Wood joist spacing

[oemodm]

In the last image, the spacing are fine for 1st floor, in fact. I'm just curious about the vertical wood supports, 1 per floor joist, or can be less?

Added to that, another idea to see if anyone has a take on it. Rather than using steel, is there a simple way to make some sort of high strength truss A? It could be 60cm deep...no problem. B is the 76x175 joists at 400mm spacings.

B could be several 75 x 225's bolted together to make a depth of 600mm. Just thinking out loud & understand need to work out the weights.

 

[Norcon]

You're over thinking this.
All you need is two 8x4 girders with the joists placed in the webbings.
Then no height lost.

 

[RonnyRaygun]

If you really want to use timber, designing for a domestic floor load of 1.5kN/m2, you would need a timber section 300mm deep by 100mm wide in order to span 5.0m.

Of course, you probably won't be able to source a timber section 300mm deep, and attempting to somehow screw 150x50mm sections on top of and beside each other would be difficult.

As I said previously, you should be able to get engineered joists to work, but you would have to check with the manufacturers to find out what size would be required.

 

[tony1851]

Even discounting the self weight of the beam and floor, suspect a 300x100 C16 on that span would still be over-stressed (around 6.25 N/mm^2?).

Better off with steel IMO.

 

[oemodm]

Hi guys,

I've decided to go with this option:

The 75 x 225 cover the 5 metre span. I'll be using douglas fir beams.

According to http://www.jrpcad.co.uk/Pages/Timber_Span_Tables.aspx - 75 x 225 should be fine with a 5.1 metre span, at 40cm spacing.

Could I get some final input on this, I know it's been dragged out.

thanks / simon

 

[noseall]

Don't forget 1/3rd span bridging between joists.

 

[oemodm]

thank you.
I did overlook that completely.

 

[oemodm]

You're over thinking this.
All you need is two 8x4 girders with the joists placed in the webbings.
Then no height lost.

Apologies for dragging this up from the dredges. Could someone refer me to a beam spec or beam BSI number? or advise what kind of material thickness it should have, I'm looking to buy this next week. many thanks / simon

 

[Norcon]

Just go to a steel stock holder and ask them for a standard 8" x 4" girder cut to size.

I'd use 4" x 4" box section for the stanchions with 4mm wall.

 

[oemodm]

Just go to a steel stock holder and ask them for a standard 8" x 4" girder cut to size.

I'd use 4" x 4" box section for the stanchions with 4mm wall.

Thanks for replying.

I'm going to import with other bulk materials. Will just make sure is 23kg/m. You lost me on the stanchions and 4mm wall.

>>>>>>>>>>>

Would it be OK in your view to, rather than build brick pillars to support the girders, instead to prop it up with a wood beam (75 x 225 section, or 63 x 175?) standing vertically at each end. The vertical wood beam bolted to the stone wall. The wood beam could be notched at the top for the girder to sit in. This would be quicker than building brick pillars.

>>>>>>>>>>>>

thanks / simon

 

[Norcon]

I wouldn't faff around with timber. I'd fabricate it in the workshop in a few hours then to site and bolt it up. I've got the steel all sitting there beside 40 tons worth of industrial 3 phase metal working machinery in a purpose built facility at my disposal.
A days work at most. Mobile welder and mag drill to site for any incompatibilities.
You could have it cased in with decorative timber/panelling later if you want.
Job done.

 

[oemodm]

I'm very impression.

I don't mind faffing, if its easier for me. Propping him up using 63 x 175 beams at each end would be easiest for me, would propping him up be ok?