I have hacked all the old plater off in my house, in side as it was loose and all cracked.
What i need to know is, how many coats will it need?
I want the finial coat to be skimmed as i want smooth painted walls?
Any advice will be good.
Right o mate you only need one coat of backing plaster and a skim coat on the top. If you want my advice though mate on old walls i'd dot and dab as you'll find that your backing plaster will dry a bit quick. You'd still only need a skim coat over the top of your bards but if it's your first attempt it will be a lot easier.
Basically mate theres bagged backing plaster that you can get now thats just as good as sand and cement i'd personally use tough coat or hard wall you can get it from any builders merchant. If you still insist on using sand and cement then i'd use a mix of 4:1 make sure you add plasterciser to each mix you can add a shovel of hydrated lime to each mix if you like it does make it easier to use but if you get it on your skin it can really give a good burn so make sure you cover up properly. on old walls you should skim your walls the same day as you float them because like i said it's gonna dry fast.
Good luck mate if you need any more help feel free to ask again