Heritage Lime Plaster
If you live in an older building you might want to think about lime plaster. Many old buildings have suffered renovations using gypsum based plasters and sand and cement renders. These products are fine in the right context, but their relative lack of porosity means that they can cause problems with moisture in older constructions. If you have persistent damp patches, or powdery white salt deposits, these are signs that moisture and salts are present. Removing the existing plaster/render and replacing it with lime might be a solution.
Old chimneys are particularly susceptible to these issues, as decades, or even centuries, of soot can create salt deposits that will work their way out and appear on and around the chimney breast.
An interesting approach is to use hemp in the base coats of lime. As well as having insulative properties, which can help with your heating bill, hemp can help with regulating moisture, and there is evidence that it also helps with salt deposits and soot issues around chimneys.
None of these materials are particularly expensive and may be the solution to ongoing problems in your house.