After a bit of advice following a knock through... As you'd expect, there was a DPC atop those concrete blocks in my picture, now removed along with the wall. Next step is making good and I was planning to put a latex compound down to smooth/sort out slight level differences. BUT, without the DPC, I worry about the risk of moisture ingress via capillary action. It's a block and beam floor and those concrete blocks are ultimately in ground contact. What's the most practical way to resolve the risk?

https://www.toolstation.com/everbuild-black-jack-damp-proof-membrane/p10290?store=null&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gad_source=1&gad_campaignid=21016232523&gbraid=0AAAAAD-vLcX3SICQivfTjJrOYFQACEcF9&gclid=CjwKCAiA0eTJBhBaEiwA-Pa-hbx22hKHf4L0JhrXGpuqT5asuMzSUApyYANX_9hicTjUNIoDLEk_zBoCpeYQAvD_BwE

 

I'd chip away an inch or so from the top of those blocks, then apply the liquid DPC, and then after at least 2-3 coats have been applied you can back-fill with a self-levelling compound.

 

You can get 1L tins iirc.

thanks that's not a bad idea

54 minutes ago, JFH777 said:

thanks that's not a bad idea

Just make sure you foam or mastic any gaps either side of the blocks so the SLC doesn’t just disappear down south. 

I'm wondering if I might actually be wrong.... In trying to figure the situation out, I've been watching lots of videos about block and beam floors. In every case it seems that a DPC is placed underneath the beams themselves. So, I might be worrying about nothing. If that's the case though, I can't understand why there was  an additional DPC at screed level for the internal walls. This is the same height as the DPC visible on my exterior walls. Maybe a DPC was applied to the internal walls out of an abundance of caution? Am I talking rubbish?

Do as @Nickfromwales advised. We cant tell if that wall has been built off the B and B, or off the foundations. Spend £30 and have it sorted.

1 hour ago, JFH777 said:

I'm wondering if I might actually be wrong.... In trying to figure the situation out, I've been watching lots of videos about block and beam floors. In every case it seems that a DPC is placed underneath the beams themselves. So, I might be worrying about nothing. If that's the case though, I can't understand why there was  an additional DPC at screed level for the internal walls. This is the same height as the DPC visible on my exterior walls. Maybe a DPC was applied to the internal walls out of an abundance of caution? Am I talking rubbish?

Not many would take the risk of omitting the secondary (industry standard) line of defence; the DPC at floor level.

 

There are no guarantees with the subfloor DPM/DPC so it’s certainly not an abundance of caution, more a sensible, standard methodology which give you the obligatory belt, and accompanying braces

 

Do as the Welsh fella says, and you’ll live happily (and dry) ever after.

 

The end.