How much of joist into steel beam?

[gasbusters]

Could someone please advise.

Im about to put the loft floor joists into the steel beams.

The joists are c24, 75mm x 200mm. Length is 4.7 meters.

The steel beam is 200 x 200mm x 46kg

My question is, how much of the wooden joist needs to be sitting on the bottom flange of the steel beam?

Ive read previously that you need 40mm minimum? Is this correct? I was thinking of having mine about 70mm sitting on the steel?

Any advice is much appreciated

 

[Deleted member 174758]

We always work to minimum 50mm bearing

 

[gasbusters]

We always work to minimum 50mm bearing

I was thinking i could get mine in about 65mm

 

[Nozzle]

Surely none of it should be sitting on the flange whatsoever...

It sould be attached to a timber which is bolted to the vertical. (I'm no builder or SE... but it's what I've learned from other contributors on this site)

Nozzle

 

[gasbusters]

Surely none of it should be sitting on the flange whatsoever...

It sould be attached to a timber which is bolted to the vertical. (I'm no builder or SE... but it's what I've learned from other contributors on this site)

Nozzle

No i was told by the architect you can simply notch the joists and slot it into the steel beams by resting it on the flange

 

[martin hill]

Most i have seen use this method.

 

[Deleted member 174758]

In my recent experience (i.e the last 18 months) both approaches are in use. Seems to depend on the individual SE or architect as to what we end up doing.

 

[Deleted member 174758]

I was thinking i could get mine in about 65mm

What I was trying to convey was that the minimum bearing should be 50mm, so 65mm would be grand. Sorry for any misunderstanding

 

[Nozzle]

No i was told by the architect you can simply notch the joists and slot it into the steel beams by resting it on the flange

See the post from @martin hill

 

[martin hill]

What I was trying to convey was that the minimum bearing should be 50mm, so 65mm would be grand. Sorry for any misunderstanding

Go for the bolt on bearer. You are not notching the joist and the joist weight is being transferred to the beam not the flange itself.

 

[gasbusters]

Go for the bolt on bearer. You are not notching the joist and the joist weight is being transferred to the beam not the flange itself.

But is the flange not designed to take this weight?

The beams are oversized, 200x200mm x 46kg, length is 5.8 meters long

The joists are 200mm x 75mm length 4.7

 

[tony1851]

Just supporting them off the bottom flange is fine.

 

[cdbe]

I did mine like this:

The steel is a 150 so bearing is about 70mm, noggins are based on the info below which is an nhbc document (may be overkill but I'm building on a building notice so don't want to create problems).

 

[Deleted member 174758]

Go for the bolt on bearer. You are not notching the joist and the joist weight is being transferred to the beam not the flange itself.

As stated above the flange is normally sufficiently strong to carry the predicted load and in any case in many cases the infill will end up resting on the bottom flange if properly sized thus transferring at the very least part of the load from the supported floor into the flange. It seems that the only time we do the bolted infills is in heavily loaded floors where there is a concern about the point loads being transmitted into the flange, e.g. landings on public building stairs etc. In addition there is a cost implication when infilling with a bolted-in timber joist and fixing joist hangers to that - both your labour and materials costs will be markedly higher than it will be for simply notching but the bearing surface for the joist ends will be much the same. In order to ensure lack of twisting the gaps between joists are always unfilled with snug fitted noggins which are toe nailed in place through into the abutting joists. This is arguably less likely to permit twist under load (and so ensure greater floor stiffness) than dropping joists into thin metal hangers without the addition of solid strutting.