There a a few various tips and tricks you can do to help yourself out in cold weather rendering it starts with making sure there is guttering and temporally down pipes in place your problems could start a couple of days before you turn up to topcoat if the walls have taken a good soaking also if you can and there is scaffolding involved and if its safe remove the boards nearest the wall so the rain cannot slash up on to your wall again soaking it , make sure you fill the beads out that little bit more when applying the scratch so your topcoat thickness can stay around 8mm or under also cut down on the amount of waterproof that goes in the scratch especially towards the bottom half of the wall as madmonk said above the water drains downwards so maybe use a 1/4 of your normal amount or leave it out all together .When topcoating make sure your sand is dry and been keep covered ,why not start from the bottom of the wall so the bit that hangs around the most goes on first try to stiffen the muck up a bit by cutting the water down make it slightly harder to use but again it will save you time , use twice as much lime in the topcoat as you would normally , stick on old newspaper to just above your bellcast this will pull out water from the render changing it once it becomes saturated . Use a frostproofer/accelerator in the mix and use a bit more than the stated dose and make sure you have cut off time for when stop putting the render on the wall 10.30 am works for me you can get a fair bit on by then also the temperatures start to drop after midday .
