Removing concrete render - How Detailed?

[AeronC]

Good day Everyone,

I'm after some advice on the process of removing concrete render in preparation for applying lime render.
As you can see we have removed the majority of the thick concrete render that covered the entirety of these internal walls.

In places there are a few, extremely resilient/hard to remove, areas of concrete left.
My question is how vital will it prove to remove these last bits? As it's seems a great deal of work for what could possibly be a small reward.

The area that has been rebuilt with concrete blocks is obviously a concern but probably cannot be remedied without an amount of work we're not comfortable with taking on at this time, plan is to replace the blocks that have been removed unless anyone can offer a good alternative?

Any other advice is of course welcomed.

Many thanks!

 

[Glenn586]

Well done you have done a cracking Job. I declare those walls breathable.

 

[Stevers]

My basement chimney breast had been 'damp proofed' with a cementicious slurry, I wasn't able to reasonably get all of that off. The NHL render went on fine and has done an excellent job of drying it all out. As it was before, steel would rust just sitting on the stone mantelpiece, no such problem now!

There is moisture coming through, but it's at a level now that is not visible and in particular is not able to pull salts through which is what I think we're aiming for in making things 'breathable'.