We fitted a spring based rubber seal on the front of the door that lifts when you open it. Bit like this https://shop.stormflame.com/automatic-threshold-seal-rp60-412-p.asp?gclid=EAIaIQobChMIuZ_uxM-J4AIVjLTtCh15SAjUEAQYBCABEgIX4vD_BwE
Works quite well. We tried brushes and so on - but it...