Large canvases, when stretched, can twist and distort making them hang badly and not lie flat against the wall, with one or more corners sticking out.
Most framers will insist that they need framing with an outer frame to hold them flat.
At inspirations, we use strong stretcher bars and incorporate bracing bars from top to bottom as well as from side to side. These bars need to be fixed to the outer bars with specialist brace bar sockets and the braces cut with cross halving joints where they cross over.
The result is a stretched canvas that will lie flat against a wall without the need for an outer frame.
As you can see, the canvas in the image is larger than Colin (you can only tell that it is Colin holding the canvas by his shoes!) in fact it measures 1.7 meters by 1.4 meters.