steel box required for gates

[grumpy grandad]

Hi folks, I'm looking for some advice for my gate making project that I hope to get started over the Christmas break. I'm going to make a pair of gates 6ft high to span a 9 ft from box section and birch plywood. Now I have a bit of ERW box in the garage left over from another project and it's nice stuff to work with and fancy using the same but another size, so could someone kindly offer there advice and tell me if I can purchase 100mm x 40mm x 2mm ERW box or as close too as poss. and where I can get a good price and what grade steel should I ask for ?
Many thanks
Oh forgot to mention I'm near Ringwood.

 

[dan.taylor.1]

100x50 will be the nearest, never seen 100x40, next down is I think 80x40? mild steel will be fine, you want to make sure its well braced too, nowt worse than a sagging gate after 6 months, unless you make sure hinges are fully adjustable!

Dan

 

[julianthegypsy]

I'd have used 3mm section for strength myself, but maybe others would think differently?

 

[Lawnmowerboy]

2 will be fine. 3mm will make it stupid heavy and sag more that it would in 2 mm after time.

 

[morph]

Don't know why you would want to use something as big as 100x50 for a gate of 1.5M x 2M??? I'd use 40x40x3 and that would be plenty.

1 problem you'll have is they're slightly wider than a standard sheet of ply so a easier way would be to sheet them in 1.2mm Galv sheet as you would only need 2 1.5x3M sheets. Then you would only need a center rail in the frame and no bracing as the sheet would keep it square......