Painting a dank, damp, musty old outbuilding

[Scarletpimpofnel]

I've an old outbuilding that looks to me to be made of 1950's concrete blocks with no DPC. The walls are quite damp. I want to paint it so was thinking:

1 - Remove vegetation growing over/around it.
2 - Reroof and add guttering.

I was thinking of (1) adding a waterproof paint on the outside to stop rain penetrating the walls from the outside and (2) using a limewash paint inside to allow any damp in the walls to breathe out.

Does this sound a good plan, any better ideas?

Thanks.

[RGG]

No need for lime wash paint.

A "proper" emulsion paint has some breathing properties - used for bare / new plastered walls.

A vinyl matt, the usual emulsion, is less apt to breathe.

Use the first and you should be okay.

https://www.screwfix.com/p/fortress-trade-10ltr-br...

[MajorMantra]

Worth considering what's making it damp. Is it actually condensation rather than penetrating moisture? Would improved ventilation help?

It it is chronically damp and you want to reduce the tendency for mould to grow, making your own limewash is extremely cheap and easy.