huangyhg

can i use a steel beam instead of wood
i would like to know if i can use a steel "i section" beam instead of a wood beam?. if so what sizes do i need?. the wood beam is 47mm x 200mm and 7 meters long it is being used for a floor joist in a house
a timber beam 7.0m long of section size 47x200mm sounds greatly undersized. deflection could be the main critera here. at what spacing are the beams at and how much load do they have to carry
kieran
the beams are 600mm apartunsure about the load the job in hand is a loft conversion which is going to have two bedrooms
i would suggest 356x171ub51 beams at 4000mm centres spanning 7000mm with timber joists spanning 4000mm between beams. ensure joists are fixed into web of beam to provide lateral restraint. joist sizes would typically be 47x195mm softwood joists at 400mm centres (thats what we use in ireland)
kieran
hi kieran
thanks for your help
lee
those sizes sound about right. however, the steel beam should be positioned slightly above the existing ceiling joists otherwise when the beam deflects under full imposed load it will touch the existing ceiling joists and transfer the load onto them.
i would stress that any coversion works of this nature should be designed and specified by a suitably qualified structural engineer.
thanks for your advice ajuk
lee

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