the ends to fit around posts and trimming 1 inch from the ends beside the house wall. Nail treads to the carriages with a ¼-inch space between them, providing a 1/2-inch overhang beside the wall and a 1.5-inch overhang elsewhere. • Cut 2-by-6s to the same length for use as platform flooring boards. Nail them to the frame, using the same notching and spacing as for the treads. 10. Putting on the rails. 105b--- • Nail three 2-by-4 guardrails to the in sides of the posts on the stairs and the plat form, placing the upper rail even with the post tops; the distance between the bottom rail and the floor or treads is regulated by local codes. Make a miter cut where the stair rails meet the platform rails. • Cut 2-by-6 handrails for the platform and stair railings; miter the ends for the joints at the head of the stair and at the outer corner of the platform. Nail the handrails to the edge of the upper guardrail. Place the handrail joints between posts; for weatherproofing, the end grain of each post must be completely covered. • Cut 2-by-2 pickets to fit between the top and bottom guardrails, mitering both ends of the pickets intended for the carriage rails. Attach the pickets to the guardrails with No. 10 galvanized screws, placing the pickets no more than 4 inches apart. |
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Monday, December 26, 2016 8:52 PST