4. ANÁLISIS DETALLADO DE LOS PROCESOS DE CAMBIO DE
4.5 DESGLOSE POR MOVILIDAD
178 BUILDING AN OUTDOOR ROOM
the natural contour of the land instead of a single-level deck that requires tall support posts. Houses built on a concrete slab can have a smaller slab poured to create a porch or patio area. Just make sure the slab is 1 in. or so below the floor slab to keep water from entering the house. To promote drainage, pour the slab with a slight slope, about 1⁄4 in. per ft. Don’t forget to thicken the concrete and install a metal post base where the posts will be installed to hold the sup- porting roof beams.
Some Habitat houses are built with ramps to accommodate people in wheelchairs or those who have limited mobility. Ramps can take up quite a bit of room. They need to be built with a gradual slope and must be at least 36 in. wide. The slope rate is usually a 1 in. vertical rise for every 1 ft. traveled horizontally. So if the door entrance is 16 in. above ground level, the ramp will need to be 16 ft. long.
Before you begin to build, you should also know which railing design you plan to use. Drive around a few neighborhoods and you’ll
A porch creates an outdoor living room. A small house can live large when a porch is part of the design. On this Habitat project, the porch shelters the main entry. [Photo courtesy HFHI]
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Size a deck to minimize waste. Take advantage of standard lumber lengths when determining the size of a deck. For example, a deck that’s 5 ft. 11 in. wide can be framed with 12-ft.-long joists or beams. A deck that’s 61⁄2 ft. widewould waste 11⁄2 ft. of an
8-ft. beam or joist.
Ramps with a slope of 1 in. per ft. can make a house accessible for people using a walker or wheelchair. [Photo by Don Charles Blom]
BUILDING AN OUTDOOR ROOM 179
certainly come upon some interesting railing designs to inspire your own efforts. Finally, consider your electrical wiring needs. Overhead light is important for security reasons, but you may also want to install some low-voltage lights on or around the porch or in nearby walkway or garden areas.
STEP 1 COMPLETE THE ESSENTIAL ROOF FRAMING
In many house designs, a section of the main roof extends over the porch. To complete the
installation of the roof trusses, roofing material, and exterior trim, the truss support beams over the porch must be cut and fastened to the wall framing. As shown in the illustration above, each beam rests in a pocket formed by a pair of jack studs framed in the house wall. The top of the beam is flush and level with the top of the wall plates.
In addition to nailing the beam to the wall framing, I strengthen the connection by nailing an 18-in. metal strap across the top of the beam and the double top plate of the wall. Beams made from rough 2× lumber can
7-A
Top plates
Metal strap ties porch beam to house structure.
Jack studs support porch beam
Porch beam sets into notch in wall.
Metal post cap
PT 4x4 post Metal
post base Concrete pier
Deck
Porch beams are level with the top of the top plate and are attached to the house frame with metal tie straps.
3/4 in. Set saw at 45° and cut 3/4 in. from end on all sides.
Result
The beam end can be cut to create a nice trim detail. Jack studs support beam. Notch cut in wall frame for porch beam
Post-and-beam support for a porch roof
Rim joist Metal
post base
POST-AND-BEAM SUPPORT FOR A PORCH ROOF
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Framing con- nectors are worth checking out. If you haven’t discovered the vast variety of fram- ing connectors that are available, try to do so before building a porch or a deck. A well-stocked lumberyard or building supplier will sell connect- ing hardware designed to reinforce all kinds of joints among different framing members.
180 BUILDING AN OUTDOOR ROOM
later be covered with aluminum cladding, as described in Chapter 6.
If it’s not possible to install permanent posts at this stage, temporary posts can be used to support porch ceiling beams. When you install perma- nent posts, be sure to secure them with framing connectors—a post base at the bottom and a post cap at the top that is fastened to the post and to the beams (see the photos above).
STEP 2 INSTALL THE LEDGER
On a house built over a basement or crawl space, a deck or porch can be attached to the house frame. Deck building then becomes a lot like framing a floor-joist system inside a house (see
Chapter 3). Step one in this process is to attach a ledger to the house frame. Straight, level, and solidly secured to the house, the ledger acts like a rim joist for the porch. It extends the full length of the porch, supporting its inboard side. There are several concerns when attaching a ledger, and all of them are important. First, the ledger must be at least 21⁄2 in. below the level of the interior floor. When 11⁄2-in. deck boards are screwed on top of the ledger, the deck will be 1 in. lower than the interior floor, which is just about right. If wheelchair accessibility is a concern, plan to build a small ramp to bridge the distance between the deck and the doorsill.
Reserve your best boards to use as ledgers— clear lumber with straight, square edges and
Framing connectors are essential. Steel connect- ing hardware is required when building a porch or a deck. A post base (see the photo at left) is mounted on a concrete pier; it has holes for lag bolts, which fasten it to the post. A post cap con- nector (see the photo above) is useful for strength- ening the joint between a porch post and a roof beam. [Photo at left © Memo Jasso/Brown Studio; photo above © Larry Haun]
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Larger decks may require more bolts to attach the ledger to the house frame. You have to think about the weight a deck might carry—a party with 50 people on a deck is a lot of weight.BUILDING AN OUTDOOR ROOM 181
no major imperfections (cracks, large knots, or warping). When installing a ledger, make sure water cannot get behind the ledger and into the house frame, where it could cause rot. And make sure the ledger is secured to the house in a man- ner that will hold for the life of the building.