Hare-brained scheme for a hanging beam

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Originally Posted by silentC

Too late I already glued two of them edge to edge. I figured if it's too flexy once I hang the joists off it, I'll just get up there and glue the third one on top. Some how, I don't think it will be necessary though ;)

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Why not get some gang nail plates and hammer them every 600mm along the length on each side.

To get the true strength of the full depth of the double beam, you need enough tensile/shear strength in the joint. Not sure if the glue would be enough. Gang nails would help, but are ugly. You can drill vertically through the two at regular intervals then bolt them together with say 12mm bolts - with glue, 500 centres should do it. Use cup head bolts, with the heads down, that way the nuts can be counter bored and hidden whilst the heads would look Ok.

Food for thought.

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Originally Posted by dai sensei

To get the true strength of the full depth of the double beam, you need enough tensile/shear strength in the joint. Not sure if the glue would be enough. Gang nails would help, but are ugly. You can drill vertically through the two at regular intervals then bolt them together with say 12mm bolts - with glue, 500 centres should do it. Use cup head bolts, with the heads down, that way the nuts can be counter bored and hidden whilst the heads would look Ok.

Food for thought.

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If it is up in the roof it wouldn't matter how ugly it looks as long as it works.

Thanks Neil, that's exactly what I have done. The beam is up. I've bolted it through with 1/2" cup heads, nuts down. The reason I did that was a) so I wouldn't bang my knees on the bolt ends when I'm up there and b) in case I have to add the third length to the stack down the track. I can undo the nuts, pull the bolts out and replace with longer ones without having to disturb the ceiling.

It's up there and straight as a die at the moment, but I haven't hung anything off it yet.

Silent C What is this joist span book you speak of and where can I get a copy?:confused:

It's the Hyspan span tables. Download as a PDF from http://www.chhfuturebuild.com/WSMApa...0209-1,00.html

Note this is only for LVL. You'd have to refer to the NSW Framing Manual (or similar in your state) for standard timber span tables.