tall, narrow column- Am I building too light?

[Uncle Dirtnap]

I am excited to help the local high school with another production - 'Forever Plaid' this time. Wee!

We are going with a very simple set - basically tall, narrow columns. 16' tall, 2' wide, and maybe 8" deep. There will be decorative back about 6" wider on each side, and some side flutes (think deco) further down but these will not really be structural.

My plan is to build 2 boxes (8'x2'x8") out of 1x2 framing and attach them together, attach a 36"x8' strip of 1/2 ply. then I can attach them to a 16' 2x4 with a brace/jack. The other surfaces will be covered with luan, which should stiffen then up.

Should I stagger the joints, and basically make the luan and plywood 4', 8', 4' instead of 8' and 8'? pointless?

The side flutes will 6" wide luan riped 8' and have a pleasant radius on the end. The will be various heights and attach with a 1/2 spacer to the plywood back.

I need to give some thought to the base - I'm thinking 2'x4' ply, or maybe 4'x4'. Hmm.

So am I building this too light? I always want to go light when it is tall, but I never know where to draw the line. At the same time, as always, there is almost no time to build so it needs to stay simple and informative for the high-school kids.

Last question - if I drop the height down to 12, does that change anything? Make it all easier?

Thanks in advance for you opinions!

-RJ

 

[Doug Lowthian]

Off the top of my head what if you build the bottom 2-3 feet heavy, maybe 2x4 frame and the top 1x 2 framing. Bottom weight it. As I type this, another idea came; assuming the column is hollw, could you put a cement block in the bottom on a "floor" attached to the framing?

 

[DRU]

Do you have the ability to attach at the top? Do they move or are they stationary? If they move and weight is an issue, try foam. Get some 2" pink foam, cut them 3/8" under 2' wide, stagger the seams into a 16' tall foam column 8" deep, then skin with Lauan. Spackle, sand, paint. Plywood base with a sandbag and you'd be good.

I've done 20ft-ish columns as small as 8"x8" out of Lauan and 1x1, glued and stapled. They were faced on all four sides, and I had the seams of each side staggered 2ft. I also had the 1x1 inside staggered (it was a nightmare keeping track of all the seam locations), but attached at the bottom and at the top worked fine. They also intersected other scenic elements, so they had some other support, but they were at least a 12' span above to the catwalks.

 

[BillConnerFASTC]

I like the idea of foam and ghetyo fibreglass. They'd be stiff enough but still keeping them upright. Maybe something like a boom base and short boom.

 

[kicknargel]

If you're running that 16' 2x4 on edge up the back, solidly connected and held by a jack, I think you're good. I'd build the rest as light as possible and let the 2x4 provide the stiffness.

I didn't quite follow what the 3' x 8' ply was for.

 

[Hutcoy]

Staggering seams always helps with ridigity. I just built a set with fullstage roof trusses that were 8x8 beams. Built them out of 1x3 and lauan, and they held together solid. Columns for the vertical beams were the same. I like the idea of beefing up the bottom 4'.

 

[Uncle Dirtnap]

Thank you all! They are coming together rather nicely - I ended up with a box 14' long, 14" wide and 6" deep framed by 1x2s and skinned with luan on 3 sides. These are stiff as anything and are laughably light - probably 25 pounds a piece. The will be mounted to 2" plywood, and jacked. The 2x4 all the way up the back is seeming like overkill, but we will see. I'll get some pictures and sketch up shots up here soon.

Thanks again!

-rj