Damp render on internal retaining wall

[Ullapete]

Old house renovation project - I am gradually replacing modern plaster and render with lime plaster and renewing decaying lime plaster.

In the kitchen there is an area of wall that is below the soil level of my neighbour's garden. The external wall is brick but the inside is rendered with a conventional sand / cement mix.

The wall was covered with ceramic tiles on top of the render and there was some evidence of damp on the render when I removed the tiles. However, this has been covered for years and its not really that bad all things considered. The skim came off with the tiles. Alternatives:

1) I could use something like a newton membrane and plaster on top but that could trap moisture in the wall?
2) I could remove the existing render and put lime plaster over the top - I'd prefer not too, as the existing render is mostly in good condition.
3) Simply apply lime plaster over the top of the existing render.

Any suggestions appreciated.

 

[tony1851]

If it's not too bad, why not just leave things as they are, albeit perhaps with new tiling?

As it's an old house with a floor lower than the neighbour's garden, some degree of damp would have been inevitable, though originally it may have dried off quicker with coal fires and natural ventilation.

You risk making the condition worse if you start altering things.