Concreting hole behind drain to stop cavity wall access

[jackpot]

Got a rat visiting the cavity walls of the house. Pest control just been out and identified their most probable access point.

Question is, what is the best way to block up hole with some sand/cement

I've took up a small portion of rotten decking which is due to be ripped up at some stage anyway. I can see two
burrows assuming that have been made to access the hole. See pictures below.

The hole to be filled is somewhat behind the drain so access is not great.

How do I get the sand cement down this small strip or is there a better way?
I just stacked the decking cutoffs around the perimeter to hopefully stop access tonight as it's getting dark to start cementing.


Thanks

 

[jackpot]

Just a thought, would pouring down a dry mix like post crete work and then adding some water. Behind the drain and around the perimeter.

 

[kingandy2nd]

Post create aggregate might be too large to get down the gap.

I'd use a finger trowel personally, but any trowel and a wet mix would do. I'd use quick drying cement too

 

[HERTS P&D]

Chicken wire with foam filler.

Andy