Delaminating thincoat on renderboard

Shaun86

New Member
Got a problem on a thincoat job we did 18 months ago.
We thincoated 3 houses on same street by the book and no problems at all in Johnstone’s. Then one of the customers had a timber frame extension built which was renderboarded ready for us. We had to obviously use Johnstone’s to match the rest of house we did previous. The boards were dry the temperature was right and no rain as we did it. We used 6mm bead ,high flex basecoat etc. then 18 months passed with no problem until we got called back. You could literally pull the render off in one spot with no effort. The board was clean underneath. We sent Johnstone’s rep down. He said it was wrong board and there a massive problem In market.
The board was resistant multi rend board which is a magnesium oxide one. When looking on google there seems to be a lot of s**t with magnesium boards nationwide. Resistant spec that you can use k rend, Parex, fassa etc etc.
we spoke to k rend rep who said it’s not approved board even though resistant say it is. Spoke with fassa who say don’t go near it . Surely the answer has got to be the fitter should of used knauf aquapanel or rcm . The fitter obviously don’t want to replace board. So we ended up getting a rep from resistant out. They said any other system would work apart from Johnstone’s because it’s cheaper and there something In there basecoat. Argued with me that it’s approved everywhere. They also said just the one side were it’s failed needs re render and the other two sides will be fine. They said because the board is clean underneath it’s been rendered wrong of course. After digging more I found that building control stated no warranty on magnesium boards in 2020. Surely if we pull it off and use another manufacturer it will happen again. All thincoat render we use are similar. The customer wants warranty which Johnstone’s said if it was rcm or aquapanel it should last 30years.
surely it needs to be boarded in the correct board this time.
Any advice off be appreciated
 

Dansouthcoast84

Private Member
ive done plenty of houses in resistant mutli rend. never had a problem.
the nhbc have pulled mgo boards on newbuilds. but resistant still hold a bba they all need to go through nhbc again. its because been aload of cheap chinease boards out.

make sure who ever installed it put boards round right way. just seems strange same property only new part failed
 

Tramp

Well-Known Member
Got a problem on a thincoat job we did 18 months ago.
We thincoated 3 houses on same street by the book and no problems at all in Johnstone’s. Then one of the customers had a timber frame extension built which was renderboarded ready for us. We had to obviously use Johnstone’s to match the rest of house we did previous. The boards were dry the temperature was right and no rain as we did it. We used 6mm bead ,high flex basecoat etc. then 18 months passed with no problem until we got called back. You could literally pull the render off in one spot with no effort. The board was clean underneath. We sent Johnstone’s rep down. He said it was wrong board and there a massive problem In market.
The board was resistant multi rend board which is a magnesium oxide one. When looking on google there seems to be a lot of s**t with magnesium boards nationwide. Resistant spec that you can use k rend, Parex, fassa etc etc.
we spoke to k rend rep who said it’s not approved board even though resistant say it is. Spoke with fassa who say don’t go near it . Surely the answer has got to be the fitter should of used knauf aquapanel or rcm . The fitter obviously don’t want to replace board. So we ended up getting a rep from resistant out. They said any other system would work apart from Johnstone’s because it’s cheaper and there something In there basecoat. Argued with me that it’s approved everywhere. They also said just the one side were it’s failed needs re render and the other two sides will be fine. They said because the board is clean underneath it’s been rendered wrong of course. After digging more I found that building control stated no warranty on magnesium boards in 2020. Surely if we pull it off and use another manufacturer it will happen again. All thincoat render we use are similar. The customer wants warranty which Johnstone’s said if it was rcm or aquapanel it should last 30years.
surely it needs to be boarded in the correct board this time.
Any advice off be appreciated
Resistant was revoked from nhbc because of continued failures across Europe, they should pull them off the shelf’s,
Johnstons won’t recommend Because they haven’t tested and won’t on magnesium boards nothing to do with resistant, They are failing on all brands of render continuously, Most manufacturers are staying clear
 

Tramp

Well-Known Member
ive done plenty of houses in resistant mutli rend. never had a problem.
the nhbc have pulled mgo boards on newbuilds. but resistant still hold a bba they all need to go through nhbc again. its because been aload of cheap chinease boards out.

make sure who ever installed it put boards round right way. just seems strange same property only new part failed
Resistance was revoked because of their own failures and there’s been plenty they have even had their BBA revoked in the past
 

Shaun86

New Member
Thanks for replies, resistant rep has been down and wrote a report. Boards are perfectly fine of course. The fitter has built it wrong . Not proper ventilation at bottom n top. Which I understand has to be right . We have rendered it wrong apparently. The board must of had dust on it. We put it on in minus temps. Dog pissed on it. Blah blah blah. Utter b*ll***s . After all that it says at the bottom if you re render it again it might work fine or it may not. A load of crap. Every manufacturer we use say don’t go near them . The guys house I have known for years. it needs sorting
 

MIXERMAN

Well-Known Member
There seems to be a lot of agro involved in this new fangled render stuff, never tried it . But normal s and c is fine ,apart from cracks.
 

Bigstevehammer

Well-Known Member
There seems to be a lot of agro involved in this new fangled render stuff, never tried it . But normal s and c is fine ,apart from cracks.


Seing plenty of mono with cracks now,fully meshed etc..nothings really fool proof…
S&c included…no doubts someone will be along soon with threads of a mud hut in Africa with reinforced fibres and shimmery quartz and we will be all over it…,Zimbabwe shimmer..


Heard it here first,can hear Ryan’s mouse running in the wheel…where is this stuff
 

essexandy

The Lake Governor
Seing plenty of mono with cracks now,fully meshed etc..nothings really fool proof…
S&c included…no doubts someone will be along soon with threads of a mud hut in Africa with reinforced fibres and shimmery quartz and we will be all over it…,Zimbabwe shimmer..


Heard it here first,can hear Ryan’s mouse running in the wheel…where is this stuff
Mono is only coloured sand, cement and lime isn't it? Why wouldn't it crack?
We've been using mesh in sand and cement for years now, that's what reduces the chances of cracking.
 

Vincey

Private Member
I don’t often use thincoat but on the ones I have done I always use Knauf Aqua panel , I don’t trust all the other cheaper boards , one time I bought £250 worth of them from merchants to be told they weren’t on Weber approved list , took them back and lost 20% for returning them but was the best thing I done as getting a come back on any thincoat system like that would cost us a bomb to redo

The Knauf aqua panel rep is a top bloke also very responsive and helpful any time I’ve asked which is just what we need on jobs , same as Weber
 

Bigstevehammer

Well-Known Member
Mono is only coloured sand, cement and lime isn't it? Why wouldn't it crack?
We've been using mesh in sand and cement for years now, that's what reduces the chances of cracking.


Even with jobs with eml etc,still plenty of cracking…if the house wants to move it’ll move??…wether it’s mesh or whatever,it’ll do it’s thing,..I think mono and sand and cement is s**t…
Everyone to their own
 

John j

Mono Don
Even with jobs with eml etc,still plenty of cracking…if the house wants to move it’ll move??…wether it’s mesh or whatever,it’ll do it’s thing,..I think mono and sand and cement is s**t…
Everyone to their own
Ain't there a video on you tube . Where they put some silicon on a plasterboard and bend it to max and silicon doesn't crack
 

MakeItSmooth

Well-Known Member
I remember leaving some Maite in a Gorilla tub, thinking I'd just flex the tub and pop it out. f**k**g stuff was as flexible as the tub lol

Same story with rapid-flex tile adhesive :confused:

Maybe there's a clue in the name, but that didn't stop me learning the hard way!
Chuckle TPF.gif



We left bout a third of johnstones base coat in a gorilla tub. I said I.ll bang it out later . Will it f**k come out. I had lump hammer on it threw it against flags and it still won't come out

Yeah, and a lump hammer just ends up cracking the bucket... (even a Gorilla / flexi)

Oh well, you live and (hopefully) you learn! :birra:
 

Monkey Boy

Well-Known Member
I remember leaving some Maite in a Gorilla tub, thinking I'd just flex the tub and pop it out. f**k**g stuff was as flexible as the tub lol
We left bout a third of johnstones base coat in a gorilla tub. I said I.ll bang it out later . Will it f**k come out. I had lump hammer on it threw it against flags and it still won't come out
I spend alot of my time doing stuff like that
 

Bigstevehammer

Well-Known Member
Ain't there a video on you tube . Where they put some silicon on a plasterboard and bend it to max and silicon doesn't crack

YouTube ain’t my friend mate at 1 o’clock in the morning and a belly full of beer…all sorts of worm holes…if I type in silicone crack??….it’d be another night of explaining to the missus
 
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