Retaining wall for garden room - worried

[Sandwellcome]

Hi guys
Very new to this but wanted some opinions and answers. Long story short, building a garden room.
Concrete base poured 200mm, floating with dpm and a142 reinforced.
Built a retaining on top to hold back next doors field. The field slopes away from our boundary is about 1m high, we’ve installed a french drain and back filled with gravel. The wall is 5.5m long. Pics attached.
The retaining wall is black jacked, and going to be used as the the wall for the room. Concrete wall has been built round, but no DPC has been installed by the builder. Timber frame is going on top. what can I do to counter act no dpc on the brick course? Should I also black jack that whole back wall on the inside?

 

[23vc]

You need a proper vertical dpm, and/or a cavity, as well as drainage considerations give it’s retaining a substantial amount, I personally deffo wouldn’t just rely on blackjack for this but depends how it was designed.
Not sure how the Timber frame on top is detailed but make sure you’re avoiding a cold bridge through the retaining blockwork.

Personally I’d look at doing a proper retaining wall with drainage, then a gap, then build your garden room totally separate to it say a foot back… could be way less painful

 

[mrrusty]

Absolutely agree with @23vc - build your timber frame away from the wall with a maintenance gap. You'll avoid a world of pain should that retaining wall leak water through as it well might, and the timber frame will have all the nice insulation in. The gap gives you space for any overhang/gutter to stop the water running down the back wall.