DIY Doctor UK DIY Forums

What I'm I doing wrong?When I try and render an outside wall with a sand/cement mix,then use a featheredge or a darby on it to level it,it brings all the render off with it.Do you put the render on then use the straight edge straight away or wait for render to go off before using it.Any tips on using a darby would be very appreciated

Hi AndyB,

Im not sure on your experiences in plastering/Rendering.
The easiest way for you I would say firstly to apply the render to the wall using a plastering trowel. (Say about a few sq. metres) to start with.
Let it firm up a bit, Then try using a featheredge, start from the bottom bringing up the featheredge in a zig zag motion.
When the render has almost firmed up use a lighty damp sponge float working in a curricular motion.
Just practice with it, rendering is a lot more difficult than plastering, Even for us pro`s it can be hard some times ;)
By the way are you using plastersizer in your mix? and applying pva to your walls first?
The best way i find to do your mix is by using 70 % cerment and 30 % sand, add some plastersizer, also try to aviod using sand that contans any clay.
Hope this helps Leigh. > link deleted see terms and conditions

Thanks for tips.Will have another go! One point you made which surprised me was the mix.I always thought you had more sand than cement i.e. a 4 to 1 mix of sand to cement.Have I got it wrong :oops:

You can add more sand in your mix to how i described early, my self i use more cement than sand but thats just me.

The most comon way for a render mix would be cement 4 parts, soft washed sand 10 parts, Sharp sand 2 parts - this gives a ratio of 3-1 a strong mix

I would say to just practice with the mix and rendering, but also try to stay with the same mix though out your job, also if your going to use sharp sand it can make more difficult as the stones can drag lines in the render.
Are you doing the job in two coats?

you say you use a sponge float,are they any good, i use the normal floet, do you sponge it over with a hand sponge or just the sponge float

I normally use a sponge float, It all really on depends on the job, the weather and how your mix is done.