Loft conversion
- Thread starter Chipy77
- Start date
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A flitched beam generally consists of a steel plate sandwiched between two timber joists.
What you have described is a timber trimmer built up out of three joists. If they are well-bolted together, they will be fine to support your floor joists off hangers, assuming the span is not too great.
What you have described is a timber trimmer built up out of three joists. If they are well-bolted together, they will be fine to support your floor joists off hangers, assuming the span is not too great.
7 metre span on to timber structural walls hanging 4 metre joists
If the span of the trimmer is 7m, three 9x2s will not do, due to excessive deflection, and the timber may also be over-stressed.
On that span, you would realistically need steel.
On that span, you would realistically need steel.
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So revert back to a flitch beam 2. 9x2 and a steel this is sitting on timber structal wall or go 3 9x2 and two steel plates
Even with one or two steel plates, a flitched beam of steel plate(s) and timber would not be sufficient.
You really need to consider steel, and on that span, from back-of-envelope calculations, you would be looking at something like a 254x147 UB or a 203x203 UC section.
7m is just too long to do in anything other than a conventional steel beam. Ideally you need to get an SE to do proper figures for you. Yes. it will cost, but it will also cost when you end up with a floor like a trampoline.
You can support a steel beam on a structural stud partition if necessary, subject to a suitable bearing plate.
You really need to consider steel, and on that span, from back-of-envelope calculations, you would be looking at something like a 254x147 UB or a 203x203 UC section.
7m is just too long to do in anything other than a conventional steel beam. Ideally you need to get an SE to do proper figures for you. Yes. it will cost, but it will also cost when you end up with a floor like a trampoline.
You can support a steel beam on a structural stud partition if necessary, subject to a suitable bearing plate.
Can the steel be joined in the middle using correct joiners then in cased with 9x2 in web
Yes, you can have it spliced, but the connection (usually using top and bottom plates and a web plate), requires some drilling and bolting, and needs to be properly sized.
Some SEs don't like splicing in the middle because the bending stress is greatest there, but with just a floor load in your case, it should be practical.
Then looking to brace rafters to it and remove existing support
Yes, it's still possible to keep the splice in the middle. The SE would work out the maximum bending moment under all the loads and design a splice to resist the stress caused by that bending moment.
But it could require a fair number of bolts, and long plates, to give the strength required.
You also have to use pre-loaded bolts (aka 'friction-grip bolts') which can be tightened so tight as to clamp the plates together to stop them moving. If you used ordinary black bolts, the clearance holes would allow the beam to bend too much.
As advised, if you go down this route, you do need the input of an SE.
But it could require a fair number of bolts, and long plates, to give the strength required.
You also have to use pre-loaded bolts (aka 'friction-grip bolts') which can be tightened so tight as to clamp the plates together to stop them moving. If you used ordinary black bolts, the clearance holes would allow the beam to bend too much.
As advised, if you go down this route, you do need the input of an SE.
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