Can you hang a beam under a single truss?

[toolsntat]

Most I dare say would just do this but easier to ask.....
Span is 6.4 metre and the 200mm x 100mm s/w carcassing beam in 2 halves (sorry lengths) is to be positioned up to the ceiling directly under it.
Let into walls at each end.
I wouldn't necessarily be putting any fixings into the truss timber.
What do you reckon?
Cheers Andy

 

[MikeG.]

Struggling to understand this.

You've got a trussed roof with 6.4m span, right?

You then want to hang a beam underneath it...........spanning the same way? But the beam is in two halves (so if it spans the same way they are either two beams 3.2m long, or two 100x100s @ 6.4m+ long).

Further, you aren't necessarily going to be making a fixing to the truss. Does this mean you are only interested in whether the truss will take the load in the temporary situation as you haul the beams (plural) up into place?

 

[toolsntat]

Thanks Mike.
Sorry, in 2 lengths 200x100 directly under and to be a permanent feature.
Planning to use u shaped straps over topside of bottom truss timber and coach screws to pull up through to ceiling.
Cheers Andy

 

[MikeG.]

Right, so this is just about hanging a dead weight from a single truss. The weight (the new beam/s) don't help structurally because they don't span.

A structural engineer would ask for details of the truss (design, thickness of bottom chord, spacings etc), and if you are at all worried you should get confirmation from an engineer that what you are proposing will be OK. Without those design details, sizings etc, I would suggest at the very least that you share the load of this new beam over adjacent joists rather than placing it all on one truss. You can do this by putting cross-pieces* above the bottom chord, at right angles to the chord, spanning onto adjacent truss chords. Share it out over the trusses either side and you've reduced the forces on that one middle truss to one third of what they would otherwise have been. This is the equivalent of reducing that beam to 100 x 65. No-one would be too worried by that sort of load, I reckon.

*I reckon 100x50 on edge will be plenty, and put one at each of your fixing locations of the new beam to the new truss. Even better if you can get the U bolt strapping detail to go over the top of these new cross pieces.

 

[toolsntat]

OK Mike appreciate your input, I'll use some cross timbers to spread the load and incorporate the fixing to them.
Cheers Andy

 

[Sheffield Tony]

Can't you still get those rather fetching glue-on polystyrene faux-wood beams ? Save a lot of work (Ducks and runs for cover ... :lol: )