ROR Gantry Framing

[Allan]

Any engineers out there? :) I’m trying to work out how many columns to use to hold up the gantry rail section that the roof rolls onto. I would prefer the minimum number, but obviously don’t want to end up with an unstable structure that I have to retro fix.

Roof is 7m x 5.5m and will weigh around 600kg. The columns will be 140x140 supporting a 190x45 timber on edge with the steel track sitting on top of the timber.

Two columns means a 3.5m span between columns. I could bring the end column in by 1m and cantilever the track off the end, so the span drops to 3m. Three columns drops the span to around 2.3m.

Any guidance will be appreciated.

[Wilso]

I'm just a simple carpenter, ...like God :rofl:

You need to select what type of timber for the beam 190x45 to help you in the right direction. 3.5m span is too far from memory.
Permapine Pine, tru-pine, lvl (laminated veneer lumber), hardwood etc....
-Continuous span you can counter leverage.
-Lvl/hardwood will span further.
-Your local timber supplier can help you out.

Cheers
(for that size structure council would req. engineers calculations etc)

[Allan]

Thanks Darren. In the absence of any conclusive guidance, I will do three columns for a 2.3m span, just to be on the safe side.

The observatory is in a remote spot, and very neatly avoids all the requirements for council approval. Hence no engineering drawings.