I have built a frame for the greenhouse in 45x195 mm pressure-treated wood. All pieces/sides are equally long +/- 1 mm, but there is still a 2.5 cm difference in the diagonals. It's not easy to try to "press it" as there are sturdy corner brackets. How much difference can be considered acceptable? It shouldn't be too off, or there will be issues fitting the greenhouse.
if the angle irons are vertical, i.e., not resting on the beam, then you can surely press them to make it exact. If they are resting on the beam, then it is probably more difficult. Based on my assumption that you have standing 45x95 beams with angle irons "inside" the corners. Just a certain amount of force is needed. Better to fix it before you assemble the greenhouse. Otherwise, you may need to loosen some screws.
Yes, that's correct, standing 45x195 mm with heavy-duty reinforced angle brackets in the inner corners. I cast a post base this evening to get some support and can try loosening a few screws to see if it goes easier.
