Parex Monorex fail

J

JKS Prop

New Member
Hello All.

I am a general builder and undertook an over render to a house in Plymouth. The existing render was solid so it was agreed to use monorex over the top. At the time the only available primer from Parex was Microgobetis 2000. The walls were cleaned and prepared and then a coat of Microgobetis was applied. My plasterer then coated the whole house with Monorex. The job was done in March so the weather was just about right for render. Not Hot, not cold. My plasterer is very experienced in using parex,K rend etc and we have never had any problems.

Two years after the job was completed minor cracks started to appear on the top of the gable end wall. Hairline cracks but everywhere like crazy paving which would show up when wet. Another two years down the line the whole house has gone like it. Nothing has blown but the Parex seems to be very soft. You can scratch it with a finger nail.

We have had the rep and tech guy out from Parex who both said they have never seen this before. Trouble is their boss has said it was all mixed wrong and wiped his hands of it. I cant see that my plasterers mixed the whole house wrong when we have used Parex alot and never had a problem.

Client wants a hack off and re-render. Insurance dont want to know. I have suggested a stabilising solution to harden the render and then paint with a decent paint but she wont go for this.

Anyone else experienced this problem.
Cheers
James
 
The mixing issue is a stretch in my mind. The plasterer wouldn't have been able to spread it if it wasn't mixed.

Parex doesn't need that much mixing anyway.
 
Hi James,

Very strange to hear this, especially with Parex. They have a reputation for being a very good manufacturer of products and do tend to stand by their customers.

What was the substrate the Micro Gobetis went onto? Was a specification raised for the job?
 
Parex Monorex fail
Hi.

The substrate was a sand and cement render. but it was absolutely solid. It was painted but the paint was very good. Like I said, nothing has failed in adhesion terms it just seems that the monorex is soft. We are close to the coast and the house in question does get battered by the weather. Also, there is a lot of algae on properties in the village and I wondered whether this would attack the Parex?
 
i don't what know you've got but it's supposed to be about 20mm thick in harsh weather areas
 
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Contact rend-it.co.uk and see if they will spec it for you, there paint is designed for this and good stuff, will spruce it up and cover the cracking.
My guess is the render over micro on paint is the issue. Parex wouldn't spec that in my experience. The render would only dry on top of the paint and not through it resulting in it not adhering properly and then loses strength under its own weight resulting in cracking and eventual de-lamination.





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Yep lack of adhesion on that from looking, not been sealed on completion resulting in dirt sitting on the surface. I'd knock it off back to substrate and re do. There lies the issue of going over existing renders other than a thin cost t I wouldn't do it, too much weight. Depending on the thickness of the original you could have 40mm thickness on there, that's some pull on the substrate. Hand applied, machine applied, how mixed etc wouldn't make any odds for me.
 
I buy all my render through Encon insulation. I went through it with their Parex chap and he didn't even mention getting parex to spec it. The customer is insistent on a re-rend. Peter Barker said to her that if I contacted them we could work together to sort it out but trying to get hold of him is a nightmare.
 
JKS Prop said:
View attachment 11383 Hi.

The substrate was a sand and cement render. but it was absolutely solid. It was painted but the paint was very good. Like I said, nothing has failed in adhesion terms it just seems that the monorex is soft. We are close to the coast and the house in question does get battered by the weather. Also, there is a lot of algae on properties in the village and I wondered whether this would attack the Parex?
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Is that the original render?
 
JKS Prop said:
I buy all my render through Encon insulation. I went through it with their Parex chap and he didn't even mention getting parex to spec it. The customer is insistent on a re-rend. Peter Barker said to her that if I contacted them we could work together to sort it out but trying to get hold of him is a nightmare.
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I'd insist on a re render aswell to be fair
 
owls said:
Yep lack of adhesion on that from looking, not been sealed on completion resulting in dirt sitting on the surface. I'd knock it off back to substrate and re do. There lies the issue of going over existing renders other than a thin cost t I wouldn't do it, too much weight. Depending on the thickness of the original you could have 40mm thickness on there, that's some pull on the substrate. Hand applied, machine applied, how mixed etc wouldn't make any odds for me.
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Nothing has blown though its solid on the wall. Just soft.
 
Hard to say with out looking I guess. You can't go over with anything then if it's failing and soft.I'd be advising knocking it off. Challenge parex to it, if it's the product, they have the obligation to replace
 
owls said:
I though that was the finish one, colour looks like t30.
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Looks shocking after 4 years when you think you getting a product Maintenance free if that what your told. I'm not an expert on this like yourself but my two penne that worth is at a guess. Them cracks were always there but you couldn't see them they look like shrinkage cracks and like most things setting happens only once. it looks like the s**t in the air that has made it look filthy, has soaked into the cracks and made them visible? Also the sea air will have a lot of salts which maybe having a chemical reaction, making it soft. Did you incorporate a mesh I don't think you mentioned it? What you have now looks shocking and I would want a brand new coat who wouldn't? I would suggest cleaning it first and seal it if it comes up ok and she is happy if not and like you say it's solid maybe an acrylic incorporating a mesh.
 
Like I said, Peter Barker and the techical chap, Steve I think his name was have both looked at it and agreed it hadn't blown. They couldn't understand it.
 
flynnyman said:
Looks shocking after 4 years when you think you getting a product Maintenance free if that what your told. I'm not an expert on this like yourself but my two penne that worth is at a guess. Them cracks were always there but you couldn't see them they look like shrinkage cracks and like most things setting happens only once. it looks like the s**t in the air that has made it look filthy, has soaked into the cracks and made them visible? Also the sea air will have a lot of salts which maybe having a chemical reaction, making it soft. Did you incorporate a mesh I don't think you mentioned it? What you have now looks shocking and I would want a brand new coat who wouldn't? I would suggest cleaning it first and seal it if it comes up ok and she is happy if not and like you say it's solid maybe an acrylic incorporating a mesh.
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A mono is not a maintenance free product,
But if it's sealed with a uv resistance sealer it stops this.
If I was the owner, I'd be insisting on redoing you can't blame them I suppose, I'd be wary going over that as it makes you then liable for it, which I wouldn't want. Once water gets in, it delaminates with wind be hind it. I'd struggle to blame the product, it's always the applicator through lack of knowledge of good practice and/ or weather.
 
JKS Prop said:
Like I said, Peter Barker and the techical chap, Steve I think his name was have both looked at it and agreed it hadn't blown. They couldn't understand it.
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That's no help to you though is it, ask them for feasible solutions then.
 
Without knowing the job, I would have recommended Parex Parinter. I wouldn't have used Micro.

I think the best solution for you is an equalising paint or a hack off. You will need to clean and prime the surface.

Judging from the picture the overhangs are also minimal - I think the staining will also be caused by this

Sadly, I don't think you'll win with the manufacturers, no specification and the wrong material used as a primer.
 
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Looks like I'm forking out for a re-rend then. Thats this year written off. Guess I will have to hack off right back to original blockwork. Then get Parex to spec it and hopefull knock a shipload off the new bags.
 
Plasterers1StopShop said:
Without knowing the job, I would have recommended Parex Parinter. I wouldn't have used Micro.

I think the best solution for you is an equalising paint or a hack off. You will need to clean and primer the surface.

Judging from the picture the overhangs are also minimal - I think the staining will also be caused by this

Sadly, I don't think you'll win with the manufacturers, no specification and the wrong material used as a primer.
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Parinter wasn't available at the time. Came out a couple months after job was complete.
 
I was taught rendering in areas close to the coast with a lot of the elements, was three coat work, don't know if these mono manufacturers have a certain spec for similar areas?
 
JKS Prop said:
Looks like I'm forking out for a re-rend then. Thats this year written off. Guess I will have to hack off right back to original blockwork. Then get Parex to spec it and hopefull knock a shipload off the new bags.
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It's up to you but you need to take control of the job from the customer, maybe give my explanation as to why it looks like that and personally I would blame the dirt showing it up. Tell her YOUR solution which would be to clean it then fully mesh and use an acrylic ( the lads will tell you a spec I don't know them) seal it and give her a ten year guarantee. It should work if it's solid, it's a cheaper alternative and will give you breathing space and a couple of years to worry ;)
 
If you came to this job and it was solid what would be the cheapest alternative rather than hack off? It's been asked plenty of times but not on a background this flat and solid without a paint.
 
flynnyman said:
It's up to you but you need to take control of the job from the customer, maybe give my explanation as to why it looks like that and personally I would blame the dirt showing it up. Tell her YOUR solution which would be to clean it then fully mesh and use an acrylic ( the lads will tell you a spec I don't know them) seal it and give her a ten year guarantee. It should work if it's solid, it's a cheaper alternative and will give you breathing space and a couple of years to worry ;)
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Oh and get the reps to back you up coz they haven't come up with a reason and get them to spec it if they do one for this type of job.
 
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