“My dad told me about them!”: Flitch beams
Image above courtesy of Torquay Town Hall
You may have come across flitch beams. They were most commonly used as a supporting lintel over shop windows and larger spans where timber alone couldn't work.
Typically, the flitch beam is made up of a steel plate sandwiched between two timber beams, the three layers being held together with bolts. Further alternating layers of timber and steel can be used to produce an even stronger beam. The metal plate within the beam is known as a flitch plate.
Flitch beams are much lighter and cheaper than steel and will still allow fixing of surrounding framework and carcassing by nails or screws.
Are flitch beams still suitable?
Today larger spans can be achieved with composite and Glulam beams that are even lighter and less labour intensive. However the concept, which had its heyday in the early 20th century when there were post war shortages of steel, still offers versatility in design - particularly for roofing and loft conversions.
Roofs can be strengthened by upgrading existing purlins into flitch beams to take the additional roof tile weights without having to strip back the roof. Floor depths can be minimised as they require much less depth than a timber beam for the same strength. Ridge beams permit notching and easy fixing of rafters.
Your structural engineer will be able to design the steel plate and timber required and you can then order the plate predrilled, move the bolted beam into place or lift the components separately and connect them in situ.
They knew what they were doing in them olden days!
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