Patching External Rendering

[DirtryDick]

Part of the rendering on the external wall of my house has fallen off. Can someone tell me what the correct ratio of sand / cement is, and what knid of sand do I have to use, do I have to put any additives into the mix, do i patch using one or two coats?

Please be gentle as I am a newbie

Thanx

DD

 

[jbonding]

what kind of render finish is it?
why has it fell off?
sand and cement (rendering sand) 3-1 with waterproofer for scratch coat, 5-1-1 (lime) for top coat. It is imposible to match up rendering without noticing so might be worth taking it all off especially if some has already failed.