Roof Dilema.

[JPNortham]

Hi,

I've got a 20mx20m area 3m off the ground and I need to make a roof for it.
The size can't be changed.
It can't be supported anywhere in the centre, but as many supports as I like on the perimeter or further out.
It has to have a slight angle on it to let rain run off, and has to be strong enough to support a lightweight hanging wooden roof.
Can be made from anything, but my first thought was wood.

It's for a film set, and I'm at a loss.
Any ideas??

Cheers.
John.

 

[oilman]

20m x 20m is HUGE!!! and especially with no supports, you will need a structural engineer, not a diy site IMO. Cantilevers come to mind, but so do law suits.

 

[Jasonb]

Even with structural steel the depth of the members (lattice beam?) would seriously eat into your 3m of clear head room.

A timber grid shell may span that distance but would not work with a flat roof and it needs a lot of specialist design. Same for laminated timber portal frames

If the roof is outside don't forget to have calculations done for wind and snow loadings by a qualified engineer as they are a major consideration.

Jason

 

[JPNortham]

That grid shell looks nuts... and expensive.
Maybe woods not the answer, gotta think a litlle simpler.
Thanks for the advise.
J.

 

[big-all]

you will need planning permision as its greater than 30square mtr

you will probably need about 20 to 40 tons of steel

in other words your idea will cost you thousands of pounds and need to use steel construction simmilar to a big warehouse with your flat roof supported by cables from the "A" frames above

 

[masona]

I'm wondering if it's possible to use modular beams and scaffolding and pitch it like a roof(?) or a big warehouse or aircraft hanger may hired it you.

 

[joe-90]

It's a crazy idea that isn't even worth thinking about. It'll never get off the ground (unless it's windy).

 

[JPNortham]

Ok, so woods out of bounds for something this size...

As for planning permission, the University is dealing with that. There dealing with the legal side of it all and I dont see a scrap of paperwork (think i might have the better end of the deal here...)

The structure only has to be up for 6 months while we shoot. If I ignore the suspended roof, then maybe taught 4mm winch wire cross hatched across the top of the structure at a slight angle down, then waterproof sheets strapped to the mesh in a roof slate style to let the water run off, proof the sides of the scaffold, and then ratchet strap the bugger to the ground?
Sound feasable?

 

[masona]

What about hiring the Air Domes? I have seem them over the bowling green and tennis etc. I have no idea about the price!

 

[Deluks]

It will be much cheaper and easier to use supports on the inside of the structure. Get them digitally removed from the video afterwards, yes that will cost but nowhere near as much as an engineered solution without supports. You could also maybe paint the supports a certain colour to assist with chroma keying when editing the footage.

 

[imamartian]

why not digitally put a roof in?

 

[JPNortham]

Hehe, I had a look at the air domes, they're a little out of my range at over £2000, and I'm crap at CG so thats out the window!! And following the death of my last module the less greenyscreeny i do, the happier i am! Think i might just buy a marquee! Or maybe a circus tent...?

 

[big-all]

i recon for 6 months hire you will pronably need in excess £4000 cos they aint cheap

http://www.northernmarquees.co.uk/

 

[Hitachimad]

Youve no chance of making a simple steel rafter and purlin roof for as little as that
The sahllower the angle, the bigger the beams youll need.
Thats a little permanent anyway.

They make some pretty impressive structures from scaffolding these days, something along the lines of what they put over large buildings when re-roofing..... something to explore?

Corus have a division that specialise in modular roof construction....Corus HiPoint

But i think the most cost effective, would be a clearspan marquee, wouldnt be convinced that one would be capable of supporting much apart from its self though.







Again, no idea of the cost.

 

[Deluks]

I wasn't implying that you do the digital editing yourself, but get a pro company involved. Worth getting some quotes at least, so you compare with the cost of building what will essentially be the millennium dome's little brother.

This question shouldn't really be in the carpentry forum, it should be in the 'beyond-the-scope-of-DIYer-and-99%-of-builders' forum.

Maybe you should get in contact with Challenge Tommy Walsh?

or these guys?