old houses do not work very well with new materials as most of these are none breathable, your house would have been built using lime mortar, it would have had lime plaster, finished with a lime wash, all these materials allow the house to breathe and prevent dampness, cement/render/painting doesn't allow the house to breathe and creates dampness.double glazing can create condensation problems by sealing the house up and stopping ventilating open the windows a little and allow the house to breathe, the fact your mortar is crumbling may mean its the original lime mortar, this is good, their is no cement or additives in lime mortar it is N.H.L
重新点名可能大有帮助 提供自然液压石灰而不是水化石灰或水泥物料仍然可用,尽管比现代物料贵, 找能正确使用物料的人或多或多或少难以查找
个人会寻找使用原创素养恢复老化属性的特长
好运亚历克斯