Old plaster removed, I need to plaster the substrate now, what process is the best?

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adelast

New Member
Hi everyone!

As some of you might know, I am renovating my small ensuite. Since the paint was peeling in some area and I didn't want to risk further issues after skimming over it, I started removing all the paint... what a job! I bought a paint stripper but it seems that steam is what actually helps to remove paint from the wall, anyway that's another story.
After removing the paint, I noticed that what I think is an old plaster, had more cracks than what the paint was showing. So, since my plan was to enlarge the cracks, put some filler, clean the walls and then skim, I decided that it would have been easier to remove the plaster entirely (I think that was plaster) and then plaster from scratch.

Once I removed the old "plaster" (?) I noticed that the cracks are on the substrate too (I am not sure how to call this layer so for now I'll call it this way) so my questions are mainly two:

1. Do I need to do something about it? Should I enlarge those and put some filler before plastering over?
2. This substrate is a bit dusty, should I clean it with a brush, apply 3 part of water and 1 of PVA before plastering over it? Or do I need to wash it with sugar soap?

This house is a bit over 60 years old, this small ensuite has been made out of a space that was once a builtin closet.


Many thanks!
window.jpg crackExample.jpg
 

Stewie03

Well-Known Member
All the lines on the plaster is a key for the finish coat to adhere to if the plaster is still solid and stuck to the wall leave it on
 

adelast

New Member
All the lines on the plaster is a key for the finish coat to adhere to if the plaster is still solid and stuck to the wall leave it on
Hi @Stewie03 , thank you for the first productive answer :)

Yes I don't mean to fill those, I was trying to reply to the first message and explain that I just removed the think coat with a simple scraper, and I am not trying to "let my house falls down".
This rough plaster is still solid and I don't plan to remove it, I am just wondering if I should do something for the small cracks that it has (like the one in the image with the purple rectangle) as I am worried that if I simply put on the finish coat it will crack again immediately.

Like I said, the house is 60 years old and there always be movement, I just would like to avoid having a crack in the finish coat again after few days.

@Retired Spread Thank you for your reply! May I ask what s&c stays for?

The area I need to plaster is 90cm x 230cm (there's also a small window in the middle), it's one wall in the smallest bathroom of the house and I believe is the perfect surface for my first attempt in plastering.
 

MakeItSmooth

Well-Known Member
May I ask what s&c stays for?

Sand & Cement


Before you even think about plastering that surface, make sure you understand how to prepare it properly, to control the suction, or you'll have cracks and crazing all over your new plaster.
 

adelast

New Member
Sand & Cement


Before you even think about plastering that surface, make sure you understand how to prepare it properly, to control the suction, or you'll have cracks and crazing all over your new plaster.
Hi @MakeItSmooth , thanks for your reply. Yes, all the info I got so far were suggesting to use 3:1 water and PVA but that was for walls that already had a smooth layer. This s&c (thanks!) is very dry and dusty so it looks like I need something more, perhaps I need to buy Thistle GypPrime. Any suggestions?
 

MakeItSmooth

Well-Known Member
Hi @MakeItSmooth , thanks for your reply. Yes, all the info I got so far were suggesting to use 3:1 water and PVA but that was for walls that already had a smooth layer. This s&c (thanks!) is very dry and dusty so it looks like I need something more, perhaps I need to buy Thistle GypPrime. Any suggestions?

Honestly?

I'm not taking the mick or being defeatist, but I think you'd be better paying a professional spread to do this particular job.

It's up to you, but that's my honest advice.
 

adelast

New Member
I have reached out to three professionals, one didn't show up, another refused the job on the phone as it was too small (again, it's only one wall 90cm large and 230cm tall) and the third told me that he would have accepted it only if he could plaster over the paint and that was definitely a no go as the wall had multiple paint layers and part of it was peeling. Also, when I removed the paint I saw some mould (very few small spots) I am not sure if they painted over it but anyway I was happy to haven't had someone plastering over that.

Anyway I appreciate your advice (and the way you shared) but for current situation I'd like to give it a go. I am not a plasterer and I don't want to be one, I just want to do some DIY in this very small room.
 

adelast

New Member
If someone has any other input, I was thinking of brushing this sand and cement with water, apply a layer of thistle bonding and then thistle multifinish. Any thoughts on that? :)
 
D

Deleted member 46546

Guest
If someone has any other input, I was thinking of brushing this sand and cement with water, apply a layer of thistle bonding and then thistle multifinish. Any thoughts on that? :)
Phone more plasterers until you get someone happy to do it that you trust to do a good job. Its a days work to sort out and look spot on. You will 100% f**k that up.

"I believe is the perfect surface for my first attempt in plastering." you're wrong

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S

Slothai

Guest
If someone has any other input, I was thinking of brushing this sand and cement with water, apply a layer of thistle bonding and then thistle multifinish. Any thoughts on that? :)
Remove any loose material. PVA it a couple of times. Bonding then multi.
 

adelast

New Member
window-jpg.65758




You'd use bonding on an external wall, that's also in a bathroom?


Are you referring to the Angle bead area? If so, before there was simply multi finish...anyway that's not exactly the external wall, the external wall is made of very small small stones... I am not sure how that's called sorry, I am not an English native speaker nor from UK
 
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adelast

New Member
Remove any loose material. PVA it a couple of times. Bonding then multi.
Thank you for your reply @Slothai , this is what I was thinking of, and I am glad someone is giving real suggestions.

I am not sure why in a DIY forum just a few people gives real DIY tips... I understand that if I do that and it's my first site plastering attempt, the surface won't be entirely smooth, there might be some extra fat, I might be losing 50 quid, etc. But while I appreciate the suggestion of having a professional doing the job, I am here in a DIY forum to double check the steps that should be done in this phase.

My questions were mainly due to the dusty surface of the (what I found out to be called) sand and cement, as I wasn't sure if I had to wash it or putting just PVA.
From what I understand, brushing that surface and apply 3:1 water+PVA will be enough and actually some dust might help with the bonding (but not if that's too much).
I didn't think about applying bonding plaster first, as while the surface isn't flat at all I thought that the multi-finish could just work, but I realise now that in some spot we are taking about 7-8 mm so putting bonding first makes sense and that's a good suggestion.

I am sorry for such long message, but I really don't get why most of people here seems so bitter and refrain to give proper advice. I am posting in the DIY section, no-one is going to steal your job ¯\_(ツ)_/¯
 
D

Deleted member 46546

Guest
Thank you for your reply @Slothai , this is what I was thinking of, and I am glad someone is giving real suggestions.

I am not sure why in a DIY forum just a few people gives real DIY tips... I understand that if I do that and it's my first site plastering attempt, the surface won't be entirely smooth, there might be some extra fat, I might be losing 50 quid, etc. But while I appreciate the suggestion of having a professional doing the job, I am here in a DIY forum to double check the steps that should be done in this phase.

My questions were mainly due to the dusty surface of the (what I found out to be called) sand and cement, as I wasn't sure if I had to wash it or putting just PVA.
From what I understand, brushing that surface and apply 3:1 water+PVA will be enough and actually some dust might help with the bonding (but not if that's too much).
I didn't think about applying bonding plaster first, as while the surface isn't flat at all I thought that the multi-finish could just work, but I realise now that in some spot we are taking about 7-8 mm so putting bonding first makes sense and that's a good suggestion.

I am sorry for such long message, but I really don't get why most of people here seems so bitter and refrain to give proper advice. I am posting in the DIY section, no-one is going to steal your job ¯\_(ツ)_/¯
Because it isn't a DIY job...

Putting some shelves up is DIY. You're talking about doing a job you aren't in the slightest bit capable of doing. The best advice you got on this thread was, "don't do it"

Its like me asking on a mechanic forum, "any tips on changing my head gasket? I have no experience but was thinking of wacking it with a hammer then blowtorching the new one on"
 

Pwl

New Member
Hi
First plaster won’t stick to a dusty surface so PVA or blue grit would be a safe bet before any plaster is applied……
Secondly if the sand /cement is solid leave it in place…..
Third I’d try to scrape of the old skim coat/paint leaving the backing coat in place then I’d bead up the areas that need beading and pre fill them with sand/cement or a backing coat then I’d fill any holes missing bits etc then unibond and skim……
Personally I wouldn’t create any unnecessary work and if the original backing coat is solid leave it in place…….
I’d avoid bonding it then skimming as it’s just another layer and potential problem.
Don’t overthink it keep things simple.
Hope this helps
 

adelast

New Member
Because it isn't a DIY job...

Putting some shelves up is DIY. You're talking about doing a job you aren't in the slightest bit capable of doing. The best advice you got on this thread was, "don't do it"

Its like me asking on a mechanic forum, "any tips on changing my head gasket? I have no experience but was thinking of wacking it with a hammer then blowtorching the new one on"
Thank you for your input here @Nath80 .
Thing is that the surface is less than 2.5sqm, it's one wall of the smallest en-suite of the house (my own house) in a guest room. I could take three months and take my time doing that, it really wouldn't matter to me. I already have all the tools, worst case scenario I would need to make more calls to find a professional and lose £20 of materials. I get your point, I understand that this might cost me few hours of work, some £ for the wasted materials and I might need expert help anyway as this might turn in a disaster. But once I accepted these terms, at the end of the day it would be nice to have some practical tip :)

Thanks again for your input, you still took the time to reply to my message so you deserve a (y) anyway
 

adelast

New Member
Hi
First plaster won’t stick to a dusty surface so PVA or blue grit would be a safe bet before any plaster is applied……
Secondly if the sand /cement is solid leave it in place…..
Third I’d try to scrape of the old skim coat/paint leaving the backing coat in place then I’d bead up the areas that need beading and pre fill them with sand/cement or a backing coat then I’d fill any holes missing bits etc then unibond and skim……
Personally I wouldn’t create any unnecessary work and if the original backing coat is solid leave it in place…….
I’d avoid bonding it then skimming as it’s just another layer and potential problem.
Don’t overthink it keep things simple.
Hope this helps
Thank you for your reply @Pwl, the sand and cement seems solid, I think that originally cracked (very thin cracks) due to the fact that it dried too fast, at least that's my guess. Do you advise against putting bonding and then skimming even if I make the bonding layer very thin?
If so, what would you recommend to fill any holes?

Many thanks!
 

Pwl

New Member
Thank you for your reply @Pwl, the sand and cement seems solid, I think that originally cracked (very thin cracks) due to the fact that it dried too fast, at least that's my guess. Do you advise against putting bonding and then skimming even if I make the bonding layer very thin?
If so, what would you recommend to fill any holes?

Many thanks!
I’d just fill the holes etc get yourself a bag of bonding…..
I wouldn’t put a thin layer of bonding on if I didn’t need to
 

adelast

New Member
I’d just fill the holes etc get yourself a bag of bonding…..
I wouldn’t put a thin layer of bonding on if I didn’t need to
Gotcha, thank you! I gave it another look and yes, the surface doesn't seems so in bad shape that needs a new layer of boding. I will definitely fill the holes, cover in PVA and then go with multi finish.
Many thanks for your help!
 
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Spudknit

Well-Known Member
You'll piss that..put pics up when you've done,don't listen to these cowboys there havnt got a scooby doo..Good luck :coffe:
 

Lastlaff

Well-Known Member
Get a spread in - this small job needs years of experience to do correctly. Do you even know how to knock-up gear? Dust, suction, Bonding (feckin no btw), PVA ratio, beading etc etc. Get a spread in and enjoy watching a pro…you’ll feel better and realize plastering is an art and not just a trade. In your fourth post you mentioned ‘mound’, and you think Bonding is appropriate…no!
 
S

Slothai

Guest
window-jpg.65758




You'd use bonding on an external wall, that's also in a bathroom?


Yes and yes.

Bottom line is ... He's going to do it anyway, its less than 2m2, if it goes wrong then he's learnt his lesson. If it doesn't and he's happy with it then job done.

I don't generally reply as I know how unknowns and DIY'ers get mauled by the plastering forum elite, but cmon its a DIY section, he wants to give it a go.
 

Monkey Boy

Well-Known Member
There ain’t a DIY section it is all just one forum
All those categories are a waste of time - the reality of a forum is it all just boils down to a thread title that’s all
 

Cockney1

Well-Known Member
Why is Plastering even considered as DIY? Are electrics and plumbing also classed as DIY??
Asking for a friend............
 

andrwclem

Active Member
Give it a go!
What’s the worst that can happen?
Yes and yes.

Bottom line is ... He's going to do it anyway, its less than 2m2, if it goes wrong then he's learnt his lesson. If it doesn't and he's happy with it then job done.

I don't generally reply as I know how unknowns and DIY'ers get mauled by the plastering forum elite, but cmon its a DIY section, he wants to give it a go.
Thank you for your reply @Pwl, the sand and cement seems solid, I think that originally cracked (very thin cracks) due to the fact that it dried too fast, at least that's my guess. Do you advise against putting bonding and then skimming even if I make the bonding layer very thin?
If so, what would you recommend to fill any holes?

Many thanks!
Consider dot and dabbing plaster board if it isn't a wet room
 

leefaithfull

Well-Known Member
Hi everyone!

As some of you might know, I am renovating my small ensuite. Since the paint was peeling in some area and I didn't want to risk further issues after skimming over it, I started removing all the paint... what a job! I bought a paint stripper but it seems that steam is what actually helps to remove paint from the wall, anyway that's another story.
After removing the paint, I noticed that what I think is an old plaster, had more cracks than what the paint was showing. So, since my plan was to enlarge the cracks, put some filler, clean the walls and then skim, I decided that it would have been easier to remove the plaster entirely (I think that was plaster) and then plaster from scratch.

Once I removed the old "plaster" (?) I noticed that the cracks are on the substrate too (I am not sure how to call this layer so for now I'll call it this way) so my questions are mainly two:

1. Do I need to do something about it? Should I enlarge those and put some filler before plastering over?
2. This substrate is a bit dusty, should I clean it with a brush, apply 3 part of water and 1 of PVA before plastering over it? Or do I need to wash it with sugar soap?

This house is a bit over 60 years old, this small ensuite has been made out of a space that was once a builtin closet.


Many thanks!
View attachment 65758 View attachment 65759
View attachment 65757
dont bother asking these clowns mush honest,,,
 
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