Plaster vs. F***ing Render

[Cursitor Doom]

I seem to have a natural knack for plastering. Not sure where it comes from, but without wishing to blow my own trumpet, I can achieve a 'perfect finish' freehand with little effort. So when I came to having to rendering a square meter of inside wall, I approached the task with supreme confidence bordering on contempt. What a mistake that was! Unlike plaster, render seems to have an irresistible affinity with the floor - which is where nearly all of it ended up. To add insult to injury, when I was carrying out final smoothing on what modest proportion I had managed to apply, a large patch in the middle simply fell out! Conclusion: use plaster for walls and render for floors and if you need an outside wall rendered, get a proper tradesman in. Anyone else had nightmares rendering?

[harryagain]

The wall was probably too dry. Or dusty. Sucks the water out and the render falls off. Wet the wall down before you start. To make it really strong or if the surface is crumbly, prime with diluted PVA a few times & mix the render up with the same. (Follow instructions on the PVA container.)

[Tim Watts]

I rendered the inside of a fireplace to take a stove.

It did have a tendency to slump - luckily I have not made it too wet or I would have been in real trouble.

I think you need to keep it slightly towards the dry side of the mix spectrum...

[Cursitor Doom]

I did prime it with dilute PVA, but just the once. Immediately prior to applying the render I also re-wet it with a plain water spray. I'm guessing it would have been *even* worse if I hadn't!

[Bill Wright]

Ideally you need a gravity deflector from a tool hire shop. Position it according to the instructions and you can have a localised gravity field that makes the vertical wall effectively horizontal. You have to leave it in place until the render has set, which is expensive because the deflectors are usually rated at 4kW. Well worth it though. After the render is hard you can have a bit of fun. Put the cat on the wall and it will totally freak out!

Bill

[Cursitor Doom]

Thanks for the info, Phil. Well I've been under a misapprehension, then. I always thought render was something you could trowel on as thick as you please. Oh well, it's One Coat plaster for me in future!

[F Murtz]

Link won't work.

[Davey]

It's probably somewhere near the Electric Sheep of North Wales.

[meow2222]

I've always had good results rendering. You were using 1:1:6? or something sloppier? It does tend to disconnect from the wall, the trick is to trowel over it with the trowel at a steep angle. This pushes the render under the edge back to the wall. Repeat a few times & it tends to stay there. I'm not sold on pva, unless the substrate's coming apart. Phil has most likely don e far more rendering than I have though.

NT

[Bill Wright]

That's odd.

Bill

[Cursitor Doom]

Yep, there's clearly a different technique required here for render; what works for plaster doesn't work for S&C. BTW, I'm using the pre-mixed-just- add-water stuff from BnQ which states it's ideally suited to this application.

[Thomas Prufer]

A tip I heard, and have not tried: if the stuff won't stick, add some tile adhesive...

Thomas Prufer

[Phil]

Don't use any PVA unless flakey, ruins the suction. Rendering sand is sharp sand that's been sieved fine, add 5% building/soft sand to make it 'sticky' - no worries then. Use a plasticiser to reduce the amount of water needed. Phil.

[F Murtz]

It must have decided it won't talk to Australians. It says address not found.

[Bill Wright]

I'm sure if the OP googles gravity deflector hire he'll be able to locate the necessary equipment.

Bill

[stuart noble]

Pva reduces the initial grab, but a few extra sweeps of the towel usually sorts that out. I find it produces a better bond in the end. Trouble is, a surface doesn't have to be visibly flakey to be too porous, so I pva by default

[The Other John]

He'll need a reverse polarity one for the southern hemisphere otherwise it will always end up on the floor! ;)

[Vir Campestris]

I was expecting a nice funny spoof, not a 404.

Andy