Can this former be trimmed.
Yes, that's one of feature of those trays. You can use a handsaw to trim them down to size or to avoid obstacles such as uneven walls or corners.
900 x 900 mm tray can be shorten down to a minimum size of 760 x 760, although if you wanted to trim it to be smaller than 800 x 800, then I would recommend to go for 800 x 800 mm wet room tray instead, as it's also one of our standard size.
If you wanted to avoid obstacles it's fine to cut only from one side, however if you wanted to shorten it down to let's say 850 x 850, you should take 25 mm from each side, so pre-machined slopes towards the drain are preserved.
Please notice that we can also supply custom sizes. Let us know what's your shower area and we will reply with the best solution for yourself.
I am happy to assist if you have any further questions.
David 020 7193 0953