12.5mm Plasterboard Fixed Directly onto Concrete Block

[Self Build]

A semi finished house has 12.5mm plasterboard fixed directly onto sand and cement concrete block walls, which appear to have been straightened and plumb using sand and cement floated off. The boards are screwed on using plugs and regular screws. My understanding is there has been something like No More Nails adhesive used also.

Is this OK in the long term or do the boards need changing? With respect to dot and dab, timber baton methods etc. I am assuming there is no mechanical reason why these boards should be pulled off the wall before skimming.

These are internal walls. The external walls have insulated plasterboard using mechanical fixings.

 

[Monkey Boy]

So people screwed and plugged plasterboards to a wall, also used gripfill whatever, then realised they are not straight, true, plumb, and dubbed them out with sand and cement? Never skimmed them?
Is that right?

 

[Self Build]

No. They put sand and cement render on the blockwork behind the plasterboard, (possibly to fill out the low spots on the wall blockwork to level and straighten the wall.)

I do not think it was a full uniform plastering of the entire wall.

Then the plasterboards were fixed onto the now level & plumb wall. I assume the intention was to tape and joint rather than skim and paint the boards. .

However now the owner wants to finish the job and wants skim on the plasterboards.

 

[Dollar]

A semi finished house has 12.5mm plasterboard fixed directly onto sand and cement concrete block walls, which appear to have been straightened and plumb using sand and cement floated off. The boards are screwed on using plugs and regular screws. My understanding is there has been something like No More Nails adhesive used also.

Is this OK in the long term or do the boards need changing? With respect to dot and dab, timber baton methods etc. I am assuming there is no mechanical reason why these boards should be pulled off the wall before skimming.

These are internal walls. The external walls have insulated plasterboard using mechanical fixings.

No trackers /plasterer visited your property

Wakey Wakey

 

[bobski]

Sounds like someone f**k*d up somewhere, and then decided to sort it out by f**k**g it up even more.

 

[Self Build]

To revert back to the original question.

Is there any mechanical reason why these plasterboards cannot be finished? Even by taping and jointing at this stage?

Taking them all down sounds drastic

 

[Monkey Boy]

If they are fixed good it doesn’t matter what method on internals

 

[Self Build]

If they are fixed good it doesn’t matter what method on internals

They are definitely solid

 

[Steve Brown]

To revert back to the original question.

Is there any mechanical reason why these plasterboards cannot be finished? Even by taping and jointing at this stage?

Taking them all down sounds drastic

There are methods and standards for a reason!
The walls in question will probably not be plumb, fixed to the background enough and will most likely crack, that is your answer.

Why it will most likely fail is known by time served plasterers because they have learned industry standards and what materials to use with different specifications.

 

[Self Build]

There are methods and standards for a reason!
The walls in question will probably not be plumb, fixed to the background enough and will most likely crack, that is your answer.

Why it will most likely fail is known by time served plasterers because they have learned industry standards and what materials to use with different specifications.

As of today, the Internal walls have just been taped and jointed. Will be painted in the next couple of weeks. What may be may be.

Just to clarify based on further detective work:

Original blockwork was not bad, but there were patches that needed levelling out with a light amount of sand and cement render. Rather than a full wall render, the patchwork was done instead. The 12.5mm plasterboards were fixed onto the wall using screws and some kind of grab adhesive.

Plasterboards were solid on the walls. Is there reason to be concerned that cracking will take place where the boards are taped and joined?

 

[Steve Brown]

As of today, the Internal walls have just been taped and jointed. Will be painted in the next couple of weeks. What may be may be.

Just to clarify based on further detective work:

Original blockwork was not bad, but there were patches that needed levelling out with a light amount of sand and cement render. Rather than a full wall render, the patchwork was done instead. The 12.5mm plasterboards were fixed onto the wall using screws and some kind of grab adhesive.

Plasterboards were solid on the walls. Is there reason to be concerned that cracking will take place where the boards are taped and joined?

If I was tacking a 8'×4' plasterboard to a studwall with studs a @400mm centres then I'd use approx 48 screws. If that was to a ceiling the that would increase to 63 screws.
How many screws are fixing your boards to the walls? that is your dilemma.

 

[Self Build]

I think people have misunderstood the query

1.Internal Dividing Walls only. Not external walls.

2.There were spots on the wall that were not fully level/plumb so sand and cement was used in patches to level the walls BEFORE the plasterboards were fixed to the wall

3.The plasterboards were then screwed directly onto concrete block wall, (with some adhesive also used such as no more nails.)

4.The boards have now been taped and jointed. A full skim will not now go ahead. Is there any reason to be concerned about cracking in the joints?

There were no batons, the plasterboards are not dotted and dabbed. They are fixed directly onto concrete block internal walls that were levelled as appropriate in spots first.

 

[essexandy]

If I was tacking a 8'×4' plasterboard to a studwall with studs a @400mm centres then I'd use approx 48 screws. If that was to a ceiling the that would increase to 63 screws.
How many screws are fixing your boards to the walls? that is your dilemma.

To be fair Steve that is more fixings than the board manufacturer's specify.

 

[Self Build]

To be fair Steve that is more fixings than the board manufacturer's specify.

Whatever the number of fixings is, I am not worried about, it is whether being fixed manually will lead to cracking down the line.

I think there were actually 24 screws used per 8 x 4 Sheet

6 rows of 4 screws plus probably half a tube of grab adhesive across the back.

So many people say it is not good practice to fix 12.5mm plasterboard directly onto a masonry block wall that I want to find out exactly what the risk is?

 

[essexandy]

Whatever the number of fixings is, I am not worried about, it is whether being fixed manually will lead to cracking down the line.

I think there were actually 24 screws used per 8 x 4 Sheet

6 rows of 4 screws plus probably half a tube of grab adhesive across the back.

So many people say it is not good practice to fix 12.5mm plasterboard directly onto a masonry block wall that I want to find out exactly what the risk is?

I know you don't care about the number of fixings, I was replying to Steve.
You may have noticed that I haven't replied to any of your questions and there's a reason, I can't be bothered discussing anything with someone who is only interested in doing bodge job, because it suits them to.
Anyway good luck with it all.

 

[Self Build]

I know you don't care about the number of fixings, I was replying to Steve.
You may have noticed that I haven't replied to any of your questions and there's a reason, I can't be bothered discussing anything with someone who is only interested in doing bodge job, because it suits them to.
Anyway good luck with it all.

Number 1: I did not do the job

Number 2: I am trying to get advice for the person where the job was stalled and restarted

I thought this forum was for queries, to find things out? Perhaps I am wrong.


I did not seek answers such as why not dot and dab (not possible in this job as boards were up already) or why not use batons (also not possible in this job) as boards were already on the wall. Yes there are probably better ways, yes there are probably best practice ways. However this is not the case here.

I posted on 13th August, the unfinished job was completed on 15th August. Ultimately the job proceeded with the boards staying on the wall and the boards being taped and jointed. I wish to find out what the risks are in terms of how the job was done?

Perhaps there are minimal risks, and perhaps it will hold up for many years to come. In that case, then fair enough. You mention botched job, if this is the case, then what is going to be the long term problem?

I am not sure what the issue is with my genuine query?

 

[Steve Brown]

To be fair Steve that is more fixings than the board manufacturer's specify.

They spec a max 8" between screws on ceilings ( I do 6") and they spec a max 12" on wall studs ( I do 8").
I worked with an old school plasterer that used them spacings as that was the spec when using nails (he insisted).
It's like how many rounds do you use to shoot someone... I use what's in the magazine then reload.

 

[ChrispyUK]

I am not sure what the issue is with my genuine query?

Because everyone is trying to be honest. It may be fine, however there’s no guarantee.

If you had an empirical answer, then you wouldn’t be posting on a forum.

 

[Self Build]

Because everyone is trying to be honest. It may be fine, however there’s no guarantee.

If you had an empirical answer, then you wouldn’t be posting on a forum.

Thank you for the concise answer.

That makes more sense than any other answer.