Building the attached run
This is the original metric version of the plan (millimetres/centimetres). See also Chicken coop plans: Imperial (feet/inches).
The run provides a place for your chickens to spend time outdoors in a safe environment. They can scratch around and exhibit other natural behavior, and because this coop is on wheels you will be able to provide them with a fresh patch of grass or soil every so often.
You may want to add some extra bracing in the corners, but the run is reasonably solid without further bracing. It is important to make sure the frame is square. Use a spirit level and/or a large set square to check the shape.
It is easiest to attach the four 860mm lengths of 50mm by 50mm timber first. Then attach the 800mm lengths on top and go from there. Remember to use both nails and adhesive for a good strong bond.