Hi
I have a house which has cob/masonry walls. The builder used gypsum plaster. Within weeks there was a 'tide line' where hygroscopic salts were attracting water. I got them to remove all plaster off up to a metre high (as I was advised to do by an independent damp expert):
Ive had 2 lime plasterer come out. One said he could feather the lime plaster into the existing gypsum plaster and it shouldnt show that much. The other plasterer said that he wouldnt feather the lime plaster into the gypsum plaster becuase it would crack where the gypsum met the lime because the gypsum is cementious whereas the lime expands/contracts.
I thought I would get your opinions. (This forum has proved very helpful in the past!). Is it guaranteed to crack (as the plasterer said)? Is this likely to happen over many years, or after - say 2 years?
Also, as a follow-up question: How does lime plaster react with hygroscopic salts? Am I likely to get the tide line again?
Thanks
I have a house which has cob/masonry walls. The builder used gypsum plaster. Within weeks there was a 'tide line' where hygroscopic salts were attracting water. I got them to remove all plaster off up to a metre high (as I was advised to do by an independent damp expert):
Ive had 2 lime plasterer come out. One said he could feather the lime plaster into the existing gypsum plaster and it shouldnt show that much. The other plasterer said that he wouldnt feather the lime plaster into the gypsum plaster becuase it would crack where the gypsum met the lime because the gypsum is cementious whereas the lime expands/contracts.
I thought I would get your opinions. (This forum has proved very helpful in the past!). Is it guaranteed to crack (as the plasterer said)? Is this likely to happen over many years, or after - say 2 years?
Also, as a follow-up question: How does lime plaster react with hygroscopic salts? Am I likely to get the tide line again?
Thanks