External Render Questions

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VxDuncan

Original Poster:

2,850 posts

236 months

Wednesday 21st September 2011
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Hi,
I'm building a garage at the end of the garden out of solid (dense) concrete blocks, and looking to render it. I've done a fair amount of plastering (three complete rooms), but rendering is a whole different ball game!

Current status is I've battened out (to 10mm) one side and put a scratch coat on to the depth of the battens. I had to use SBR to seal the walls and provide a better key, even though I'd had the hose on the blocks previously. The mix was 4:1 with a combined waterproofer / plasticiser added.

Now looking at do the top coat, aiming for a smooth finish. What thickness do people go for? I understand it should be thinner and weaker than the scratch? Currently thinking 5:1 mix and 6mm? Should I add waterproofer or just plasticiser?

Big thing is how to I get this level and do corners - Do I batten out again (to 6mm) and level off to them or do it freehand levelling off with a derby? I'm used to doing a 3mm skim with plaster, but 6-10mm is a bit scary! I'm also used to using angle beads inside, but they don't seem that popular outside (and are expensive), so I understand most people trowel off against a piece of wood (this is what I did for the scratch). There's a UPVC bellcast bead on the bottom.

Any advice or tips gratefully received!