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Im in the process of rendering an old house in monorex. We have scratched it in sand+cement with sbr and this scratch coat has been on for about a month. The other day we rendered part of the back without wetting down the scratch coat and although most of it went on fine we had a few areas that sagged on us. It all scraped back fine once we had sorted out the sagging.
My question is would we have been better wetting the scratch down fist ?
(the mono work is hand applied)
Sounds like it may have been put on to heavy , and we usually give it a fine spray depends on weather conditions
The problem with using sand/cement waterproofer instead of pre-rend is it can be too water tight and cause the said problem, at the top it is probs fine, then when you get lower you will get the water from the mix working it's way down the water tight scratch coat and causing the sagging prob (no suction)
monocouche renders require no wetting down at all at all at all......they are designed to go over perfectly dry blockwork or fully cured basecoats with no waterproofer. Any wetness or moisture resistance will throw a spanner in the works and cause you problems. Better to lay on in two passes with the first slightly wetter to kill the suction of the unwaterproofed basecoat, but hold nicely in place with no sagging then a thicker, dryer(but still nice and workable) coat over the top( thicker to avoid not breaking through to the first coat when scratching back and thus introducing a whole new world of nastyness). :)
ha ha i know wat you mean i got a bit carried away with my scratcher on some ocr managed to repair tho had me sweating tho :)
It has been left too long and the waterproofer has cured, its best to work on a scratchcoat with waterproofer the very next day.
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