Rendering Exterior Walls mix of breeze and thermolite

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Crooksey

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I'll start by saying im not a professional renderer, just a bloke who does a lot of skimming and internal rendering for my own customers/friends, id say its about 60% of what I do, but im not a full blown plasterer.


Im doing a job for a mate of mine this weekend, thats going to be external rendering on a breeze block/thermolite mix wall (yes i know before you start lol) conservatory.


Ive never done large exterior rendering jobs before, usually just patches here and there to help a mate out, but ive done a fiar amount of internal stuff.


My couple of questions are:


1. If there are a few light showers over the weekend, will it cause me any great problems?


2. I take it I can just give the blocks a very light soaking, then render straight on, do I need to even soak them?
Trying todo it as cheap as possible for him, so dont really want to sbr slurry it


3. Was going to scatch coat saturday, then top coat sunday, or is that too soon?


Mix wise I was going to use 5:1 both coats, with waterpoofer in the scatch and plasticiser in the top coat, sound good?


Plastering sand of course as well, none of this rubbish rendering with building sand!
 
use 4 and 1 for scratch coat and definetly waterproofer,
with mix block work tend to use sbr and cement slurry before scratch to neutralise suction, ie one section drying before the other.
 
Will it cause me any problems if the sbr dries before I get to it, as i take it even though its dried, it will still stop a lot of the suction?


So I could fully coat the walls in the sbr/cement mix, let it dry, then render on top?


Or is it best to keep applying it as I go down the wall, always going on when its tacky? As im guessing they are going to soak it up like a camel in the sun.
 
Dansouthcoast84 said:
brush or roll it and key it if you are going to let it dry.eg. leave a stipple or scratch comb
Click to expand...

As above but preferably wet gobbo on wet sbr . 5:1 scratch with water proofer and slighter weaker second coat with febmix. Too strong a mix only a day apart could craze.

If you wet it down instead don't flood it, it will bleed at the horizontal joints unless you put plenty in the night before. But Thermalite isn't the best block to render onto. Let your mate know using thermalites for rendering is wrong or you might not be mates for much longer.
 
Have a look on the information guide mate should find what you want if not come back and ask:RpS_thumbup:
 
He wants it done as cheap as, so ive just said, look as a mate its your call. If you want to dampen them, it could crack, however with sbr there's a chance it could still crack, but alot less likely, so your call. Ill do whatever he wants at the end of the day, knowing that it could crack in places. Im also going to leave the top coat till the week after.
 
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