Lime plaster or concrete plaster in an old house?

hoodie6029

Hi Folks,

My parents have an old cottage in the West that was renovated in the 90's. It's stone built and from the 19th century. It was falling down by the 90's and it was done up with a concrete floor poured, kitchen and bathroom extension added. One exterior wall was replaced with a modern block one.

The whole place was plastered inside and out in concrete plaster. The damp is really bad in the old walls of the house. Given the nature of old stone construction I'm guessing it would be impossible to add a damp proof course retrospectively?

Would changing the plaster to lime plaster on these old walls be better than the plaster? I vaguely remember hearing that lime plaster doesn't get as damp as quickly as concrete and is better suited to the old stone

TIA

Metric Tensor

A few pictures would make a massive difference. The "damp" might not be coming from where you think it is.

Lumen

The issue isn't that lime doesn't get damp as quickly, almost the opposite, it's that it allows moisture to move through the wall and dry out (both ways).

There's a "Cottageology" FB group with loads of examples of people rectifying this, often DIY. The stories are inspiring.

The usual recipe is French drains round the perimeter, pull off any cement plaster & render, redo with lime and insulated plaster (hemp, cork).

That's obvs a big job so in the meantime check the guttering, downpipes and existing drains and look for cracks in the render which may be allowing water to penetrate.

Plus as usual don't ignore ventilation.

Metric Tensor

Great post Lumen - it's what I was hinting at but too lazy to type!!

hoodie6029

Cheers for the replies.it sounds like a big job even on this small house. I'll let the folks know what lies ahead for them.
Such a pity the builder didn't do it when renovating but I suppose there was still that attitude of 'out with the old' even then.

bobbyy gee

lime plaster let's out water

https://ryedaleplasterers.co.uk/property-of-the-week-lime-work/

bobbyy gee

another renovation
https://www.heritage-house.org/case-histories-1/examples-of-our-work/stone-cottage-in-birmingham-.html