Musty smell behind dishwasher

[tim120000]

hello
we have a musty smell behind dish washer when its raining. its a 70s semi (ex council ) stone walls no insulation . new kitchen put in by past owner a few years ago what is the best course of action?
we did bring a damp guy a we had a wet wall in the hallway and he diagnosed condensation went away with dehumidifier.
attached a photo behind dishwasher. I don't know how to fix the unsightly mess of cables/wires/pipes
friend suggested coating entire outside of the house with water seal?

 

[foxhole]

Probably have one or more leaks, may be just cold water supply swetting making things damp and must . Damp in hall suggests property has poor ventilation.

 

[JP_]

Suspended wooden floors, or concrete?
If it only happens when it rains, I would assume that the problem is not pipes leaking.
But, if already a musty smell, then rot is probably in there, somewhere, so really needs cleaning out.
Loads of mould killer, then treatment on all wood.

 

[Nige F]

As Jonbey says + is there a standpipe with a trap on dishwasher waste? Wouldn't hurt to run the machine with a cleaner bottle in it.... 70's build must have a cavity wall even with stone outside