Removing plaster in old house (and reviving stonework)

[Oxbow16]

Hi all

 

I'm making a start on removing the thick plaster, etc on the internal walls of the old part of my house.  I can't be certain, but I think it would have been applied in the mid-1970s.  It's really thick in places - up to 50mm/2 inches.  I'm hoping to clean the stonework up afterwards and re-point (with lime) if needed.  Prefer the natural look, and love the history of the place.  Prefer a cold bedroom too before anyone mentions insulation ;)  

 

While working the hammer and chisel, questions have been coming up in my head...

 

-  I'm curious as to why the "scratch coat" (is that the right term?) would have been put on so thick? 

-  Can anyone tell whether it is basic sand and cement or something else? 

-  Might it have had some kind of damp proofing element? 

-  Are there any downsides to removing it (I appreciate something will need to be done where the ceiling meets the wall)? 

-  Any tips on how to clean up the front of the stonework easily?  At the moment I'm just using a wire brush, but hoping for a less labour intensive and more effective solution!  

 

Any comments most appreciated.

 

Cheers

 

 

 

 

 

  

[markc]

Does it look like sand+cement? any fibrous looking material in it? feels lighter than it looks? 60`s/70`s plaster, especially applied in thick layers could contain asbestos 

[Oxbow16]

Thanks for the quick reply.  

 

Tbh, I'm not certain.  The thin front layer is pinkish, and the thick backing is grey.  To my untrained eye is seems like sand/cement with thin plaster finish.  There's no fibrous material and I wouldn't say it is lighter than it looks.  The sack fulls I've been removing are plenty heavy enough   

 

We had quite a lot of things tested for asbestos when we moved in, but the walls weren't one of them.  If memory serves, I think I looked into it at the time and was told it was not worth testing.  

 

I've adding some photos showing a close up of the plaster/ and sand/cement(?).  I've done some with the flash on and some with it off.  

 

Thanks again

 

 

 

 

 

 

 

[markc]

looks ok to me, and you are obviously well aware of asbestos. As you say, looks like mortar as the scratch coat ... albeit rather thick, with plaster skim on top.

Wire brushing is the easiest way to clean up the stone, failing that its sandblasting r compressor and needle gun.

[Oxbow16]

Thanks @markc

 

Yep, I'm aware of asbestos and had a lot tested for it, but clued up might be pushing it!  

 

It seems there are two layers of the mortar, which shows up in the middle photo rather well cos of the flash.  So I'm thinking it was base coat of mortar, second coat (scratch coat), followed by the plaster skim as you suggest.  

 

Sandblasting I think would be a bit on the heavy duty side and I'd prefer to DIY it if I can.  Will look into compressor/needle gun.  What about one of those wire brush things attached to a drill?  Could that be effective or too abrasive?  

 

More generally, could removing it cause any problems?  Sorry for the potentially stupid question, but could there be anything structural about it seeing as it is so thick?  The floor joists go into that wall, and they're already undersized.  Could removing it (will be doing the same in the room below) weaken the joists by removing an inch or two of support?  

 

Thanks a million.    

[markc]

No such thing as a stupid question, wire brush on a drill would be much easier than hand. 
removing the plaster/render won’t affect anything structurally, if the mortar is falling out from the joints just re-point the stonework to stabilise.

[Oxbow16]

Thanks @markc

 

A few folk on another forum seemed to think I should be more hesitant and think twice about removing the render.  But I've since had someone come round to take a look...  He said he thought all looked well, that I should continue, and that removing concrete render and re pointing in lime was a good thing for the fabric of the building.   

 

I think I'll therefore continue, but any other thoughts in the meantime from forum members are welcome.

 

Have a great weekend everyone.

[Cpd]

2 hours ago, Oxbow16 said:

But I've since had someone come round to take a look...  He said he thought all looked well, that I should continue, and that removing concrete render and re pointing in lime was a good thing for the fabric of the building

Absolutely right

 

i would use a wire brush on a small grinder, much easier to control and more efficient. 
needle guns are GREAT but you need a decent compressor to run them effectively.

 

On 13/07/2021 at 14:06, Oxbow16 said:

I'm hoping to clean the stonework up afterwards and re-point (with lime) if needed.  Prefer the natural look, and love the history of the place.  Prefer a cold bedroom too before anyone mentions insulation

 

I am at this point right now, I have a cottage that I am going to convert for my parents, it’s always had exposed stone walls but I am looking at insulating them all……. I will have the conversation with them but I just don’t like the idea of huge cold bridges sucking out the heat….. I repointed them so carefully years ago and it’s going to be a shame to loose the “look” but great to see my electric bill go down ! 
 

i like to really show the stone of when pointing and brush back the mortar, I prefer to paint it afterwards as I don’t like the natural look ! 
 

 

Edited July 17, 2021 by Cpd