With minor variations, I have built a standard 1200mm x 1800mm domestic trailer with a solid frame of box section or rectangular hollow section (RHS) mild steel. The frame is braced by angle-iron cross members, and has a sturdy ply wooden deck. It’s best to use not less than five-ply 12mm minimum — in this case we have used seven-ply 17mm.
The tailgate and the front gate have the hinge pins all facing the same way, so the gates can be taken off when you want to open up the trailer for carting over-length timber, etc. Welding is the key to putting together the frame, and a cutting list of the lengths of steel is provided elsewhere in this article.
Steel RHS comes in eight-metre lengths and angle iron in six-metre lengths, so it will need to be cut to size. The principal trailer components — coupling, safety chain, mudguards, wheels, and so on, as outlined in the components list — can all be bought from regular trailer component suppliers. Full assembly instructions will come with those components.
An important first step
A crucial step in building the trailer is to get the axle stub straight, otherwise your tyres will chop up as they run. I use a jig of angle iron to get this straight, but I can show how to do it for a home workshop, simply by holding the axle stub firmly against the bottom and one side of the box section axle to ensure it is square. There must be good welds on the axle stub.
The plate where the coupling is bolted must be strongly welded to the drawbar for safety reasons when towing. If you have any doubt about your welding experience, have an expert do the coupling plate weld.
Clamps are a very important part of building the whole trailer — they are used every step of the way. It will speed up the assembly of the trailer if you pre-cut all material. I then mark all the pieces, especially with top, bottom and sides, and front and back.
While home workshop owners are exempt
