So what does cause plaster to fail in old houses i

Aubrey_Thicket

Hi all

This post is connected to a post I recently posted on here about damp courses. After a lot of reading and research I have discovered the great Damp Course Scam. So, whilst I write please allow me to ask you guys in the knowledge some questions regarding failing plaster.

I have previously renovated 5 old terraced houses (all in the same area and all built around 1920 - 1930). Houses that have outside toilets still connected etc. They all had the original plaster on the walls from when they were built. What I noticed in all of them is that the plaster on the walls seems to come off very easily. I'm talking easy as in you can get a paint scraper behind it and pull large chunks of plaster away, which is very helpful in total renovation. Sometimes the now removed plaster is also very sandy too. Of course, I'm certain that the plaster has clearly perished over the years just like any product approaching 100 years old and I don't have any issues with that. However, I just want to know a few things...

1. Is it normal in these old houses for the plaster to perish like this and come away from the wall so easily?
2. Why does it do this? Has the plaster literally died? Is it actually plaster?

Thanks all

Doozergirl

It is just age that causes it to go. Movement in the house causing cracks, general deterioration of the plaster product and bonding, contraction and expansion of the walls with heat and cold. The walls and the plaster are not the same product. They behave differently and I guess it makes sense that they eventually separate.

It is perfectly normal and expected, hence it even falls off internal walls which would never suffer from damp. I have never really thought about it in depth, I just know that it is normal.

If it does not fall off and the house is 100 odd years old, it is only because someone got there and replaced it before you.

sevenhills

Most of my plastered walls in my 1960s is ok, there has been a dry dusty patch, which all came off, which I just filled and then papered over the top.

FreeBear

Doozergirl wrote: »

It is just age that causes it to go. Movement in the house causing cracks, general deterioration of the plaster product and bonding, contraction and expansion of the walls with heat and cold.

I suspect that the lime in old plaster is also being leached out over time. I've got a few patches of lime plaster that is very friable and coming away from the walls. Seems to be limited to the external walls that are more prone to condensation. Most of the problem areas I've skimmed over with a mix of lime putty and finely ground marble & chalk - Well worth having a tub mixed up as it won't harden until it is applied to a wall.