How do I know if fire stopping was done properly?

Go and look at one pipe. Say a 110mm plastic waste pipe through a block wall in a riser.

We start with the collar. It should be a metal ring screwed to the wall face with the intumescent liner touching the pipe, and every screw biting into blockwork and not only the plasterboard lining. Then the gap between pipe and block, which should be full of mortar or mastic. If all you see is a ring of grey foam, it hasn't been done.

Then go round to the other face of the wall. The data sheet may call for a collar on both. People miss the second one all the time.

A tray is a different story. Batt should be packed tight in the opening, faces coated, with a label naming the product. Then look at the cables on the edge. When somebody's pushed a new data cable through next to the tray you can shine a torch in and see the light on the other side.

Now ask for the record. One line per seal, something like 3.14, second floor riser, 110mm waste, collar both faces, mortar fill, photos 3.14a and 3.14b.

Last, count. If the survey found 60 gaps and the record has 52 lines, eight went missing from the wall or the paperwork.