patching plaster

[plasticpigeon]

Hello all. I am planning to try and get the plaster in my front room sorted out between Christmas and new year. I am going to try and save the majority of it, but some is falling off, particularly around the bay window and the door, so I will have to take it back to solid stuff in some sections. The room is dry and has a suspended floor, so I am not so bothered about using lime as I was in the solid floored kitchen which has a dividing wall built off the ground with no dpc. I was looking at using browning to patch in but realised it was £9/bag! So now I am looking at sand lime as per original, or weak sand cement or sand/lime/cement, which I am tempted by as it is easier and i will be able to get it finished more quickly. Are there any other alternatives I should consider?

 

[Roger H]

Hi Plasticpigeon. There will be others far more expert than me but I (total novice plasterer) had success with hydrated lime and paving sand (fine and sharp). Scratch coat was 3:1 and increased ratio to 1:1 for skim. Carbonated perfectly over a week and feels dead sound.

You can buy pre-mixed top coats with lime putty and extra fine aggregate but I was going for cheap and simple.

 

[Penners]

PP - you'll get the best results if you try to duplicate the material that's already been used. A patch of gypsum plaster in a wall of lime plaster will almost certainly tend to develop hairline cracks around it on a fairly regular basis, due to differential expansion and contraction.

 

[plasticpigeon]

PP - you'll get the best results if you try to duplicate the material that's already been used. A patch of gypsum plaster in a wall of lime plaster will almost certainly tend to develop hairline cracks around it on a fairly regular basis, due to differential expansion and contraction.

Hi Penners, the plaster in my house is a bit odd. It is definitely a very weak lime mic for the render, and then the top coat or set coat or whatever it was traditionally called is lime based with fine reddish sand, but must also have gypsum in it, as it is quite hard, much harder than what is underneath. I think they gauged witrh gypsum in those days so perhaps that is what it is.

 

[skier-hughes]

Our old lime plaster is rock hard, much more so than the new lime plaster that is between 2 and 7 years old!