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Framing, in construction, is the fitting together of pieces to give a structure support and shape. [ citation needed ]Framing materials are usually wood, engineered wood, or structural steel. The alternative to framed construction is generally called mass wall construction, where horizontal layers of stacked materials such as log building, masonry, rammed earth, adobe, etc. are used without framing.
Building framing is divided into two broad categories,heavy-frame construction (heavy framing) if the vertical supports are few and heavy such as in timber framing, pole building framing, or steel framing; or light-frame construction (light-framing) if the supports are more numerous and smaller, such as balloon, platform, or light-steel framing. Light-frame construction using standardized dimensional lumber has become the dominant construction method in North America and Australia due to the economy of the method; use of minimal structural material allows builders to enclose a large area at minimal cost while achieving a wide variety of architectural styles.
Modern light-frame structures usually gain strength from rigid panels (plywood and other plywood-like composites such as oriented strand board (OSB) used to form all or part of wall sections), but until recently carpenters employed various forms of diagonal bracing to stabilize walls. Diagonal bracing remains a vital interior part of many roof systems, and in-wall wind braces are required by building codes in many municipalities or by individual state laws in the United States. Special framed shear walls are becoming more common to help buildings meet the requirements of earthquake engineering and wind engineering.
Historically, people fitted naturally shaped wooden poles together as framework and then began using joints to connect the timbers, a method today called traditional timber framing' or log framing. In the United States, timber framing was superseded by balloon framing beginning in the 1830s. Balloon framing makes use of many lightweight wall members called studs rather than fewer, heavier supports called posts; balloon framing components are nailed together rather than fitted using joinery. The studs in a balloon frame extend two stories from sill to plate. Platform framing superseded balloon framing and is the standard wooden framing method today. The name comes from each floor level being framed as a separate unit or platform.
Framed construction was rarely used in Scandinavia before the 20th century because of the abundant availability of wood, an abundance of cheap labour, and the superiority of the thermal insulation of logs; hence timber framing did not take off there first for unheated buildings such as farm buildings, outbuildings and summer villas, and for houses until the development of wall insulation.
Wall framing in house construction includes the vertical and horizontal members of exterior walls and interior partitions, both of bearing walls and non-bearing walls. These stick members, referred to as studs, wall plates and lintels (sometimes called headers), serve as a nailing base for all covering material and support the upper floor platforms, which provide the lateral strength along a wall. The platforms may be the boxed structure of a ceiling and roof, or the ceiling and floor joists of the story above.In the building trades, the technique is variously referred to as stick and frame, stick and platform, or stick and box, as the sticks (studs) give the structure its vertical support, and the box-shaped floor sections with joists contained within length-long post and lintels (more commonly called headers), support the weight of whatever is above, including the next wall up and the roof above the top story. The platform also provides lateral support against wind and holds the stick walls true and square. Any lower platform supports the weight of the platforms and walls above the level of its component headers and joists.
Framing lumber is subject to regulated standards that require a grade-stamp, and a moisture content not exceeding 19%.
There are three historically common methods of framing a house.
Wall sheathing, usually a plywood or other laminate, is usually applied to the framing prior to erection, thus eliminating the need to scaffold, and again increasing speed and cutting manpower needs and expenses. Some types of exterior sheathing, such as asphalt-impregnated fiberboard, plywood, oriented strand board and waferboard, will provide adequate bracing to resist lateral loads and keep the wall square. (Construction codes in most jurisdictions require a stiff plywood sheathing.) Others, such as rigid glass-fiber, asphalt-coated fiberboard, polystyrene or polyurethane board, will not.In this latter case, the wall should be reinforced with a diagonal wood or metal bracing inset into the studs. In jurisdictions subject to strong wind storms (hurricane countries, tornado alleys) local codes or state law will generally require both the diagonal wind braces and the stiff exterior sheathing regardless of the type and kind of outer weather resistant coverings.
A multiple-stud post made up of at least three studs, or the equivalent, is generally used at exterior corners and intersections to secure a good tie between adjoining walls, and to provide nailing support for interior finishes and exterior sheathing. Corners and intersections, however, must be framed with at least two studs.
Nailing support for the edges of the ceiling is required at the junction of the wall and ceiling where partitions run parallel to the ceiling joists. This material is commonly referred to as dead wood or backing.
Wall framing in house construction includes the vertical and horizontal members of exterior walls and interior partitions. These members, referred to as studs, wall plates and lintels, serve as a nailing base for all covering material and support the upper floors, ceiling and roof.
Exterior wall studs are the vertical members to which the wall sheathing and cladding are attached. 1.5 by 3.5 inches (38 mm × 89 mm) or 1.5 in × 5.5 in (38 mm × 140 mm) lumber and are commonly spaced at 16 in (410 mm) on center. This spacing may be changed to 12 or 24 in (300 or 610 mm) on center depending on the load and the limitations imposed by the type and thickness of the wall covering used. Wider 1.5 in × 5.5 in (38 mm × 140 mm) studs may be used to provide space for more insulation. Insulation beyond that which can be accommodated within a 3.5 in (89 mm) stud space can also be provided by other means, such as rigid or semi-rigid insulation or batts between 1.5 in × 1.5 in (38 mm × 38 mm) horizontal furring strips, or rigid or semi-rigid insulation sheathing to the outside of the studs. The studs are attached to horizontal top and bottom wall plates of 1.5 in (38 mm) lumber that are the same width as the studs.They are supported on a bottom plate or foundation sill and in turn support the top plate. Studs usually consist of
Interior partitions supporting floor, ceiling or roof loads are called loadbearing walls; others are called non-loadbearing or simply partitions. Interior loadbearing walls are framed in the same way as exterior walls. Studs are usually 1.5 in × 3.5 in (38 mm × 89 mm) lumber spaced at 16 in (410 mm) on center. This spacing may be changed to 12 or 24 in (300 or 610 mm) depending on the loads supported and the type and thickness of the wall finish used.
Partitions can be built with 1.5 in × 2.5 in (38 mm × 64 mm) or 1.5 in × 3.5 in (38 mm × 89 mm) studs spaced at 16 or 24 in (410 or 610 mm) on center depending on the type and thickness of the wall finish used. Where a partition does not contain a swinging door, 1.5 in × 3.5 in (38 mm × 89 mm) studs at 16 in (410 mm) on center are sometimes used with the wide face of the stud parallel to the wall. This is usually done only for partitions enclosing clothes closets or cupboards to save space. Since there is no vertical load to be supported by partitions, single studs may be used at door openings. The top of the opening may be bridged with a single piece of 1.5 in (38 mm) lumber the same width as the studs. These members provide a nailing support for wall finish, door frames and trim.
Lintels (or, headers) are the horizontal members placed over window, door and other openings to carry loads to the adjoining studs. in (nominal) (38 mm) lumber separated with spacers to the width of the studs and nailed together to form a single unit. Lintels are predominately nailed together without spacers to form a solid beam and allow the remaining cavity to be filled with insulation from the inside. The preferable spacer material is rigid insulation. The depth of a lintel is determined by the width of the opening and vertical loads supported.Lintels are usually constructed of two pieces of 2
The complete wall sections are then raised and put in place, temporary braces added and the bottom plates nailed through the subfloor to the floor framing members. The braces should have their larger dimension on the vertical and should permit adjustment of the vertical position of the wall.
Once the assembled sections are plumbed, they are nailed together at the corners and intersections. A strip of polyethylene is often placed between the interior walls and the exterior wall, and above the first top plate of interior walls before the second top plate is applied to attain continuity of the air barrier when polyethylene is serving this function.
A second top plate, with joints offset at least one stud space away from the joints in the plate beneath, is then added. This second top plate usually laps the first plate at the corners and partition intersections and, when nailed in place, provides an additional tie to the framed walls. Where the second top plate does not lap the plate immediately underneath at corner and partition intersections, these may be tied with 0.036 in (0.91 mm) galvanized steel plates at least 3 in (76 mm) wide and 6 in (150 mm) long, nailed with at least three 2.5 in (64 mm) nails to each wall.
Balloon framing is a method of wood construction – also known as "Chicago construction" in the 19th century – used primarily in areas rich in softwood forests: Scandinavia, Canada, the United States up until the mid-1950s, and around Thetford Forest in Norfolk, England. The name comes from a French Missouri type of construction, maison en boulin , boulin being a French term for a horizontal scaffolding support.
Balloon framing uses long continuous framing members (studs) that run from the sill plate to the top plate, with intermediate floor structures let into and nailed to them.Here the heights of window sills, headers and next floor height would be marked out on the studs with a story pole. Once popular when long lumber was plentiful, balloon framing has been largely replaced by platform framing.
It is not certain who introduced balloon framing in the United States. However, the first building using balloon framing was possibly a warehouse constructed in 1832 in Chicago, Illinois, by George Washington Snow.Architectural critic Sigfried Giedion cited Chicago architect John M. Van Osdel's 1880s attribution, as well as A. T. Andreas' 1885 History of Chicago, to credit Snow as 'inventor of the balloon frame method'. In 1833, Augustine Taylor (1796–1891) constructed St. Mary's Catholic Church in Chicago using the balloon framing method.
In the 1830s, Hoosier Solon Robinson published articles about a revolutionary new framing system, called "balloon framing" by later builders. Robinson's system called for standard 2x4 lumber, nailed together to form a sturdy, light skeleton. Builders were reluctant to adopt the new technology, however, by the 1880s, some form of 2x4 framing was standard.
Alternatively, a precursor to the balloon frame may have been used by the French in Missouri as much as thirty-one years earlier.
Although lumber was plentiful in 19th-century America, skilled labor was not. The advent of cheap machine-made nails, along with water-powered sawmills in the early 19th century made balloon framing highly attractive, because it did not require highly skilled carpenters, as did the dovetail joints, mortises and tenons required by post-and-beam construction. For the first time, any farmer could build his own buildings without a time-consuming learning curve.
It has been said that balloon framing populated the western United States and the western provinces of Canada. Without it, western boomtowns certainly could not have blossomed overnight. [ citation needed ] For example, many 19th-century New England working neighborhoods consist of balloon-constructed three-story apartment buildings referred to as triple deckers. However, balloon framing did require very long studs and as tall trees were exhausted in the 1920s, platform framing became prevalent.It is also likely that, by radically reducing construction costs, balloon framing improved the shelter options of poorer North Americans.
The main difference between platform and balloon framing is at the floor lines. The balloon wall studs extend from the sill of the first story all the way to the top plate or end rafter of the second story. The platform-framed wall, on the other hand, is independent for each floor.
Light-frame materials are most often wood or rectangular steel, tubes or C-channels. Wood pieces are typically connected with nail fasteners, nails, or screws; steel pieces are connected with pan-head framing screws, or nuts and bolts. Preferred species for linear structural members are softwoods such as spruce, pine and fir. Light frame material dimensions range from 38 by 89 mm (1.5 by 3.5 in); i.e., a Dimensional number two-by-four to 5 cm by 30 cm (two-by-twelve inches) at the cross-section, and lengths ranging from 2.5 metres (8.2 ft) for walls to 7 metres (23 ft) or more for joists and rafters. Recently, architects have begun experimenting with pre-cut modular aluminum framing to reduce on-site construction costs.
Wall panels built of studs are interrupted by sections that provide rough openings for doors and windows. Openings are typically spanned by a header or lintel that bears the weight of the structure above the opening. Headers are usually built to rest on trimmers, also called jacks. Areas around windows are defined by a sill beneath the window, and cripples, which are shorter studs that span the area from the bottom plate to the sill and sometimes from the top of the window to a header, or from a header to a top plate. Diagonal bracings made of wood or steel provide shear (horizontal strength) as do panels of sheeting nailed to studs, sills and headers. [ citation needed ]
Wall sections usually include a bottom plate which is secured to the structure of a floor, and one, or more often two top plates that tie walls together and provide a bearing for structures above the wall. Wood or steel floor frames usually include a rim joist around the perimeter of a system of floor joists, and often include bridging material near the center of a span to prevent lateral buckling of the spanning members. In two-story construction, openings are left in the floor system for a stairwell, in which stair risers and treads are most often attached to squared faces cut into sloping stair stringers.[ citation needed ]
Interior wall coverings in light-frame construction typically include wallboard, lath and plaster or decorative wood paneling.[ citation needed ]
Exterior finishes for walls and ceilings often include plywood or composite sheathing, brick or stone veneers, and various stucco finishes. Cavities between studs, usually placed 40–60 cm (16–24 in) apart, are usually filled with insulation materials, such as fiberglass batting, or cellulose filling sometimes made of recycled newsprint treated with boron additives for fire prevention and vermin control. [ citation needed ]
In natural building, straw bales, cob and adobe may be used for both exterior and interior walls.
The part of a structural building that goes diagonally across a wall is called a T-bar. It stops the walls from collapsing in gusty winds. [ citation needed ]
Roofs are usually built to provide a sloping surface intended to shed rain or snow, with slopes ranging from 1:15 (less than an inch per linear foot of horizontal span), to steep slopes of more than 2:1. A light-frame structure built mostly inside sloping walls which also serve as a roof is called an A-frame.
Roofs are most oftencovered with shingles made of asphalt, fiberglass and small gravel coating, but a wide range of materials are used. Molten tar is often used to waterproof flatter roofs, but newer materials include rubber and synthetic materials. Steel panels are popular roof coverings in some areas, preferred for their durability. Slate or tile roofs offer more historic coverings for light-frame roofs.
Light-frame methods allow easy construction of unique roof designs; hip roofs, for example, slope toward walls on all sides and are joined at hip rafters that span from corners to a ridge. Valleys are formed when two sloping roof sections drain toward each other. Dormers are small areas in which vertical walls interrupt a roof line, and which are topped off by slopes at usually right angles to a main roof section. Gables are formed when a length-wise section of sloping roof ends to form a triangular wall section. Clerestories are formed by an interruption along the slope of a roof where a short vertical wall connects it to another roof section. Flat roofs, which usually include at least a nominal slope to shed water, are often surrounded by parapet walls with openings (called scuppers) to allow water to drain out. Sloping crickets are built into roofs to direct water away from areas of poor drainage, such as behind a chimney at the bottom of a sloping section.
Light-frame buildings in areas with shallow or nonexistent frost depths are often erected on monolithic concrete-slab foundations that serve both as a floor and as a support for the structure. Other light-frame buildings are built over a crawlspace or a basement, with wood or steel joists used to span between foundation walls, usually constructed of poured concrete or concrete blocks.
Engineered components are commonly used to form floor, ceiling and roof structures in place of solid wood. I-joists (closed-web trusses) are often made from laminated woods, most often chipped poplar wood, in panels as thin as 1 cm (0.39 in), glued between horizontally laminated members of less than 4 cm by 4 cm (two-by-twos), to span distances of as much as 9 m (30 ft). Open web trussed joists and rafters are often formed of 4 cm by 9 cm (two-by-four) wood members to provide support for floors, roofing systems and ceiling finishes.
Platform framing was traditionally limited to four floors but some jurisdictions have modified their building codes to allow up to six floors with added fire protection.
A roof is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temperature, and wind. A roof is part of the building envelope.
A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including:
Lumber, also known as timber, is a type of wood that has been processed into beams and planks, a stage in the process of wood production. Lumber is mainly used for structural purposes but has many other uses as well.
A floor is the bottom surface of a room or vehicle. Floors vary from simple dirt in a cave to many-layered surfaces made with modern technology. Floors may be stone, wood, bamboo, metal or any other material that can support the expected load.
A structural insulated panel, or structural insulating panel, (SIP), is a form of sandwich panel used in the construction industry.
A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members. When incorporated into a floor framing system, joists serve to provide stiffness to the subfloor sheathing, allowing it to function as a horizontal diaphragm. Joists are often doubled or tripled, placed side by side, where conditions warrant, such as where wall partitions require support.
Lath and plaster is a building process used to finish mainly interior dividing walls and ceilings. It consists of narrow strips of wood (laths) which are nailed horizontally across the wall studs or ceiling joists and then coated in plaster. The technique derives from an earlier, more primitive, process called wattle and daub.
Sound Transmission Class is an integer rating of how well a building partition attenuates airborne sound. In the US, it is widely used to rate interior partitions, ceilings, floors, doors, windows and exterior wall configurations. Outside the US, the Sound Reduction Index (SRI) ISO index is used. The STC rating very roughly reflects the decibel reduction of noise that a partition can provide. The STC is useful for evaluating annoyance due to speech sounds, but not music or machinery noise as these sources contain more low frequency energy than speech.
A tie, strap, tie rod, eyebar, guy-wire, suspension cables, or wire ropes, are examples of linear structural components designed to resist tension. It is the opposite of a strut or column, which is designed to resist compression. Ties may be made of any tension resisting material.
Steel frame is a building technique with a "skeleton frame" of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The development of this technique made the construction of the skyscraper possible.
A plate or wall plate is a horizontal, structural, load-bearing member in wooden building framing.
Domestic roof construction is the framing and roof covering which is found on most detached houses in cold and temperate climates. Such roofs are built with mostly timber, take a number of different shapes, and are covered with a variety of materials.
A wall stud is a vertical framing member in a building's wall of smaller cross section than a post. They are a fundamental element in frame building.
A steel building is a metal structure fabricated with steel for the internal support and for exterior cladding, as opposed to steel framed buildings which generally use other materials for floors, walls, and external envelope. Steel buildings are used for a variety of purposes including storage, work spaces and living accommodation. They are classified into specific types depending on how they are used.
Building insulation materials are the building materials which form the thermal envelope of a building or otherwise reduce heat transfer.
In the framing of a deck or floor system, a rim joist is attached perpendicular to the joists, and provides lateral support for the ends of the joists while capping off the end of the floor or deck system. Rim joists are not to be confused with end joists, which are the first and last joists at the ends of a row of joists that make up a floor or deck frame.
The Mitchell – Foster – Young House is a historic house located just outside Oxford, Mississippi off the highway to New Albany. The house, thought to be one of the oldest standing farmhouses in the county, is listed on the National Register of Historic Places.
Cold-formed steel (CFS) is the common term for steel products shaped by cold-working processes carried out near room temperature, such as rolling, pressing, stamping, bending, etc. Stock bars and sheets of cold-rolled steel (CRS) are commonly used in all areas of manufacturing. The terms are opposed to hot-formed steel and hot-rolled steel.
A post is a main vertical or leaning support in a structure similar to a column or pillar but the term post generally refers to a timber but may be metal or stone. A stud in wooden or metal building construction is similar but lighter duty than a post and a strut may be similar to a stud or act as a brace. In the U.K. a strut may be very similar to a post but not carry a beam. In wood construction posts normally land on a sill, but in rare types of buildings the post may continue through to the foundation called an interrupted sill or into the ground called earthfast, post in ground, or posthole construction. A post is also a fundamental element in a fence. The terms "jack" and "cripple" are used with shortened studs and rafters but not posts, except in the specialized vocabulary of shoring.
American historic carpentry is the historic methods with which wooden buildings were built in what is now the United States since European settlement. A number of methods were used to form the wooden walls and the types of structural carpentry are often defined by the wall, floor, and roof construction such as log, timber framed, balloon framed, or stacked plank. Some types of historic houses are called plank houses but plank house has several meanings which are discussed below. Roofs were almost always framed with wood, sometimes with timber roof trusses. Stone and brick buildings also have some wood framing for floors, interior walls and roofs.
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