ᐅ How do I seal the gap beneath a fire door?

Hello everyone, what is the best way to fill this gap? The gap is about 1.5 to 2 cm (0.6 to 0.8 inches) high. It is located under our fire protection door, at the transition between the utility room and the garage. When I step on the track, there is naturally some movement. Bugs and dirt always accumulate in this gap. I want to stop that now. At first, I thought about using silicone. But the gap is quite large. Then I considered using compressible foam tape. However, I don’t find that sufficiently sealed against bugs.

I would fill it with mortar, possibly paint it white afterwards. A leftover lime-cement plaster would also work.

Tx-25 schrieb:

Of course there is movement when I step on the track. Creatures and dirt always accumulate in that joint.

That is not normal. If there is movement there, the frame wasn’t installed correctly. Also, the area wasn’t plastered before the garage floor was paved. 🤨

Is it possible to put mineral wool insulation in there? It provides additional insulation (thermal bridge), and then apply colored silicone over it, which can also compensate for some movement.