Thin render - one or two coats?

[nafuk]

Hi, I have an extension built of thermalite blocks butting up to my original house. The original part has a thin render coat, approximately 1-2 cm thick. Should I render the extension with a scratch and top coat or one single coat? Any other tips gratefully received. Thank you

[John Rumm]

Sounds like two coats would be easier. Use the scratch to try to leave an even thickness for the finish coat. It does depend a bit on what sort of finish you are after. If you just want rough cast[1] then you could texture a single scratch coat and be done with it.

[1] note there seems to be a huge regional variation in what people think of as rough cast.