I have an old large chimney at my cabin. (Very large stones like an old building foundation.) It is need of some TLC, tuck pointing to be exact. My question is…..is there a good box store product for this? I want to make sure it is weather/water proof. I am sure there are mason’s that know of some complex mixtures….I am looking for a good DIY type of product. Something that will do the job but not too complex.