Just found out the house we are buying has been painted with Sandtex on top of lime mortar. I'm assuming this is very bad (despite the Sandtex website saying it is breathable AND waterproof). I find it odd they understood about lime mortar and then coated it in Sandtex. Am I wrong to be worried and think we would need to get it off? (I dont think I am - and it's going to cost a bit to get it off I assume - good £3-5K?)