some patches of render not sticking

[mango]

hi please help i am plain face rendering a wall in four panels its 1m high and roughly 37m long . i started with a 4:1 scratch coat with plasterciser and s.b.r mixed in the water applied it and then scratched as normal. It was left for a few days i came back gave it a light scrape with my trowel and soaked it down. this is where the fun starts. first panel i mixed 4:1 again (wrong i know but i hadnt done it for a while) and again mixed plasterciser and s.b.r in the water. It got to about the third rub and noticed it slide in odd places and in turn ended up on the floor. only patches though not the whole panel 2nd day: spoke to bostik and changed my mix to 5:1 no s.b.r just platerciser . and again a few rubs down and in odd place can see it start to slide yet again ended up on the floor rang bostik again told them still not sticking and now they are saying im using cem2 cement (rugby) and should be using cem1(portland). but basicly saying im getting air in the mix creating an air pocket but why only in random places does it lift. i have patched them now not great i know but couldnt think what to do 1 other thing is at the top its too thin i know this but builder sat his caps the same thickness as the wall i told him this was wrong so he went around with an angle grinder taking a bit out underneath and told me to blend it in not happy with this but he is paying and i need money. any tips or telling offs would be appreciated

 

[Marshy]

I think you put too much SBR in your scratch coat, its good stuff as designed not to let any moisture penetrate (hence the sliding of your second coat) also perhaps you wet down too much before applying your second coat? And perhaps too much plastaciser ?? I'm not keen how your builder did his bit!!?? Any chance of some pics so the rest of the lads can forward their opinions ??

 

[Arti]

Too much SBR in the scratch??

 

[cassie]

did you wet the wall down to start ?? bostik ?? just read it again mate and i would get someone experienced for your next job and learn off them...

 

[johniosaif]

Weird bit about scraping it, was it not scratched ? You should not scud it to make a key for last coat

 

[mango]

yes i did and bostik make the s.b.r. and i have recently flown the nest so i am on my own

 

[mango]

thanks i can get pics tomorrow would you wet it down then or first pva it or pva in mix or slurry coat or just go for it.............. and most of it is bang on just odd places at about the size of my hawk peels off i have never encountered this before and when i used to mix when we was rendering i chucked admixtures in any old how we never had any problems thats why im flummoxed

 

[mango]

yes i applied first coat and scratched it left a few days then went bak and gave it a light scrape to get the little ridges out what the scratcher leaves so its a nicer surface to work form again

 

[johniosaif]

Slurry coat it without sbr

 

[Marshy]

thanks i can get pics tomorrow would you wet it down then or first pva it or pva in mix or slurry coat or just go for it.............. and most of it is bang on just odd places at about the size of my hawk peels off i have never encountered this before and when i used to mix when we was rendering i chucked admixtures in any old how we never had any problems thats why im flummoxed

Never ever ever PVA on externals mate !!!! :RpS_thumbdn: The lads on here will always help you so long as you don't come across as a ******* try and get them pics up when you can pal :RpS_thumbup:

 

[User___removed]

I think wetting it was the problem.i have just finished one and put sbr in the scratch.wet one panel and topped and it hang for hours.didnt wet the other and it was perfect.

 

[church]

it just gets worse .

 

[beddy]

Air pockets when applying top coat

 

[mango]

thanks for the posts i am grateful. From what ive seen im going to apply a slurry mix and mix with no additives see how i go

 

[essexandy]

Air pockets when applying top coat

Yeah @beddy this is deffo the problem.
I always used to fill my pockets with little pebbles, nice smooth rounded ones with no sharp edges, but being a fat ******* now I find this unnecessary to stay firmly on terra firma.

 

[church]

The problem is these people havent got a clue what there doing thats the problem but is only plastering ,so have you tried pushing a bit harder?:RpS_thumbup:

 

[Bennyspreadsmore]

thanks for the posts i am grateful. From what ive seen im going to apply a slurry mix and mix with no additives see how i go

Mix gripfill in to give a good key.
Way too much plasticiser be your problem

 

[johniosaif]

Bad benny