Material size?

[Robotstar5]

25 x 25 or 30 x 30 erw would be more than adequate for that job, I've made quite a few over the years for similar lightweight trailers, its dead cheap, nice and light, and easy to work with,
You could build the 2 side frames then bolt in 4 cross bars for the roof in line with the vertical members, it then knocks down easily for storage when you want to take it off.

Thanks for the suggestion Paul, just looked it up and it's 1.5mm wall thickness, is that the right one?

I don't really need to dismantle it, as should I ever remove it, there is plenty of room at the stables to store it and having it in sections may make it hard to keep watertight.

 

[Robotstar5]

No need for birdsmouthing, just copy landrover tilt hoops and squash the tube ends flat and drill for bolts.

I'd forgotten about the LR technique, it would be OK if I fitted a "ragtop" cover, but I may struggle riveting the Al sheet on neatly?.

 

[Paul.]

Thanks for the suggestion Paul, just looked it up and it's 1.5mm wall thickness, is that the right one?

I don't really need to dismantle it, as should I ever remove it, there is plenty of room at the stables to store it and having it in sections may make it hard to keep watertight.

You can get it in 1.5 and 2mm, either would do, it comes in 6 mtr lengths,
The last one I made was for a 6' x 3' trailer, stood about 3' above the existing sides and was infilled with 2" weldmesh, used for transporting scrap card to recycling, plates on the legs to fix through the trailer sides.
Here's the rough sketch I did at the time to show the customer what he would be getting for his money.

 

[Robotstar5]

Provisional cutting list works out to 36 metres so I will order 7 lengths, then there will be lots of measuring and marking shame there isn't a "nesting" program to input all the sizes needed to give a cutting plan.

 

[WorkshopChris]

http://cutitfor.me/
http://www.mig-welding.co.uk/forum/threads/online-cut-list-calculator.75097/page-3

 

[penfold]

Well now you know one that hasn't , you're right the main hoops would look nice out of tube, but then I would have to "birdsmouth" a load of tubes to weld in for support.

I'd forgotten about the LR technique, it would be OK if I fitted a "ragtop" cover, but I may struggle riveting the Al sheet on neatly?.

Pipe clips?

 

[Robotstar5]

http://cutitfor.me/
http://www.mig-welding.co.uk/forum/threads/online-cut-list-calculator.75097/page-3

Thanks for link, I've left the cutting list at work so will have to give a go in the week.

 

[bigegg]

I saw a trailer someone had put a truckman top on which gave me the idea. I'm a bit limited on metalworking resources but plan to PU/Sikaflex and rivet the sheets on, will overlap the top and front to keep out water.

Truckman tops to fit a certain age of nissan navara are practically valueless - my next door neighbour has one in his garden he couldn't get a tenner for.