Making render look good !!

[Kimberley88]

Hello I have bought a house thats half rendered, built in the 80s, the previous owner installed a window at some point and someone made a dogs dinner of the render around it. Uneven, rough patches etc.

Before they sold the house they had it painted in Dulux weathershield. All looks well except the one wall which just looks kack.

I have a mate who is a plasterer and he is happy to have a go at rendering! but has no idea about preparing the wall.

What do I need to do to the wall so the render will stick to the paint, the paint is sound and I have jet washed it and it does not lift, my thoughts are some kind of bonding agent. My mate also suggested tyrolene, but that would look odd on one wall.

Any thoughts or ideas please.

 

[external]

you need a plasterer m8

 

[Kimberley88]

you need a plasterer m8

I have a plasterer but he is not a renderer. He is quite happy to render it but has no idea how to prepare the wall because of the masonery paint. If it was a plastered wall he would PVA.

But his and my understanding is render will not stick to paint.

Taking it off is not an option because I tried a pressure washer and scraping but the paintwork is sound. Removing the render will take too much time and will be costly.

 

[trowelmonkey1]

you need a spatterdash slurry with one part cement and two parts sand and as much SBR as the instructions on the back of the SBR tub tell you, stippled on with a coarse bruch

 

[Kimberley88]

you need a spatterdash slurry with one part cement and two parts sand and as much SBR as the instructions on the back of the SBR tub tell you, stippled on with a coarse bruch

Thanks for that, much appreciated. I always said I would never buy another house with render! still it will keep me out of trouble for a bit.

 

[external]

only tip i've got for you is rendaid,pretty much foolproof ,pre baged an sticks like it to the proverbial woolly blanket!

 

[trowelmonkey1]

looks like good stuff ext. having a read through the product data on the weber site though says not to use it on painted surfaces.

 

[external]

best ive ever used trowel,never seen it fail m8!
edit to say,ive yet to find a product that says it will stick to paint specialy the old oil based stuff.

 

[trowelmonkey1]

good to know exty! nice one mate, always good to find new tricks/products!

 

[Kimberley88]

best ive ever used trowel,never seen it fail m8!
edit to say,ive yet to find a product that says it will stick to paint specialy the old oil based stuff.

External - do you think this will definatley work over dulux weathershield? my plasterer says he can get hold of Rend Aid from keelsupply so it could be a good solution for me.

Will I need to do anything else to the wall before applying rend aid?

 

[1john]

I know the paint is seure now but it may be worth disking through it for a good mechanical key, at the end of the day it doesnt matter what prep you do, if you dont pass the paint, that is what will be holding the render on, what happens when you see the paint fail on the other walls? Would you be worrying about big sheets of render falling off this wall?

That is just the way I see it, people shoot me down if i'm wrong!

 

[Micilin]

I would use (have used) rendaid onto paint where the paint is sound , (or all loose is removed) .

You also need a mechanical key onto paint - if your render is napped or sponged without too many layers of paint on the original, you'll still have a rough surface to some degree.

I also always sparrowpeck the surface for a mechanical key. By this I mean making indents on the surface with a tacking hammer (claw of hammer or scutch hammer) say, every 6-8" apart. I'd wet the wall and brush it to get any dust off before applying the rendaid. This also allows you to check for live spots in the render by listening to the sound. A grinder will give you a key very efficiently, but is very dusty and hard to hear a live spot

An SBR slurry will do the job too, but rendaid is very handy in a bag, you can trowel it on and stipple it or roll it for a key.

I've used both over the years and never had a problem onto painted render outside

 

[external]

if you really want to be sure mesh and pin it,we did some a few years ago and it was the only way to get the guarantee from manufacturer(painted brick) wont be much more work or cost.