Rendering on columns and beams

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Rendering on columns and beams

Postby thailazer » Fri Aug 26, 2011 7:58 pm

Noticed something odd today on a project. It seems that rendering on beams and columns is a two step process. First step is to build a concave corner on the edges, somewhat like a ski jump. The guy I saw took great care to bring it to a very straight point. The flat rendering happens a few day later. Does anyone have an idea why this is done this way in Thailand? I've seen rendering in the USA and it is a one step affair. Slap it on, make the surfaces flat and ensure 90 degree corners. What is up with the two-step method?

A few hours after the guy took off, I saw fine cracks in the ski-jumps he had put on. This probably due to mixing the batch of sand, cement, and water on the ground with no measurement of ratios.
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Re: Rendering on columns and beams

Postby geordie » Fri Aug 26, 2011 11:13 pm

first its a pain to get cement to stick to concrete so stage one the corners is done slowly giving something to bind to
secondly the cracking (hairline ) is normal the concrete if you wet it will not absorb so will definately not let the cement stick
third The top coat will be aplied wet and hopefully will dry without cracks

The other equally important explanation is simple in uk we set corners with metal angle beads which gives you a so;id grip on the corner and a level to work too i am assuming in the states they do the same but the thais do not/ so at the mum in laws house one guy spent days literally building corners on the walls which later became casualty,s to furniture being bounced of them

Of course he could have used the wrong grade of cement which caused it to crack as well :lol:
my comments may be wrong but never deliberately
If it aint broke, dont fix it
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Re: Rendering on columns and beams

Postby thailazer » Sat Aug 27, 2011 9:17 am

Thanks G! It's interesting watching the different techniques here, and there is sometimes a good reason. The guy doing the corners sure was into is job. Total concentration and almost "Zen-like" every time I stopped by to see what he was doing.
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