Rungrado May Day Stadium

Rungrado May Day Stadium has 150 000 seats and a total floor space of more than 207 000 square metres. The area of the pitches is over 22 500 square metres. The stadium has eight storeys and is more than 60 metres high from the ground to the roof. The 60 metre long canopy is enough to cover the section of the stands. The pent of the inner roof is 60 metres long and the outer roof 40m long. The 16 arch roofs link with one another like flower petals.

The roofs look like a large flower floating on the clear water of the Taedong, or a parachute which has just landed, so it gives the impression of a dynamic sculpture. The stadium has 80 exits and ten lifts. It was built in two and a half years on the picturesque Rungra Island in the Taedong River, and commissioned on May 1, 1989. Every condition is provided for international games. The football pitch is covered with natural grass, and the 400 metre track and other parts for field events are rubberised.

The stadium has various training halls, recreation rooms, an indoor swimming pool, an ultrasonic bat, a sauna, beds and so on, which are indispensable for the players training and convenience. It also has dining rooms, and a broadcasting room and telex booths. The rubberised indoor running track is several hundred metres long and is on the sixth floor.

Source: www.worldstadiums.com

Heavy equipment operator

An excavator. The bucket is raked toward the machine to create a trench or pit while the lower jaw enables logs to be moved and loaded and buildings to be dismantled. The lower jaw on this excavator makes it a particularly specialised machine. Most excavators have only the bucket fitted

A wheeled front loader at work. This wheeled tractor is equipped with a large bucket, which can be raised or lowered by hydraulic arms.

A heavy equipment operator drives and operates engineering vehicles used in engineering and construction projects.

Operator training

The International Union of Operating Engineers has equipment schools where apprentice operators are trained.

The Association of Equipment Manufacturers provides effective safety training materials for operators of rough terrain forklifts and operators of industrial and agricultural mowers.

The National Association of Heavy Equipment Training Schools provides American national certification for heavy equipment operator

Interior Heavy Equipment School (www.iheschool.com) provides Canadian certification for heavy equipment operators

Currently there is not an international association of heavy equipment schools.

Source : http://en.wikipedia.org

Glazing in construction (Architectural glass)

Architectural glass is glass that is used as a building material. It is most typically used as transparent glazing material in the building envelope, including windows in the external walls. Glass is also used for internal partitions and as an architectural feature. When used in buildings, glass is often of a safety type, which include reinforced, toughened and laminated glasses.

A building in Canterbury, England, which displays its long history in different building styles and glazing of every century from the 16th to the 20th included.

Crown glass: The earliest style of glass window

the concentric arcs that distort some of these panes indicate they are crown glass, possibly of the 16th century.

The earliest method of glass window manufacture was the crown glass method. Hot blown glass was cut open opposite the pipe, then rapidly spun on a table before it could cool. Centrifugal force forced the hot globe of glass into a round, flat sheet. The sheet would then be broken off the pipe and trimmed to form a rectangular window to fit into a frame.

At the center of a piece of crown glass, a thick remnant of the original blown bottle neck would remain, hence the name "bullseye." Optical distortions produced by the bullseye could be reduced by grinding the glass. The development of diaper latticed windows was in part because three regular diamond-shaped panes could be conveniently cut from a piece of Crown glass, with minimum waste and with minimum distortion.

This method for manufacturing flat glass panels was very expensive and could not be used to make large panes. It was replaced in the 19th century by the cylinder, sheet and rolled plate processes, but it is still used in traditional construction and restoration.

Cylinder glass

Main articles: Cylinder blown sheet and Machine drawn cylinder sheet. In this manufacturing process glass is blown into a cylindrical iron mould. The ends are cut off and a cut is made down the side of the cylinder. The cut cylinder is then placed in an oven where the cylinder unrolls into a flat glass sheet.

Sheet glass

The uneven surface of old glass is visible in the reflection on this window pane.

Sheet glass (sometimes called window glass or drawn glass) was made by dipping a leader into a vat of molten glass then pulling that leader straight up while a film of glass hardened just out of the vat. This film or ribbon was pulled up continuously held by tractors on both edges while it cooled. After 12 meters or so it was cut off the vertical ribbon and tipped down to be further cut. This glass is clear but has thickness variations due to small temperature changes just out of the vat as it was hardening. These variations cause lines of slight distortions. You may still see this glass in older houses. Float glass replaced this process.

Rolled plate glass

The glass is taken from the furnace in large iron ladles, which are carried upon slings running on overhead rails; from the ladle the glass is thrown upon the cast-iron bed of a rolling-table; and is rolled into sheet by an iron roller, the process being similar to that employed in making plate-glass, but on a smaller scale. The sheet thus rolled is roughly trimmed while hot and soft, so as to remove those portions of glass which have been spoiled by immediate contact with the ladle, and the sheet, still soft, is pushed into the open mouth of an annealing tunnel or temperature-controlled oven called a lehr, down which it is carried by a system of rollers.

Polished plate glass

The plate glass process starts with sheet or rolled plate glass. This glass is dimensionally inaccurate and often created visual distortions. These rough panes were ground flat and then polished clear. This was a fairly expensive process.

Before the float process, mirrors were plate glass as sheet glass had visual distortions that were akin to those seen in amusement park or fun-fair mirrors.

Figure rolled glass

Figure rolled glass

The elaborate patterns found on figure rolled glass are produced in a similar fashion to the rolled plate glass process except that the plate is cast between two rollers, one of which carries a pattern. The pattern is impressed upon the sheet by a printing roller which is brought down upon the glass as it leaves the main rolls while still soft. This glass shows a pattern in high relief. The glass is then annealed in a lehr.

The glass used for this purpose is typically whiter in colour than the clear glasses used for other applications.

This glass can be laminated or toughened depending on the depth of the pattern to produce a safety glass.

Float glass

90% of the world's flat glass is produced by the float glass process invented in the 1950s by Sir Alastair Pilkington of Pilkington Glass, in which molten glass is poured onto one end of a molten tin bath. The glass floats on the tin, and levels out as it spreads along the bath, giving a smooth face to both sides. The glass cools and slowly solidifies as it travels over the molten tin and leaves the tin bath in a continuous ribbon. The glass is then annealed by cooling in an oven called a lehr. The finished product has near-perfect parallel surfaces.

A very small amount of the tin is embedded into the glass on the side it touched. The tin side is easier to make into a mirror. This "feature" quickened the switch from plate to float glass. The tin side of glass is also softer and easier to scratch.

Glass is produced in standard metric thicknesses of 2, 3, 4, 5, 6, 8, 10, 12, 15, 19 and 22 mm. Molten glass floating on tin in a nitrogen/hydrogen atmosphere will spread out to a thickness of about 6 mm and stop due to surface tension. Thinner glass is made by stretching the glass while it floats on the tin and cools. Similarly, thicker glass is pushed back and not permitted to expand as it cools on the tin.

Prism Glass

Prism glass is architectural glass used around the turn of the century to provide lighting to underground spaces and areas that would otherwise be to difficult to light. Prism glass uses a unique convex lens design to help illuminate more than ordinary glass. Prism glass can sometimes be found on sidewalks and in this form is known as vault lighting.

Glass block

Glass brick, also known as glass block, is an architectural element made from glass used in areas where privacy or visual obscuration is desired while admitting light, such as underground parking garages, washrooms, and municipal swimming baths. Glass block was originally developed in the early 1900s to provide natural light in industrial factories.

Annealed glass

Annealed glass is glass without internal stresses caused by heat treatment, i.e., rapid cooling, or by toughening or heat strengthening. Glass becomes annealed if it is heated above a transition point then allowed to cool slowly, without being quenched. Float glass is annealed during the process of manufacture. However, most toughened glass is made from float glass that has been specially heat-treated.

Annealed glass breaks into large, jagged shards that can cause serious injury, and thus, the reason it is considered a hazard in architectural applications. Building codes in many parts of the world restrict the use of annealed glass in areas where there is a high risk of breakage and injury, for example in bathrooms, in door panels, fire exits and at low heights in schools or domestic houses.

Laminated glass

Broken laminated glass

Laminated glass is a type of safety glass that holds together when shattered. In the event of breakage, it is held in place by an interlayer, typically of PVB, between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a characteristic "spider web" cracking pattern when the impact is not enough to completely pierce the glass.

Laminated glass is normally used when there is a possibility of human impact or where the glass could fall if shattered. Shopfront glazing and windshields are typically laminated glasses. The PVB interlayer also gives the glass a much higher sound insulation rating, due to the damping effect, and also blocks 99% of transmitted UV light.

Toughened glass (tempered glass)

Toughened glass in a vandalized phone booth in Britain

Toughened glass (also known as tempered glass) is a type of safety glass that has increased strength and will usually shatter in small, square pieces when broken. It is used when strength, thermal resistance and safety are important considerations. Using toughened glass on automobile windshields would be a problem when a small stone hits the windshield at speed, as it would shatter into small squares endangering the driver and passengers. In commercial structures it is used in unframed assemblies such as frameless doors, structurally loaded applications and door lites and vision lites adjacent to doors. Toughened glass is typically four to six times the strength of annealed glass.

Heat-strengthened glass

Heat-strengthened glass is glass that has been heat treated to induce surface compression, but not to the extent of causing it to "dice" on breaking in the manner of tempered glass. On breaking, heat-strengthened glass breaks into sharp pieces that are typically somewhat smaller than those found on breaking annealed glass, and is intermediate in strength between annealed and toughened glasses.

Chemically strengthened glass

Chemically strengthened glass is a type of glass that has increased strength. When broken it still shatters in long pointed splinters similar to float (annealed) glass. For this reason, it is not considered a safety glass and must be laminated if a safety glass is required. Chemically strengthened glass is typically six to eight times the strength of annealed glass.

The glass is chemically strengthened by submerging the glass in a bath containing a potassium salt (typically potassium nitrate) at 450 °C. This causes sodium ions in the glass surface to be replaced by potassium ions from the bath solution.

Unlike toughened glass, chemically strengthened glass may be cut after strengthening, but loses its added strength within the region of approximately 20 mm of the cut. Similarly, when the surface of chemically strengthened glass is deeply scratched, this area loses its additional strength.

Chemically strengthened glass was used on some fighter aircraft canopies.

Self-cleaning glass

A recent innovation is so-called self-cleaning glass, aimed at building, automotive and other technical applications. A nanometre-scale coating of titanium dioxide on the outer surface of glass introduces two mechanisms which lead to the self-cleaning property. The first is a photo-catalytic effect, in which ultra-violet rays catalyse the breakdown of organic compounds on the window surface; the second is a hydrophilic effect in which water is attracted to the surface of the glass, forming a thin sheet which washes away the broken-down organic compounds.

Insulated glazing

Insulated glazing, or double glazing is a piece of glazing consisting of two or more layers of glazing separated by a spacer along the edge and sealed to create a dead air space between the layers. This type of glazing has functions of thermal insulation and noise reduction.

Evacuated glazing

Another recent innovation for insulated glazing is evacuated glass, which as yet is produced commercially only in Japan and China. The extreme thinness of evacuated glazing offers many new architectural possibilities, particularly in building conservation and historicist architecture, where evacuated glazing can replace traditional (much less energy-efficient) single glazing.

An evacuated glazing unit is made by sealing the edges of two glass sheets, typically by using a solder glass, and evacuating the space inside with a vacuum pump. The evacuated space between the two sheets can be very shallow and yet be a good insulator, yielding insulative window glass with nominal thicknesses as low as 6 mm overall. The reasons for this low thickness are deceptively complex, but the potential insulation is good essentially because there can be no convection or gaseous conduction in a vacuum.

Unfortunately, evacuated glazing does have some disadvantages; its manufacture is complicated and difficult. For example, a necessary stage in the manufacture of evacuated glazing is outgassing; that is, heating it to liberate any gases adsorbed on the inner surfaces, which could otherwise later escape and destroy the vacuum. This heating process currently means that evacuated glazing cannot be toughened or heat-strengthened. If an evacuated safety glass is required, the glass must be laminated. The high temperatures necessary for outgassing also tend to destroy the highly effective "soft" low-emissivity coatings that are often applied to one or both of the internal surfaces (i.e. the ones facing the air gap) of other forms of modern insulative glazing, in order to prevent loss of heat through infrared radiation. Slightly less effective "hard" coatings are still suitable for evacuated glazing, however.

Furthermore, because of the atmospheric pressure present on the outside of an evacuated glazing unit, its two glass sheets must somehow be held apart in order to prevent them flexing together and touching each other, which would defeat the object of evacuating the unit. The task of holding the panes apart is performed by a grid of spacers, which typically consist of small stainless steel discs that are placed around 20 mm apart. The spacers are small enough that they are visible only at very close distances, typically up to 1 m. However, the fact that the spacers will conduct some heat often leads in cold weather to the formation of temporary, grid-shaped patterns on the surface of an evacuated window, consisting either of small circles of interior condensation centred around the spacers, where the glass is slightly colder than average, or, when there is dew outside, small circles on the exterior face of the glass, in which the dew is absent because the spacers make the glass near them slightly warmer.

The conduction of heat between the panes, caused by the spacers, tends to limit evacuated glazing’s overall insulative effectiveness. Nevertheless, evacuated glazing is still as insulative as much thicker conventional double glazing and tends to be stronger, since the two constituent glass sheets are pressed together by the atmosphere, and hence react practically as one thick sheet to bending forces. Evacuated glazing also offers very good sound insulation in comparison with other popular types of window glazing.

Source : http://en.wikipedia.org

Framing (construction)

A two-story wooden-frame house under construction—the location of the upper floor platform is readily discerned by the wide joists between the floors, and the upper structure rests on this platform.

For other uses, see Framing (disambiguation).

Framing, in construction known as light frame construction, is a building technique based around structural members, usually called studs, which provide a stable frame to which interior and exterior wall coverings are attached, and covered by a roof comprising horizontal ceiling joists and sloping rafters (together forming a truss structure) or manufactured pre-fabricated roof trusses—all of which are covered by various sheathing materials to give weather resistance.

Modern light-frame structures usually gain strength from rigid panels (plywood and other plywood like composites such as OSB) used to form all or part of wall sections, but until recently carpenters employed various forms of diagonal bracing (called "wind braces") 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.

Light frame construction using standardized dimensional lumber has become the dominant construction method in North America and Australia because of its economy. Use of minimal structural materials allows builders to enclose a large area with minimal cost, while achieving a wide variety of architectural styles. The ubiquitous platform framing and the older balloon framing are the two different light frame construction systems used in North America.

Walls

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 (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. The technique is variously referred to colloquially in the building trades as "stick and frame" or "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'), supports the weight of whatever is above, including the next wall up and the roof above the top story. The platform, also provides the 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 should be grade-stamped, and have a moisture content not exceeding 19%.

There are three historically common methods of framing a house. Post and Beam, which is now used predominately in barn construction. Balloon framing using a technique suspending floors from the walls was common until the late 1940s, but since that time, platform framing has become the predominant form of house construction. Platform framing often forms wall sections horizontally on the sub-floor prior to erection, easing positioning of studs and increasing accuracy while cutting the necessary manpower. The top and bottom plates are end-nailed to each stud with two nails at least 3 1/4 in. (82 mm) in length (16d or 16 penny nails). Studs are at least doubled (creating posts) at openings, the jack stud being cut to receive the lintels(headers) that are placed and end-nailed through the outer studs.

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 fibreboard, plywood, oriented strand board and waferboard, will provide adequate bracing to resist lateral loads and keep the wall square, but construction codes in most jurisdictions will require a stiff plywood sheathing. Others, such as rigid glass-fibre, asphalt-coated fibreboard, 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 country, 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.

Corners

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 the interior finish 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'.

Exterior wall studs

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. They are supported on a bottom plate or foundation sill and in turn support the top plate. Studs usually consist of 2 x 4 in. (38 x 89 mm) or 2 x 6 in. (38 x 140 mm) lumber and are commonly spaced at 16 in. (400 mm) on centre. This spacing may be changed to 12 in. (300 mm) or 24 in. (600 mm) on centre depending on the load and the limitations imposed by the type and thickness of the wall covering used. Wider 2 x 6 in. (38 x 140 mm) studs may be used to provide space for more insulation. Insulation beyond that which can be accommodated within a 3 1/2 in. (89 mm) stud space can also be provided by other means, such as rigid or semi-rigid insulation or batts between 2 x 2 in. (38 x 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 2 in. (nominal) (38 mm) lumber that are the same width as the studs.

Interior partitions

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 2 x 4 in. (38 x 89 mm) lumber spaced at 16 in. (400 mm) on centre. This spacing may be changed to 12 in. (300 mm) or 24 in. (600 mm) depending on the loads supported and the type and thickness of the wall finish used.

Partitions can be built with 2 x 3 in. (38 x 64 mm) or 2 x 4 in. (38 x 89 mm) studs spaced at 16 or 24 in. (400 or 600 mm) on center depending on the type and thickness of the wall finish used. Where a partition does not contain a swinging door, 2 x 4 in. (38 x 89 mm) studs at 16 in. (400 mm) on centre 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 2 in. (nominal) (38 mm) lumber the same width as the studs. These members provide a nailing support for wall finish, door frames and trim.

Lintels (headers)

Lintels (aka headers) are the horizontal members placed over window, door and other openings to carry loads to the adjoining studs. Lintels are usually constructed of two pieces of 2 in. (nominal) (38 mm) lumber separated with spacers to the width of the studs and nailed together to form a single unit. The preferable spacer material is rigid insulation. The depth of a lintel is determined by the width of the opening and vertical loads supported.

Wall Sections

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. (75 mm) wide and 6 in. (150 mm) long, nailed with at least three 2 1/2 in. (63 mm) nails to each wall.

Balloon framing

Balloon framing is a method of wood construction used primarily in Scandinavia, Canada and the United States (up until the mid-1950s). It utilizes long continuous framing members (studs) that run from sill plate to eave line with intermediate floor structures nailed to them, with the heights of window sills, headers and next floor height marked out on the studs with a storey pole. Once popular when long lumber was plentiful, balloon framing has been largely replaced by platform framing.

While no one is sure who introduced balloon framing in the U.S., the first building using balloon framing was probably a warehouse constructed in 1832 in Chicago by George Washington Snow. The following year, Augustine Taylor (1796-1891) constructed St. Mary's Catholic Church in Chicago using the balloon framing method. Alternately, the balloon frame has been shown to have been introduced in Missouri as much as fifty years earlier.

The name comes from a French Missouri type of construction, "maison en boulin." The curious name of this framing technique is conventionally thought to be a derisive one. Historians have fabricated the following story: As Taylor was constructing his first such building, St. Mary's Church, in 1833, skilled carpenters looked on at the comparatively thin framing members, all held together with nails, and declared this method of construction to be no more substantial than a balloon. It would surely blow over in the next wind! Though the criticism proved baseless, the name stuck.

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. It is also a fair certainty that, by radically reducing construction costs, balloon framing improved the shelter options of poorer North Americans. For example, many 19th century New England working neighborhoods consist of balloon-constructed three-story apartment buildings referred to as triple deckers.

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.

Balloon framing has several disadvantages as a construction method:

1. The creation of a path for fire to readily travel from floor to floor. This is mitigated with the use of firestops at each floor level.
2. The lack of a working platform for work on upper floors. Whereas workers can readily reach the top of the walls being erected with platform framing, balloon construction requires scaffolding to reach the tops of the walls (which are often two or three stories above the working platform).
3. The requirement for long framing members.
4. In certain larger buildings, a noticeable down-slope of floors towards central walls, caused by the differential shrinkage of the wood framing members at the perimeter versus central walls. Larger balloon-framed buildings will have central bearing walls which are actually platform framed and thus will have horizontal sill and top plates at each floor level, plus the intervening floor joists, at these central walls. Wood will shrink much more across its grain than along the grain. Therefore, the cumulative shrinkage in the center of such a building is considerably more than the shrinkage at the perimeter where there are much fewer horizontal members. Of course, this problem, unlike the first three, takes time to develop and become noticeable.

Since steel is generally more fire-resistant than wood, and steel framing members can be made to arbitrary lengths, balloon framing is growing in popularity again in light gauge steel stud construction. Balloon framing provides a more direct load path down to the foundation. Additionally, balloon framing allows more flexibility for trade workers in that it is significantly easier to pull wire, piping and ducting without having to bore through or work around framing members.

Platform framing

In Canada and the United States, the most common method of light-frame construction for houses and small apartment buildings as well as some small commercial buildings is Platform framing.

The framed structure sits atop a concrete (most common) or treated wood foundation. A sill plate is anchored, usually with 'J' bolts to the foundation wall. Generally these plates must be pressure treated to keep from rotting. The bottom of the sill plate is raised a minimum 6 inches (150 mm) above the finished grade by the foundation. This again is to prevent the sill-plate from rotting as well as providing a termite barrier.

The floors, walls and roof of a framed structure are created by assembling (using nails) consistently sized framing elements of dimensional lumber (2×4, 2×6, etc.) at regular spacings (12″, 16″, and 24″ on center), forming stud-bays (wall) or joist-bays (floor). The floors, walls and roof are typically made torsionally stable with the installation of a plywood or composite wood “skin” referred to as sheathing. Sheathing has very specific nailing requirements (such as size and spacing); these measures allow a known amount of shear force to be resisted by the element. Spacing the framing members properly allows them to align with the edges of standard sheathing. In the past, tongue and groove planks installed diagonally were used as sheathing. Occasionally, wooden or galvanized steel braces are used instead of sheathing. There are also engineered wood panels made for shear and bracing.

The floor, or the platform of the name, is made up of joists (usually 2x6, 2×8, 2×10 or 2×12, depending on the span) that sit on supporting walls, beams or girders. The floor joists are spaced at (12″, 16″, and 24″ on center) and covered with a plywood subfloor. In the past, 1x planks set at 45-degrees to the joists were used for the subfloor.

Where the design calls for a framed floor, the resulting platform is where the framer will construct and stand that floor’s walls (interior and exterior load bearing walls and space-dividing, non-load bearing “partitions”). Additional framed floors and their walls may then be erected to a general maximum of four in wood framed construction. There will be no framed floor in the case of a single-level structure with a concrete floor known as a “slab on grade”.

Stairs between floors are framed by installing stepped “stringers” and then placing the horizontal “treads” and vertical “risers”.

A framed roof is an assembly of rafters and wall-ties supported by the top story’s walls. Prefabricated and site-built trussed rafters are also used along with the more common stick framing method. “Trusses” are engineered to redistribute tension away from wall-tie members and the ceiling members. The roof members are covered with sheathing or strapping to form the roof deck for the finish roofing material.

Floor joists can be engineered lumber (trussed, I-beam, etc.), conserving resources with increased rigidity and value. They allow access for runs of plumbing, HVAC, etc. and some forms are pre-manufactured.

Double Framing is a style of framing used to reduce heat loss and air infiltration. Two walls are built around the perimeter of the building with a small gap in between. The inner wall carries the structural load of the building and is constructed as described above. The exterior wall is not load bearing and can be constructed using lighter materials. Insulation is installed in the entire space between the outside edge of the exterior wall and the inside edge of the interior wall. The size of the gap depends upon how much insulation is desired. The vapour barrier is installed on the outside of the inner wall, rather than between the studs and drywall of a standard framed structure. This increases its effectiveness as it is not perforated by electrical and plumbing connections.

Materials

Light-frame materials are most often wood or rectangular steel tubes or C-channels. Wood pieces are typically connected with nails or screws; steel pieces are connected by screws. Preferred species for linear structural members are softwoods such as spruce, pine and fir. Light frame material dimensions range from 38 mm by 89 mm (1.5 by 3.5 inches (89 mm) — i.e. a two-by-four) to 5 cm by 30 cm (two-by-twelve inches) at the cross-section, and lengths ranging from 2.5 m (8 ft) for walls to 7 m (20 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 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.

Light-gauge metal stud framing

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.

Interior wall coverings in light-frame construction typically include wallboard, lath and plaster or decorative wood paneling.

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 inches) 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.

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 diagonly across a wall is called a T-bar it stops the walls collapsing in gusty winds.

Roofs

Roofs are usually built to provide a sloping surface intended to shed rain or snow, with slopes ranging from 1 cm of rise per 15 cm (less than an inch per linear foot) of rafter length, to steep slopes of more than 2 cm per cm (two feet per foot) of rafter length. A light-frame structure built mostly inside sloping walls comprising a roof is called an A-frame.

Roofs are most often covered 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, which 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.

Structure

Light-frame buildings 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-beam (closed web trussed) joists are often made from laminated woods, most often chipped poplar wood, in panels as thin as 1 cm (3/8ths of an inch), glued between horizontally laminated members of less than 5 cm by 5 cm (two-by-two inches), to span distances of as much as 9 m (30 ft). Open web trussed joists and rafters are often formed of 5 cm by 10 cm (two-by-four inch) wood members to provide support for floors, roofing systems and ceiling finishes.

Source : http://en.wikipedia.org

Fireproofing

"Fireproof" redirects here. For the album, see Fireproof (album). For the 2008 film, see Fireproof (film).

Spray gypsum based plaster fireproofing being installed.

Circuit integrity fireproofing of cable trays, using calcium silicate boards.

Fireproofing, a passive fire protection measure, refers to the act of making materials or structures more resistant to fire, or to those materials themselves, or the act of applying such materials. Applying a certification listed fireproofing system to certain structures allows these to have a fire-resistance rating. The term fireproof does not necessarily mean that an item cannot ever burn: It relates to measured performance under specific conditions of testing and evaluation. Fireproofing does not allow treated items to be entirely unaffected by any fire, as conventional materials are not immune to the effects of fire at a sufficient intensity and/or duration.

Markets

• Commercial construction
• Residential construction
• Industrial construction
• Marine (ships)
• Offshore construction
• Aerodynamics
• Tunnel concrete walls and ceilings or linings
• Under and above ground mining operations

Applications

• Structural steel to keep below critical temperature ca. 540 °C
• Electrical circuits to keep critical electrical circuits below 140 °C so they stay operational
• Liquified petroleum gas containers to prevent a BLEVE (boiling liquid expanding vapour explosion)
• Vessel skirts and pipe bridges in an oil refinery or chemical plant to keep the structural steel below critical temperature ca. 540°
• Concrete linings of traffic tunnels

History

Asbestos is one material historically used for fireproofing, either on its own, or together with binders such as cement, either in sprayed form or in pressed sheets, or as additives to a variety of materials and products, including fabrics for protective clothing and building materials. Because the material has proven to cause cancer in the long run, a large removal and replacement business has been established.

Endothermic materials have also been used to a large extent and are still in use today, such as gypsum, concrete and other cementitious products. More highly evolved versions of these are used in aerodynamics, intercontinental ballistic missiles (ICBMs) and re-entry vehicles, such as the space shuttles.

The use of these older materials has been standardised in "old" systems, such as those listed in BS476, DIN4102 and the National Building Code of Canada.

Alternative fireproofing methods

Among the conventional materials, purpose-designed spray fireproofing plasters have become abundantly available the world over. The inorganic methods include:

• Gypsum plasters
• Cementitious plasters
• Fibrous plasters

The industry considers gypsum-based plasters to be "cementitious", even though these contain no portland cement, or calcium alumina cement. Cementitious plasters that contain Portland cement have been traditionally lightened by the use of inorganic lightweight aggregates, such as vermiculite and perlite.

Gypsum plasters have been lightened by using chemical additives to create bubbles that displace solids, thus reducing the bulk density. Also, lightweight polystyrene beads have been mixed into the plasters at the factory in an effort to reduce the density, which generally results in a more effective insulation at a lower cost. The resulting plaster has qualified to the A2 combustibility rating as per DIN4102. Fibrous plasters, containing either mineral wool, or ceramic fibres tend to simply entrain more air, thus displacing the heavy fibres. On-site cost reduction efforts, at times purposely contravening the requirements of the certification listing, can further enhance such displacement of solids. This has resulted in architects' specifying the use of on-site testing of proper densities to ensure the products installed meet the certification listings employed for each installed configuration, because excessively light inorganic fireproofing does not provide adequate protection and are thus in violation of the listings.

Pipes covered with a thin-film intumescent spray fireproofing. The intumescent expands when heated, forming a layer of insulation, which slows down heat transfer to the pipe below.

. Intumescent spray fireproofing product has expanded.

New materials based on organic chemistry are gaining in popularity for a variety of reasons. In land-based construction, thin-film intumescents have become more widely used. Unlike their inorganic competitors, thin-film intumescents are installed like paint, except that the purpose is to achieve a certain thickness, not just to apply a different colour, and do not require the concealment of structural steel elements such as I-beams and columns. Care must be taken to ensure that such products are protected from atmospheric moisture and operational heat, which can adversely affect these organic, covalently bound products. The use of DIBt approved products, which mandates testing of the effects of ageing, is prudent.

Thicker intumescent and endothermic resin systems tend to use an oil basis (usually epoxy), which, when exposed to fire, creates so much smoke, that even though these products provide enough heat flow retardation towards the substrate, they tend to be banned from use inside of buildings because of the smoke they develop when subjected to fire, and are used mainly in exterior construction, such as LPG vessels, vessel skirts and pipe bridges in oil refineries, chemical plants and offshore oil and gas platforms.

Proprietary boards and sheets, made of gypsum, calcium silicate, vermiculite, perlite, mechanically bonded composite boards made of punched sheet-metal and cellulose reinforced concrete (DuraSteel) have all been used to clad items for increased fire-resistance. Cladding is traditionally much more popular and organised in Europe than in North America. Fringe methods have also included intumescent tapes and sheets, as well as endothermically treated ceramic fibre sheets and roll materials. The latter work well but are not particularly popular due to cost reasons. Ordinary ceramic fibre, typically encased in thin aluminium foil is often used to protect pressurisation ductwork and grease ducts in North America. Such mineral wool (rock wool) wraps have been used in Europe for decades more than in North America. European construction sites tend to use much less expensive mineral wool wraps for duct fireproofing. All are qualified to the same test regime: ISO6944, with the exception that systems qualified for the North America market also undergo a hose-stream test immediately following the fire exposure in order to validate the firestop portion of the system.

Fraud

The following examples of fraud are preventable when documentation is required and checked to ensure that all installed configurations fall within the tolerances of active certification listings.

• Entraining too much air in inorganic systems, thus reducing densities, saves on materials and labour.
• Spraying inorganic spray fireproofing materials over through-penetrations and building joints that should be firestopped, not fireproofed. This practice negates fire-separation integrity. Firestops must precede spray fireproofing.
  
  

  Firestopped through-penetrations of structural beams. The installation is incomplete, as the beams are not yet treated with fireproofing. If left as-is, they will collapse, resulting in openings in the fire separation wall.
• Substitution of intumescent and/or endothermic fireproofing coatings with less expensive paints that physically resemble the passive fire protection products, sometimes involving re-use of packaging and de-canting of contents.
• The American and Canadian nuclear industries have, historically, not insisted on listing and approval use and compliance, on the basis of the use of accredited certification laboratories. This has allowed the use of Thermo-Lag 330-1, for which the basis of testing has been proven to be faulty, resulting in millions of dollars of remedial work. The Thermo-Lag scandal came to light as a result of disclosures by American whistleblower Gerald W. Brown, who reported the deficiencies in fire testing to the Nuclear Regulatory Commission. Presently, product certification of fireproofing and firestopping remains optional for systems installed in nuclear power plants both in Canada and the United States.

Common errors in inorganic spray fireproofing

• Portland cement bound sprays display a high pH level at first. This has, at times, been presumed to last indefinitely, particularly for exterior spray fireproofing of large liquified petroleum gas containers, vessel skirts and pipe bridges. The proper primer must be used. The high pH of cement-borne plasters does not safeguard unprotected common steel substrata. Ignorance of this fact, particularly in coastal regions with high salt exposures has led to rusting and delaminations of spray fireproofing on large LPG spheres and other similar installations. Proper epoxies must be used for water-resistance to prevent "soaping" when in contact with the plaster.
• The dew point calculations must be performed and considered where fibrous spray fireproofing on LPG spheres is installed. When this is not done, the dew point may be located inside of the spray fireproofing, which has resulted in ceramic fibre based sprays' becoming saturated with water.
• Excessive mixing of cement-borne fireproofing results in having the cement stone formed and completely spent while still mixing, which causes a "spider-web" appearance of the finished plaster, because there was little or nothing of the binder left to actually "set" or "cure" when finally placed. This reduces the plaster to a "sand-castle" quality.
• Spray fireproofing cannot be sprayed onto vibrating substrata, which can dislodge and weaken plasters.
• Fresh cement plasters should be covered to reduce premature escape of water by exposure to wind and heat, resulting in lesser quality fireproofing plasters. The water is needed to form cement stone inside of the plaster.

Work staging

Spray fireproofing products have not been qualified to the thousands of firestop configurations, so they cannot be installed in conformance of a certification listing. Therefore, firestopping must precede fireproofing. Both need one another. If the structural steel is left without fireproofing, it can damage fire barriers and a building can collapse. If the barriers are not firestopped properly, fire and smoke can spread from one compartment to another.

Traffic tunnel fireproofing

Traffic tunnels may be traversed by vehicles carrying flammable goods, such as petrol, liquified petroleum gas and other hydrocarbons, which are known to cause a very rapid temperature rise and high ultimate temperatures in case of a fire (see the hydrocarbon curves in fire-resistance rating). Where hydrocarbon transports are permitted in tunnel construction and operations, accidental fires may occur, resulting in the need for fireproofing of traffic tunnels with concrete linings. Traffic tunnels are not ordinarily equipped with fire suppression means, such as fire sprinkler systems. It is very difficult to control hydrocarbon fires by active fire protection means, and it is expensive to equip an entire tunnel along its whole length for the eventuality of a hydrocarbon fire or a BLEVE.

Concrete exposed to hydrocarbon fires

Concrete, by itself, cannot withstand hydrocarbon fires. In the Channel tunnel that connects England and France, an intense fire broke out and reduced the concrete lining in the undersea tunnel down to about 50 mm. In ordinary building fires, concrete typically achieves excellent fire-resistance ratings, unless it is too wet, which can cause it to crack and explode. For unprotected concrete, the sudden endothermic reaction of the hydrates and unbound humidity inside the concrete causes such pressure as to spall off the concrete, which then winds up in small pieces on the floor of the tunnel. This is the reason why laboratories, which conduct fire-resistance testing, such as ULC, iBMB TU Braunschweig, which headed the "Eureka" [2] project, or Underwriters Laboratories insert humidity probes into all concrete slabs that undergo fire testing even in accordance with the less severe building elements curve (DIN4102, ASTM E119, BS476, or ULC-S101). Only once the humidity is low enough, will a fire test be conducted because otherwise explosions would result. The culprit is the hydrates and unbound humidity in the concrete, and this is not new. Another prime example of this is the fact that walls constructed of lost plastic forms, which are filled on site with concrete cannot withstand the testing required of a loadbearing Firewall (construction). During the fire test, these walls are subjected to a load, which then leads to such a forceful explosion as to shear the wall with thunderous noise. A hydrocarbon fire is much more rapid and severe than a typical building fire. Consequently, concrete is much more vulnerable and must be protected in order to remain operable during a hydrocarbon fire. The need for fireproofing was demonstrated, among other fire protection measures, in the European "Eureka" Fire Tunnel Research Project, which resulted in building codes for the trade to avoid the effects of such fires upon traffic tunnels. Cementitious spray fireproofing must be certification listed and applied in the field as per that listing, using a hydrocarbon fire test curve such as the one that is also used in UL1709 [3].

Fireproofing concrete tunnel linings

In essence, this is really not much different from protecting structural steel or electrical circuits or valves. The systems must be installed in accordance with the requirements of the certification listing. Heat transfer into the item to be protected must be limited. This is accomplished by the use of firm fireproofing products, such as higher density fireproofing plasters or fireproofing boards, such as those made of calcium silicate or vermiculite. Other things to be kept in mind are as follows:

• Existing traffic tunnel surfaces that are to be fireproofed must be cleaned to remove any substances that may impair proper bonding.
• As traffic emissions darken new fireproofing products, light-reflecting coatings should be considered. They should be easy to clean, compatible with the substrate, and the combination of the fireproofing with the paint must be capable of absorbing the kinetic energy of spray cleaning.
• In mountain tunnels, a space should be created between the fireproofing and the stone, for water traveling downwards through the mountain to be drained off, to avoid the formation of icicles and damage to the fireproofing system.

Trade jurisdiction on unionised construction sites in North America

• Structural Steel and Concrete Substrata: Plasterers
• Electrical Circuits: Insulators
• Ductwork: Insulators

Fireproof Vaults

The traditional method for constructing fireproof vaults to protect important paper documents has been to use concrete or masonry blocks as the primary building material. In the event of a fire, the chemically bound water within the concrete or masonry blocks will be forced into the vault chamber as steam. The steam will soak the paper documents to keep them from burning. This steam will also help keep the temperature inside the vault chamber below the critical 350-degree Fahrenheit (176.7-degrees Celsius) threshold, which is the point at which information on paper documents is destroyed. The paper can later be remediated with a freeze drying process, if the fire is extinguished before internal temperatures exceed 350-degrees F.

This traditional vault construction method is sufficient for paper documents, but the steam generated by concrete/masonry structures will destroy contents that are more sensitive to heat and moisture. For example, information on microfilm is destroyed at just 150-degrees F. (65.5-degrees C. a.k.a. Class 150) and magnetic media (such as data tapes) lose data above 125-degrees F. (51.7-degrees C. a.k.a. Class 125). Fireproof vaults built to meet the more stringent Class 150 and Class 125 requirements are called data-rated vaults.

Source : http://en.wikipedia.org