Rendering an extension

[Ruzzle]

I am now coming to the conclusion of a complete house renovation and have just an extension to render and then paint. The extension was built before I moved in and is constructed in an external skin of concrete brick. The internal skin is block work and it is cavity filled.

My proposal is to use a 3:1 10mm scratch coat using grit sand and opc after using a watered down PVA mix to dampen the wall.

Top coat (3-4mm)I was going to use 5:1 using grit and building sand and a waterproofing agent.

Does this sound about right?? Do I need to throw any lime in either of these mixes as a few posts mention it?

With regards to beadings etc, stainless, galv or plastic??

[thedoctor]

See our project on mortar mixes. Your mixes will work but we always suggest the use of lime. Galvanise beads are fine

[Ross Boseley]

Hi mate, Your best bet is to use a mix of 4:1 sand and cement with a capful of plasterciser and a capful of water proofer in each mix. You can add lime if you like it does make it easier to use just a shovel full in each mix should be enoguh. If you have external corners to get around you should use angle beads which you should stick on with your scratch coat leave enough room for your top coat. You should use either a stop bead or a bell bead at the bottom of your wall depending on what finnish you want. if you want to learn practically before you attempt it go to our project on plastering.