Sand cement render on top of existing plaster

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BigMacks

Member
I have a bowed solid exterior wall that needs levelling out upstairs in bedroom in my Victorian propety so I believe no cavity wall. By most it is out of level by about an inch in middle.

Wall was already plastered with multi finish and bonding applied in some places on top of original lime plaster nearly 20 years ago. Lime plaster underneath is not in such a great condition as you can imagine given the age of property.

I am not really concerned about damp as externally the wall is rendered and had it checked by a damp professional who said the wall is...bone dry (his exact words) after he checked with his machine. Just the usual mould and condensation problems.

Have been advised to use sand cement render with added waterproofer on this wall to level out. Regular BG bonding is fine on other walls. Question is can I sand cement render on top of the exisiting multi finish plaster after giving it a good key and seal with pva?
 

Rossi46

Private Member
I have a bowed solid exterior wall that needs levelling out upstairs in bedroom in my Victorian propety so I believe no cavity wall. By most it is out of level by about an inch in middle.

Wall was already plastered with multi finish and bonding applied in some places on top of original lime plaster nearly 20 years ago. Lime plaster underneath is not in such a great condition as you can imagine given the age of property.

I am not really concerned about damp as externally the wall is rendered and had it checked by a damp professional who said the wall is...bone dry (his exact words) after he checked with his machine. Just the usual mould and condensation problems.

Have been advised to use sand cement render with added waterproofer on this wall to level out. Regular BG bonding is fine on other walls. Question is can I sand cement render on top of the exisiting multi finish plaster after giving it a good key and seal with pva?
No, it’s too strong and too heavy.
 

ChrispyUK

Well-Known Member
I have a bowed solid exterior wall that needs levelling out upstairs in bedroom in my Victorian propety so I believe no cavity wall. By most it is out of level by about an inch in middle.

Wall was already plastered with multi finish and bonding applied in some places on top of original lime plaster nearly 20 years ago. Lime plaster underneath is not in such a great condition as you can imagine given the age of property.

I am not really concerned about damp as externally the wall is rendered and had it checked by a damp professional who said the wall is...bone dry (his exact words) after he checked with his machine. Just the usual mould and condensation problems.

Have been advised to use sand cement render with added waterproofer on this wall to level out. Regular BG bonding is fine on other walls. Question is can I sand cement render on top of the exisiting multi finish plaster after giving it a good key and seal with pva?

hack off and insulate
 

BigMacks

Member
You doing it yourself Matt

Yeah I am. Not the first time I'm using the trowel with sand cement so don't worry haha.

Did give it a try on one section of the well after giving the plaster a good deep key then cleaning off and sealing with pva. Seems to have adhered well and firm but want to know what the experienced guys think of this and if its practical solution long term.
 

hstoke

Well-Known Member
I have a bowed solid exterior wall that needs levelling out upstairs in bedroom in my Victorian propety so I believe no cavity wall. By most it is out of level by about an inch in middle.

Wall was already plastered with multi finish and bonding applied in some places on top of original lime plaster nearly 20 years ago. Lime plaster underneath is not in such a great condition as you can imagine given the age of property.

I am not really concerned about damp as externally the wall is rendered and had it checked by a damp professional who said the wall is...bone dry (his exact words) after he checked with his machine. Just the usual mould and condensation problems.

Have been advised to use sand cement render with added waterproofer on this wall to level out. Regular BG bonding is fine on other walls. Question is can I sand cement render on top of the exisiting multi finish plaster after giving it a good key and seal with pva?
Any pics of inside and outside walls
 

Vincey

Private Member
I’d insulate too mate after all it is 2021 now not 1921 times have moved on even if a lot on here haven’t lol
 

ChrispyUK

Well-Known Member
I’d insulate too mate after all it is 2021 now not 1921 times have moved on even if a lot on here haven’t lol

mentioned it on another thread Pete that my mates house that I’ve put IPB on pretty much all external walls is now really cosy. He keeps spreadsheets of everything and says his gas bill is down 50%.
 

John j

Mono Don
Yeah I am. Not the first time I'm using the trowel with sand cement so don't worry haha.

Did give it a try on one section of the well after giving the plaster a good deep key then cleaning off and sealing with pva. Seems to have adhered well and firm but want to know what the experienced guys think of this and if its practical solution long term.
Your using THE trowel . @Vincey will want that.


Just fire it on as I love ye as you make me feel like I know what k.m doing .

Which I dont .



But some how keep getting paid



But dont love ye as much as @zombie wombie .
 

BigMacks

Member
I’d insulate too mate after all it is 2021 now not 1921 times have moved on even if a lot on here haven’t lol

But how exactly?! Hack it all off and dot and dab with insulated plasterboard with foil backing I guess....or attach levelled battens to the brick wall and fix plasterboards onto battens?...I suppose two ways to do it.

Either way it's a much bigger job as I have to hack everything off to bare brick that's a big mess. Just want this levelled out so it looks all nice and neat once decorated without the big job. Must be a quicker and proper way. Someone suggested hardwall...
 

hstoke

Well-Known Member
But how exactly?! Hack it all off and dot and dab with insulated plasterboard with foil backing I guess....or attach levelled battens to the brick wall and fix plasterboards onto battens?...I suppose two ways to do it.

Either way it's a much bigger job as I have to hack everything off to bare brick that's a big mess. Just want this levelled out so it looks all nice and neat once decorated without the big job. Must be a quicker and proper way. Someone suggested hardwall...
What’s the wall shape ,is it like a banana can’t u get the wall level instead of bodging it if poss ??
man banana GIF
 

Ktownsend

Well-Known Member
But how exactly?! Hack it all off and dot and dab with insulated plasterboard with foil backing I guess....or attach levelled battens to the brick wall and fix plasterboards onto battens?...I suppose two ways to do it.

Either way it's a much bigger job as I have to hack everything off to bare brick that's a big mess. Just want this levelled out so it looks all nice and neat once decorated without the big job. Must be a quicker and proper way. Someone suggested hardwall...
It can be done cheap or done properly. You cant have both
 

BigMacks

Member
What’s the wall shape ,is it like a banana can’t u get the wall level instead of bodging it if poss ??
man banana GIF
Yeah a banana pretty much describes it lol. Badly concaved and goes in by about an inch in the middle.

Have been told its common in old Victorian properties but not sure.

Others have suggested building a stud over the wall and plaster boarding that but I'll lose too much floor space, like a good inch and half.

Thinking of chipping off top and bottom as much as I can and sticking on vapour control plasterboard using expanding foam. Staying away from dot and dab stuff.
 

bof

Well-Known Member
Yeah a banana pretty much describes it lol. Badly concaved and goes in by about an inch in the middle.

Have been told its common in old Victorian properties but not sure.

Others have suggested building a stud over the wall and plaster boarding that but I'll lose too much floor space, like a good inch and half.

Thinking of chipping off top and bottom as much as I can and sticking on vapour control plasterboard using expanding foam. Staying away from dot and dab stuff.
So your worried about space , it's too much mess to remove but prepared to remove part , you sir are a customer heaven sent lol

Go for what you said it'll work
At least put some fire fixings in for the safety

No offense but all that effort for bodge result lol
 

BigMacks

Member
So your worried about space , it's too much mess to remove but prepared to remove part , you sir are a customer heaven sent lol

Go for what you said it'll work
At least put some fire fixings in for the safety

No offense but all that effort for bodge result lol

Firstly I'm not your customer.
Secondly I'm just after general advice like anyone would be on a forum...you're not obliged to reply.
And lastly how are you so sure it would be a bodge result.

Thanks anyway!
 

bof

Well-Known Member
Firstly I'm not your customer.
Secondly I'm just after general advice like anyone would be on a forum...you're not obliged to reply.
And lastly how are you so sure it would be a bodge result.

Thanks anyway!
Your a customer heaven sent will resonate with most domestic spreads

Secondly you have had lots of advice and I'm entitled to reply
To which I've said you can do that but put fire fixings in

Thirdly bodging is a past trade that required experience and is in fact not a derogatory term ,
but without experience you stand not necessarily to fail but potentially to waste a lot of time and money

I've pointed out that you are prepared to make mess by removing the top and bottom , probably another 10 minutes and the middle will almost fall off but even despite not wishing to loose space you are now suggesting you leave it on and dab on top of the dodgy , now weakened further , lime and BONDING solid EXTERIOR wall seems to be a bit of a strange end result plan but I like your attitude :numberone:
 

BigMacks

Member
Your a customer heaven sent will resonate with most domestic spreads

Secondly you have had lots of advice and I'm entitled to reply
To which I've said you can do that but put fire fixings in

Thirdly bodging is a past trade that required experience and is in fact not a derogatory term ,
but without experience you stand not necessarily to fail but potentially to waste a lot of time and money

I've pointed out that you are prepared to make mess by removing the top and bottom , probably another 10 minutes and the middle will almost fall off but even despite not wishing to loose space you are now suggesting you leave it on and dab on top of the dodgy , now weakened further , lime and BONDING solid EXTERIOR wall seems to be a bit of a strange end result plan but I like your attitude :numberone:

Maybe you misunderstood me or perhaps I didn't explain myself properly.
What I really meant was like flattening down top and bottom, not by removing but other means like sanding down the top and bottom coat of finish, to get this banana wall as flat as possible and then fixing plasterboard by acrylic or other adhesive. Shouldn't have used the term chipping.

I'm just cautious about removing the couple inches of lime plaster/finish on this bowed wall. My concerns are structural related as this wall seems bowed and weak already but then it may well still be strong and firm from the perspective of say a surveyor or engineer.
 

bof

Well-Known Member
Maybe you misunderstood me or perhaps I didn't explain myself properly.
What I really meant was like flattening down top and bottom, not by removing but other means like sanding down the top and bottom coat of finish, to get this banana wall as flat as possible and then fixing plasterboard by acrylic or other adhesive. Shouldn't have used the term chipping.

I'm just cautious about removing the couple inches of lime plaster/finish on this bowed wall. My concerns are structural related as this wall seems bowed and weak already but then it may well still be strong and firm from the perspective of say a surveyor or engineer.
Lol let's keep this going till wine o'clock as it is Friday

Put up a photo of the bow of the wall on the exterior ( from the outside )
 

BigMacks

Member
Lol let's keep this going till wine o'clock as it is Friday

Put up a photo of the bow of the wall on the exterior ( from the outside )

Outside is rendered but you can see the attached image if I put a straight timber against the middle the top goes in a bit so protrudes inwards on the inside wall.

Otherwise looks all relatively flat when looking from outside.
 

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smoother09

Well-Known Member
Outside is rendered but you can see the attached image if I put a straight timber against the middle the top goes in a bit so protrudes inwards on the inside wall.

Otherwise looks all relatively flat when looking from outside.
That’s good work u got his number? :ROFLMAO:
 

bof

Well-Known Member
Outside is rendered but you can see the attached image if I put a straight timber against the middle the top goes in a bit so protrudes inwards on the inside wall.

Otherwise looks all relatively flat when looking from outside.
Ok so assuming the renderer's have gone with the flow I accept the wall is bowed
That said I still think your making the mess inside so to take off all and to foam stick thermal board
Sorry if that's not what you want to hear lol
 

BigMacks

Member
Ok so assuming the renderer's have gone with the flow I accept the wall is bowed
That said I still think your making the mess inside so to take off all and to foam stick thermal board
Sorry if that's not what you want to hear lol

What would you suggest?
 

bof

Well-Known Member
What would you suggest?
Foam stick thermal boards , it's your house so you don't have to use 50 mm
Wickes do these , join online tradesman account and get 10% off

Knauf XPS Laminate Plus Insulated Plasterboard Tapered Edge - 27mm X 1.2m X 2.4m​

Measure down from the ceiling a couple of bricks to the motar joint and write in pencil on cieling so you can put some screws in for fire fixings once set ( 4 per board )
The good bit is you can turn the radiator down
 

BigMacks

Member
Foam stick thermal boards , it's your house so you don't have to use 50 mm
Wickes do these , join online tradesman account and get 10% off

Knauf XPS Laminate Plus Insulated Plasterboard Tapered Edge - 27mm X 1.2m X 2.4m​

Measure down from the ceiling a couple of bricks to the motar joint and write in pencil on cieling so you can put some screws in for fire fixings once set ( 4 per board )
The good bit is you can turn the radiator down

Thanks mate. Yes had a look at those, but also seen 38mm British Gypsum ones with PIR insulation. About a cm more won't hurt I guess.

Anyway hacked off a bit of the wall on top and I'm no plastering expert but I'm sure that's undercoat bonding on top as you can see. A good half inch and more slapped along the top of this wall it seems when it was plastered about 20 years ago. Whoever done it didn't seem to care about the levelling of this wall. No wonder it's coming out so much on top.

Tempted to remove this thick coat of bonding along the top so it wouldn't cause issues when applying and levelling the plasterboards on top....
 

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