jinkazama

Hi, We have a 45m square area that was insulated with 100mm celotex, wet underfloor heating, concrete and then the screed base. I asked our builder why there was no expansion gap and he said that they don't normally put them unless the room spans 10m or more, I've read that anything over 40m square and 8m in length should and we meet both those criteria. I then entered the house and found he had gone down with an angle grinder 10mm into the screed and created a crack as you can see and every 50cm or so put a perpendicular section of small metal rod ? He said the crack would then be filled with roof resin topcoat as we have some leftover. Surely expansion gaps have to be all the way down otherwise they are not expansion gaps and surely if putting them in you put them in first, the floor where the cracks are were laid at seperate times due to covid we could onyl get 6 tonne deliveries at a time so he's put the top crack where the sections were laid. Has anyone got a clue what he has done here and more to the point, if these cracks are of no use then surely the original problem remains, we have a large screed floor which has no expansion gaps.