Skim coat over sand & cement backing coat

by Dylan
(Jersey)

I'm going to use sand and cement to cover the block walls in my garage.
From reading this guide it looks like i will be ok to apply a backing coat of about 15mm making sure I apply a thin well forced on initial thin backing coat.
Once I have finished the backing coat will I have a nice surface to paint or do I need a skim coat? If a skim coat is needed how does this adhere to the smooth finished backing coat?

Answer

If you manage to get a nice surface with the sand & cement that will be absolutely fine to paint. To help with this you can finish it thoroughly with the float so as to provide a smooth flat finish. If any areas dry too much then damp down with water as necessary. To get a smoother finish a sponge can be used by lightly smoothing the whole wall.

If you are planning to skim the sand & cement backing coat the float must have a nail protruding on the underside - this will scratch the surface and provide a key for the skim coat.