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Depth of sand/cement over blocks?

I am blocking up a small window today. It's about 2 by 3 feet and I have some 'lite' blocks to do it.

The outside wall is rendered and painted so I need to get the finish as flush as possible.

Can anyone tell me roughly what depth I should be looking to leave for the sand/cement skim I will cover the blocks with. Obviously, too thin and it is likely to just fall off but too thick and the mortar may slump.

Any other tips? Other than pushing some newspaper down the cavity to catch the mortar drops on the inside.

Thank you. Rob

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Reply to
Kalico
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I'm no plasterer but the last one I did I left 3/8" and sealed the blocks with pva. The mortar was a bit reluctant to hang on at first but bonded very well in the end with no cracking. Getting that final finish to match the texture of the surrounding wall is a skill that still eludes me.

Reply to
Stuart Noble
[snip]

Yes I know what you mean about tying to match the texture, but in this case I am not too worried about it. I'm leaving the soildier bricks in place so it will be pretty clear that there was a window there anyway.

Who knows, someone may want to open it up again in the future.

Thanks for the tip on depth though.

Rob

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Reply to
Kalico

Either make it the same as the rest, or go for 1/2" (your blockwork may not be exactly flat, don't forget). Damp the blocks and apply your render, when it's gone off for a while and is setting, level it off with a 2x1 planed batten (slide it from side to side as you pull it up from the bottom of the blockwork), make good any hollows. Remove mortar that's been transferred to the existing surface.

What is the original surface finish? What is the existing mortar made of?

Reply to
Chris Bacon

On Fri, 14 Oct 2005 12:58:58 +0100, Chris Bacon wrote: [snip]

The original surface is, I presume, sand and cement. It's on a 1930s standard semi and painted over.

I had planned to use 5:1:1 sand:cement:lime. Sound about right?

Rob

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Reply to
Kalico

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