How to get the correct render finish

[Azurite320]

I need to hack off and replace about 1/2 sq metre of blown rendering to the front wall of my house, under a window.
Is there a premixed render generally available or do I need to mix the render? If so, what is the recommended mix and how do I go about getting the same rough texture?

 

[trowelmonkey1]

can't say for the finish without seeing it so maybe upload a pic?

regarding the render itself, mix it yourself, for the scratch coat people seem to go for a 4:1:1 with plasticiser/waterproofer (4 plastering sand:1 cement:1 lime)

then float coat with a mix of 5:1:1 and plasticiser, rub it up with a float to consolidate the surface but not too soon OR to late.

there has been a post recently about when to rub up.

 

[Azurite320]

Many thanks for the answer.
I'll try the mixes suggested and see how rogh the surface is.
I guess the hardest thing to do is to get it to match the existing render.

 

[trowelmonkey1]

the surface won't be anything to do with the mixes, the surface will be created by how you finish the render, i.e.just with a poly float or a sponge too or by throwing pebbles into it and so on.

getting it to look like the existing render will be nigh on impossible IMO, why don't you consider taking of a complete square the width of the window and from the window sill to the bottom of the render? would leave you straight lines at worst and wouldn't look as bad as random patches.

 

[Alastairreid]

getting it to look like the existing render will be nigh on impossible IMO

agree with that! you wont get a seamless patch either.

at a guess tyrolean finish.

 

[SCUDmcCOY]

1 part lime mixed with 1 part sandy loam.then soak it for 24 hours in horse urine after which it can be used for plastering.works every time.you should be able 2 get this at your local hardware.

 

[richee]

i think cutting a square will make it stand out more then just patching it.
also with such a small area, there is no point in using lime, and 5:1 for scratch and 6:1 for top coat. 4: 1 is too strong for external render