Skim coming off S&C undercoat help needed

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Daveo82

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I had walls take back to brick and then S&C undercoat which was left to cure for 4/5 days then 2 coats of thistle multifinish applied

After a couple of weeks a few cracks appeared and then another couple of weeks and a few hollow patches and more cracks

I have removed a patch of skim and it was very easy to get off like it wasn't adheres well to the S&C I have included pics below and tried to go into more detail than in a previous thread

The S&C has no cracks at all in it and is solid no hollow patches it is also an internal wall with no damp can anyone help with why the cracks may have appeared and the skim blown

Could it be the key or should a binding agent have been used over the S&C? If I removed all the skim and applied blue grit before re skimming could that solve the problem?

Just spoke let k British gypsum and they said th S&C undercoat should have been left to dry for weeks is that true? And also a bonding agent used not just multi finish straight into S&C can anyone confirm?

I really appreciate your help in advance
 

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Really??? Is that the problem then? And if so what can be done to rectify?

it looks like they have run a bark roller over the sand and cement,poor key, the skim coat looks very thick, not 2mm. reason ? fake expert !
 
Come on Daveo82 tell the truth have you done this job and now you are in the poop because you don't know what your doing ?:whistle:
 
it looks like they have run a bark roller over the sand and cement,poor key, the skim coat looks very thick, not 2mm. reason ? fake expert !
They used a scratcher from toolstation, only know cos I got one :(
 
it looks like they have run a bark roller over the sand and cement,poor key, the skim coat looks very thick, not 2mm. reason ? fake expert !
Ho could you get 2 skim coats 2mmthick that would be 1mm per coat surely tags impossible
 
No mate 2 experienced plasterers paid a good few quid for it as well is it that bad????
If they are that experienced(which i doubt) i would ask them to come back and tell you how they are going to sort it out .
 
If they are that experienced(which i doubt) i would ask them to come back and tell you how they are going to sort it out .
I have mate and they have said take off loose skim blue grit and reskim with plastic meshing in the skim to hold it But I'm losing confidence and need it down right this time
 
Your wall not floated, all they done is put that scarifier on it instead of rubbing it up with a devil float, there's not enough key but that's not the whole story
What is the whole story then mate - sorry to go on but I've it 3 kids sharing a bedroom at the moment and this is really getting to me - they are back Monday and I need to know what to say to them - thank you for your time
 
What is the whole story then mate - sorry to go on but I've it 3 kids sharing a bedroom at the moment and this is really getting to me - they are back Monday and I need to know what to say to them - thank you for your time
I can't give you advice, you have to get someone out local to you to have a look in person even if it costs you, it's all well and done looking at a picture and trying to figure it out what's what and pointing fingers.
 
I can't give you advice, you have to get someone out local to you to have a look in person even if it costs you, it's all well and done looking at a picture and trying to figure it out what's what and pointing fingers.
Of course I get that just other tradesmen don't like finishing other people's jobs so will be a struggle
 
View attachment 16519 I had walls take back to brick and then S&C undercoat which was left to cure for 4/5 days then 2 coats of thistle multifinish applied

After a couple of weeks a few cracks appeared and then another couple of weeks and a few hollow patches and more cracks

I have removed a patch of skim and it was very easy to get off like it wasn't adheres well to the S&C I have included pics below and tried to go into more detail than in a previous thread



The S&C has no cracks at all in it and is solid no hollow patches it is also an internal wall with no damp can anyone help with why the cracks may have appeared and the skim blown

Could it be the key or should a binding agent have been used over the S&C? If I removed all the skim and applied blue grit before re skimming could that solve the problem?

Just spoke let k British gypsum and they said th S&C undercoat should have been left to dry for weeks is that true? And also a bonding agent used not just multi finish straight into S&C can anyone confirm?

I really appreciate your help in advance


BG are right it should be left for a month. But no body does it. That could be 0ne reason for the failure but don't think it is. Could be the sand and cement mix. But I'd say there is not enough key on the sand and cement it should look like this.

20161213_144411.jpg
 
Just take off skim where lose blue grit and skim it the next day. Name and shame the prick that did the work
 
Must admit the first things that you think when you see it is lack of key.
Could be other issues as others say but to me it's lack of key.

Surely however experienced or inexperienced you are cant surely think that is an adequate key they need their head testing
Looks like a tile float

The mind boggles sometimes.
 
Just take off skim where lose blue grit and skim it the next day. Name and shame the prick that did the work
Thank you so much mate really appreciate the helpful answer and advice

On the walls where it has cracked but not as bad is it worth hacking off them bits as well? And the bits that sound solid will they be ok now as its been a month it could it go so better to hack off all skim and start again after blue gritting?
 
Must admit the first things that you think when you see it is lack of key.
Could be other issues as others say but to me it's lack of key.

Surely however experienced or inexperienced you are cant surely think that is an adequate key they need their head testing
Looks like a tile float

The mind boggles sometimes.
Thank you mate seems like it's the key then wil blue gritting it be enough or should I get them to scratch it up a bit as well or is it too late now it's set?
 
Just take off skim where lose blue grit and skim it the next day. Name and shame the prick that did the work
Sorry mate one last thing do they need to ova before or after blue grit or just blue grit - as I'll check but want to know what I'm talking about
 
Sorry mate one last thing do they need to ova before or after blue grit or just blue grit - as I'll check but want to know what I'm talking about
If your going to go the grit route don't pva after
the grit acts as a mechanical key and suction control.

I'd be tempted to rough it up as well.
 
Why would you name and shame them though not like they've ran off at least they decency to fix it the skim job doesn't look that bad.
They've been great come back not asked for more money etc I don't have a problem with them at all I actually like them nice fellas just concerned about the work and want to tell them what I want done to rectify it - do you agree it looks like the key is the issue?
 
If your going to go the grit route don't pva after
the grit acts as a mechanical key and suction control.

I'd be tempted to rough it up as well.
What's the best way to rough it up as the S&C is set hard now?

I honestly really appreciate the time you have taken to come back to me with advice thank you
 
Looks very thick skim.
Looks like a tile float was used.
I personally skim sand and cement whilst still "green", most often the day after rendering. Mine has never come off.
 
What's the best way to rough it up as the S&C is set hard now?

I honestly really appreciate the time you have taken to come back to me with advice thank you
I'd grind some groves in it in a diamond criss Cross pattern not too deep or it will show through skim.

Agree with @Dropsalot it looks very thick
 
Looks very thick skim.
Looks like a tile float was used.
I personally skim sand and cement whilst still "green", most often the day after rendering. Mine has never come off.
A few people said thick skim so I measured the bits I hacked off max thickness is 4mm most is 3mm is that ok?

Do you also think the key is the issue?
 
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