External Render Questions
Discussion
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!
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!
Plastic or stainless for the corner beads (should'av been tacked on to start with) and another 8/10mm coat of render will be fine.
Go easy if using Feb, there's enough plastiser in the waterproofer. screed off with a prepared length of timber and fill any low spots and repeat. Float up and finish with a stiff/new sponge. Keep an eye on the render along the bellcast, it tends to collect the water and dry slower than the rest of the render. Keep the mix the same as the scratch coat.
Go easy if using Feb, there's enough plastiser in the waterproofer. screed off with a prepared length of timber and fill any low spots and repeat. Float up and finish with a stiff/new sponge. Keep an eye on the render along the bellcast, it tends to collect the water and dry slower than the rest of the render. Keep the mix the same as the scratch coat.
Spudler said:
Plastic or stainless for the corner beads (should'av been tacked on to start with) and another 8/10mm coat of render will be fine.
Go easy if using Feb, there's enough plastiser in the waterproofer. screed off with a prepared length of timber and fill any low spots and repeat. Float up and finish with a stiff/new sponge. Keep an eye on the render along the bellcast, it tends to collect the water and dry slower than the rest of the render. Keep the mix the same as the scratch coat.
Is rendering your trade Spudler?Go easy if using Feb, there's enough plastiser in the waterproofer. screed off with a prepared length of timber and fill any low spots and repeat. Float up and finish with a stiff/new sponge. Keep an eye on the render along the bellcast, it tends to collect the water and dry slower than the rest of the render. Keep the mix the same as the scratch coat.
Spud,
''Keep the mix the same as the scratch coat''
I have only done a fraction of what you have, but I was taught to use a weaker mix for the top coat.
Was told that this helps the wall to accommodate movement, preventing cracking.
I'm about to render a small garage extention so would welcome any other views!
''Keep the mix the same as the scratch coat''
I have only done a fraction of what you have, but I was taught to use a weaker mix for the top coat.
Was told that this helps the wall to accommodate movement, preventing cracking.
I'm about to render a small garage extention so would welcome any other views!
Spud,
''Keep the mix the same as the scratch coat''
I have only done a fraction of what you have, but I was taught to use a weaker mix for the top coat.
Was told that this helps the wall to accommodate movement, preventing cracking.
I'm about to render a small garage extention so would welcome any other views!
''Keep the mix the same as the scratch coat''
I have only done a fraction of what you have, but I was taught to use a weaker mix for the top coat.
Was told that this helps the wall to accommodate movement, preventing cracking.
I'm about to render a small garage extention so would welcome any other views!
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff