Does anyone have links, details, pictures or drawings showing methods for attaching joists to steel beams please?
I am hoping to take out a wall which simply supports overlapping ceiling joists in a single storey extension. But, I don't want to install a beam below the ceiling and would rather it fitted within the depth of the joists (projecting above into the loft space depending on the beam depth).
So, how do I connect joist ends to the support beam?
TIA
Phil
Joist hangers?
Don't forget that any steel framework has to be fireproofed.
Christian.
Thanks Christian, but I don't see how the joist hangers (usually nailed of course) get fixed to the I section beam! This is the sort of detail I am looking for guidance on.
Phil
Simple metal hook shaped things that screw to the timber joists, after being placed over the far edge of the beam. Or flat metal straps that straddle the beam and screw to the ends of the joists on either side, if they line up together that is. With two sets of joist ends coming from either side of the web on an " I " (eye) Beam, the straps help hold the beam, and beam helps hold the joists. It might need BCO and Structural Engineer Calcs' before you get insurance cover though.
Hi,
I'm not sure if it is possible for your situation, but I have done this with the ends of the joists shaped to fit into either side of the "I" of the beam - and before anyone says anything - it was approved by the structural engineer and BCO - worked a treat. Difficult do do unless you are completely removing the ceilings in both rooms and the dwangs between the joists but an option none the less.
Alan.
They can be bolted to the steel, or hung over the top.
Christian.
Alan
Thanks - can you tell me the width of the section you used please? I was under the understanding that 75mm of bearing length was required to the end of each joist. This would result in a larger than necessary section for the job in hand.
Also what is a dwang?
2nd Also - what did you do about fire proofing of beam in this instance?Thanks in anticipation
Phil
I was going to use an 8x4" steel beam at one time, with joist hangers for the wooden joists. The BCO suggested I forgo the joist hangers and notch the joists onto the 50mm bearing of the section.
I enclosed the exposed faces of the beam with two layers of 12mm plasterboard.
Were you given any recommendations for end support of the steel beam? Is a concrete lintel/padstone needed? Do the ends have to be secured in any way or do they just sit on the supporting wall? I believe it is usual to build the ends in?
TIA
Phil
IIRC it was 150mm bearing on a padstone (cut from concrete lintel) built in.
Thanks Mr B Thumbs
I believe I have enough information etc to size beam and submit proposals now.
Phil
Hi,
I don't have the exact size to hand but looking at standard size information on the web, I think it was a 203x133. I guess that would give you about 60mm bearing by the time you take the beam thickness away. I've no idea if this is a larger than necessary section.
A dwang is the Scottish term for noggin. The short pieces of wood which go between the beams to stop sideways movement.
Intumescent paint for fire proofing.
The end of the beam sits on a pad stone and is then concreted in.
Alan.
Thanks Alan
I'll run the sums and check beam size, deflection etc. As this is only taking ceiling materials, light storage loads I was looking at 7 x 4 which affords slightly less bearing than your 133.
Phil
When they converted my house into a house, they bolted huge timbers parallel to the beams, notched them, and put the joists in there.
I suspect you could do the same with smaller timbers and joist hangers.
We had all that exposed when reordering the rooms recently, and the BCO was perfectly happy with it.
Surely that's only if it's exposed or goes through a fire break? My steel[*] has still got the 1930s red oxide on, and nothing else and - as I said - the BCO was happy with it.
[*] the house is a converted telephone exchange, the roof and upper floor supports are two steel A frames.
You put the ends of the joist into the web of the beam, or put another way, into the middle of "I" shape.
Rick
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