How to remove incorrect PVA

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boaz

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I have a question, but will supply the history first. I have a block wall 30 yards long by 2'6" high and 9" wide which separates my raised lawn from my patio, the top capping is York slabs. During 2012/13 winter with all the hard frosts, and 2013/14 with all the rain, it has blown in 6 places to a diameter of 18", always starting wider at the top and tapering down to the bottom, so I think the water has been running over the capping slabs, and between the block/render interface. My Grandson who wants to be an architect, but wants to get his hands dirty fist took some courses during the winter for bricklaying/plumbing etc before he goes to college this September said he would do it as this was not covered in any courses and wanted some experience. So he started knocking all the blown parts off, and with that done, the wall is made of concrete blocks 18"x9"x4" laid flat. He then painted the exposed parts with 5:1 PVA, allowed to dry, then applied 3:1 coat last week. ( this is water to PVA). He left the 5ltr. container for me to dispose of. It is manufactured by Everbuild type 501, but I noticed it said "Internal use only". Having found your site, and read many of the excellent posts, it would appear he has got this incorrect, so at last I come to my question, and thank you for staying with me !!!:-
  1. I have dug down behind the wall where the soil is up to within 9" from the wall top, and the wall is coated with a very thick black substance, almost rubbery, and the blocks are laid on good footings.
  2. The render is mortar 1/2" thick on the front exposed part of the wall.
  3. I have put a 500 volt megger on the block work, contact spaced at 1/4" intervals and the complete face and exposed blocks measure infinity, so there is no damp getting through the wall at all.
Given this situation, would the "Internal Use Only" PVA be alright as the test in 3 above proves the wall is totally dry, or if not, how would I remove it from the concrete blocks, the only way I can think of is a dilution of sulphuric acid, but there would be some reaction with the cement in the concrete blocks, not sure what the long term problems might be for that.
Upon his return, he was going to apply a 1:1 coat of PVA and then apply the mortar rendering with some washing up liquid added to it, whilst the PVA is still tacky, then apply a Snowcem colour coat, finished with a clear silicon waterproof coating - what do you think?. I don't want to put the lad down, as he is keen to do the job, and in this day and age is a good thing.
Any advice would be most welcome, and apologies for such a long drawn out question !!!!.
Kind Regards,
boaz
 
This could be a very costly mistake for you and your son maybe go with an SBR for a start (search the forum) forget Pva
 
PVA is water soluble so while you may not be able to remove all traces of the pva a hose or jet wash should in theory remove the majority of it ! it would not hurt to give it a scrub with a stiff brush when wet and wash off again. Once you are sufficiently happy you have cleaned it best you can start again with SBR
 
He only coated the exposed parts with pva. 5:1. Wouldn't worry about it. A few weeks in the rain or a good pressure wash Would sort it.

If you posted a pic or 2, you would get a lot more help. Are you going to finish it with a smooth render


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cooptaza said:
He only coated the exposed parts with pva. 5:1. Wouldn't worry about it. A few weeks in the rain or a good pressure wash Would sort it.

If you posted a pic or 2, you would get a lot more help. Are you going to finish it with a smooth render


Sent from my iPhone using The Plasterers Forum
Click to expand...

Are u still in Ireland.
 
flynnyman said:
This could be a very costly mistake for you and your son maybe go with an SBR for a start (search the forum) forget Pva
Click to expand...


Thank you for your advice "search the forum" - I have done that and it took a few hours !!. Before I do what has been suggested, I would like to clarify in my own mind what is happening, as there appears to be a bone of contention within your discipline. If you would be kind enough to answer the following points I would be much obliged, as then I shall be able to inform my Grandson when he returns from holiday next week, what he has done incorrectly and why.
(a) Given that I have proved that the blocks are completely dry ( less than 1 microamp conduction at 500 volts), once the PVA has dried completly - ( same test will be carried out ) there will be a membrane seal across the blocks.
(b) When the binding coat is applied, and still tacky, the mortar mix will be applied, this will contain, say, 20% water.
(c) Given the PVA is water soluble, it will try and revert back to its liquid form from its solid form, and mix with the water/mortar mix that has been applied, therefor, the PVA will by capillary action be sucked into the mortar mix, which is all to the good.
(d) At this point, the only moisture that will be applied to the PVA will only come from the front of the blockwork, as the the rear has been "tanked" - I think that is the expression, as my previous tests confirmed.
(e) When the mortar is sufficiently dry, then floating over it and sponge finish it will complete the task.
(f) This will now be covered with plastic sheeting to allow the blocks/mortar and semi fluid PVA to dry out, and no rain will be allowed to penetrate the front face.
(g) The complete structure will be tested each day, until the 500 volt test is passed, ie, all dry, and maintained for 3 days.
(h) So by this time a stable substrate and bond will have been produced between the blocks and the mortar - (other than molecular migration).
(i) A colour coat of "Snowcem" will be added, and again allowed to dry out completely, then 2 top coats of silicon weather proofing added - again leaving for another week for all to be completely dry, then the protection covering may be removed.
Could this be a possible way out for me, or am I still in deep and expensive trouble ? your advise would be most welcome. Incidentally, do you know when SBR was introduced to replace PVA which has been in production for many years.
Kind Regards,
boaz
 
I will just answer the last bit SBR wasn't introduced to replace PVA they are for to different things do some research on each product and their uses it will become clearer.
 
cooptaza said:
He only coated the exposed parts with pva. 5:1. Wouldn't worry about it. A few weeks in the rain or a good pressure wash Would sort it.

If you posted a pic or 2, you would get a lot more help. Are you going to finish it with a smooth render


Sent from my iPhone using The Plasterers Forum
Click to expand...


Thank you for your reply, the render is 1/2 inch thick, so this will be the final finish. Whether it will be a smooth one is in the lap of the Gods, and my Grandson !!!,
Kind Regards,
boaz
 
flynnyman said:
I will just answer the last bit SBR wasn't introduced to replace PVA they are for to different things do some research on each product and their uses it will become clearer.
Click to expand...

Thank you for that, I made a mistake, I meant to say, "What was used before SBR was available and PVA was" - apologies for not making myself clear to you, I will now research the relative qualities of SBR and PVA and their applications.
Kind Regards,
boaz
 
SBR is used as a waterproofer and a primer, externally years ago PVA Mixed with cement was used as a primer but not as a waterproofer.
 
Give us a picture. Was there holes in the blockwork or was it left smooth from the old render


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flynnyman said:
SBR is used as a waterproofer and a primer, externally years ago PVA Mixed with cement was used as a primer but not as a waterproofer.
Click to expand...

Good morning flynnyman
Thank you for your reply, so in essence, nothing wrong with PVA, just not waterproof ?, so, if it was made waterproof, there would be no problem, and your original post of "A very costly mistake" maybe avoided by me - hence question .
As the Moderator of this site, you must be well versed in your profession, and I value your comments therefor, would you be kind enough to answer my posting fully, not just the last part, as I must have a definitive answer by this coming Friday. Thank you for your patients to date, but you only learn by asking questions, and receiving professional answers.
Kind Regards,
boaz
 
put up a fekin picture... You only primed it 5:1. It will only stop the suction a bit, continue with your plastering, no harm done. But put up a picture so we can advise you on the how to finish it
 
Like what's been said above don't worry about it just get on with it, it will be a costly mistake coz your grandson has no experience and is making basic errors before he has even put a mix on.
 
"apply the mortar rendering with some washing up liquid added to it"

Another job to sort out. Well at least they keep us in work.
 
alexpryor said:
"apply the mortar rendering with some washing up liquid added to it"

Another job to sort out. Well at least they keep us in work.
Click to expand...

It used to function very well in the "old days" I am lead to believe - but then again, so did cyanide for a facial cream for Ladies in the 1900's !!!

Kind Regards,
boaz
 
DannyMac said:
Do the 500 volt test on your grandson, then get in a proper plasterer. :RpS_thumbsup:
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Thank you so much for that DannyMac - but may I respectfully suggest that before you came to be at the top of your profession, you must have had to learn from a person much more educated than you at the time !!!
Kind Regards,
boaz
 
cooptaza said:
put up a fekin picture... You only primed it 5:1. It will only stop the suction a bit, continue with your plastering, no harm done. But put up a picture so we can advise you on the how to finish it
Click to expand...

Please read my post :- I am not asking how to finish the work involved, just the application of using PVA which may/is possibly incorrect - therefor, photographs are totally irrelevant.
Kind Regards,
boaz
 
flynnyman said:
Like what's been said above don't worry about it just get on with it, it will be a costly mistake coz your grandson has no experience and is making basic errors before he has even put a mix on.
Click to expand...

You are quite correct - he is making basic errors - but without professional advice, and patients, he will never learn, and that is what life is all about - you had to learn from somebody in your early days, when you were also possibly considered to be utterly and totally useless, now, having been fully trained and qualified, you are able to pass on your experience in this subject to many others, that is what it is all about at the end of the day.
Kind Regards,
boaz
 
Thank you all Gentlemen for your advise and suggestions, but I think it is now time to close this discussion, as it appears to be proceeding into nothing that is constructive. Many thanks to you all,
Kind Regards,
boaz
 
boaz said:
Please read my post :- I am not asking how to finish the work involved, just the application of using PVA which may/is possibly incorrect - therefor, photographs are totally irrelevant.
Kind Regards,
boaz
Click to expand...


Yes you got your advice on the PVA on a number of occasions and then some. If you felt that strongly about it you should of said in your post - please don't offer advice about anything else but the PVA.



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Yes the PVA is incorrect, so give it a good wire brushing, that will break up the PVA then SBR stipple, re render whilst stipple green problem solved.

P.s we always get extras following Architects decisions
 
boaz said:
You are quite correct - he is making basic errors - but without professional advice, and patients, he will never learn, and that is what life is all about - you had to learn from somebody in your early days, when you were also possibly considered to be utterly and totally useless, now, having been fully trained and qualified, you are able to pass on your experience in this subject to many others, that is what it is all about at the end of the day.
Kind Regards,
boaz
Click to expand...
That is correct but I didn't get my granddad to go on a forum and find out for me that's not really the way I was taught and I say again taught. Also it took a bit more than him asking basic questions for me to go on and render his wall.
 
boaz said:
Please read my post :- I am not asking how to finish the work involved, just the application of using PVA which may/is possibly incorrect - therefor, photographs are totally irrelevant.
Kind Regards,
boaz
Click to expand...

I feel sorry for your grandson. You sound like a knob. He has made a small mistake. Not an expensive one. There has been no harm done.



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LOL just tell him to render it, it'll probably be fine. What's the worst that can happen? It'll blow and he'll get more practice.

Talk about mountains and molehills....
 
cooptaza said:
I feel sorry for your grandson. You sound like a knob. He has made a small mistake. Not an expensive one. There has been no harm done.


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COOPTAZA :- I do not know what a "KNOB" is, apart from an item used to open a door - I have NEVER stated that "An expensive one" has been done by him - THAT falls to your MODERATOR on this site see he said that not me, hence the questions that followed - so before engaging your fingers, I suggest you engage your brain, and have a look at the postings, All I have done is try to receive some answers to my original postings, as guidance was required on my part, and as far as the Moderator is concerned, I am not asking questions on my Grandsons behalf, only trying to receive some educated answers so that I am able to suggest to him what may have not been correctly done by him, and then for him to find out why - it is called "Helping". I take it that both you and the moderator did not have an understanding of what I have done electronically to try and help him, hence no fully answered replies to my questions by you both. As I stated before, I think it is time for this posting to end, so let us do just that.
boaz.
 
Whatever you do electronically makes no odds to the job so no point answering it get your hand in your pocket and pay a plasterer to mess it up ;)
 
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