![]() The method for calculating the size of a flitch beam to be used in construction is straightforward, using the transformed-section method. This allowed the appearance of wooden columns, while providing the necessary strength. Glulam beams were used to support the second floor and the roof. Flitch beams were used as columns in a two-story new construction. The resulting flitched beam was then secured with resin and bolts, preserving appearance while providing strength. An adaptive use project in the UK, changing stables into offices, required cutting the beam supporting a floor down its entire length, and then inserting a similarly sized steel plate. Modern uses Visual description of how the strength of a flitch beam is measuredįlitch beams are currently mainly used in historic renovations, where they can be used to reinforce aged lumber supports, or for aesthetic purposes, where exposed beams with the appearance of wood and the strength of steel are required. 25.2 pounds (11.4 kg) for a flitch beam), decreases the viability of the system. This, coupled with a much increased self-weight of the beam (11.4 pounds (5.2 kg) for engineered wood vs. Engineered lumber can be cut to length and installed much like sawn lumber the flitch requires shop fabrication and/or field bolting. For example, comparing the capacity of 2 beams spanning 18 feet:Īllowable Applied Load In Pounds Per Linear Footģ½ʺ × 11¼ʺ laminated veneer lumber (LVL) memberĢ × 12 flitch beam constructed of ½ʺ steel plate with two laminations of #2 SPFĪdditionally, use of this type of beam has greatly declined due to the high cost of labor. With the advent of high-strength engineered lumber, the advantages of flitch-beams disappeared. The article also cites the fire-retardant character of the flitch beam, “in case of a fire would not probably affect the iron until the wooden beams were badly burned.” After performing calculations the beams compare as follows: This would give us, to be supported by the girder, a floor area of 12’ x 25’ = 300 square feet" and 31,500 pounds of load. An 1883 article from The American Architect and Building News compares three alternatives in a hypothetical railway station "in which the second story is devoted to offices, and where we must use girders to support the second floor of 25-foot span, and not less than 12 feet on centres if we can avoid it. ![]() With the availability of affordable steel, flitch beams became a way to strengthen long-span wooden beams cost-effectively while taking up less space than solid wood. ![]() In the 18th century, before the availability of steel beams, pine beams were flitched with hardwood such as oak. ![]() Similarly, a wooden beam was flitched by cutting it lengthwise one half was then rotated 180 degrees both longitudinally and laterally to ensure that any defects were separated. "Flitch" originally referred to a slab of bacon, which was cut into strips lengthwise. Flitch beams were used as a cost-effective way to strengthen long-span wooden beams, and have been largely supplanted by more recent technology. The metal plates within the beam are known as flitch plates. Further alternating layers of wood and steel can be used to produce an even stronger beam. In that common form it is sometimes referenced as a steel flitch beam. Typically, the flitch beam is made up of a vertical steel plate sandwiched between two wood beams, the three layers being held together with bolts. Visual description of how a flitch beam is constructedĪ flitch beam (or flitched beam) is a compound beam used in the construction of houses, decks, and other primarily wood-frame structures.
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