How much plasticiser / waterproofer?

[dabomb3k]

Been practicing and doing finishing plaster for a little while now, and going to tackle my first rendering job on my garage bricks..

Will clean and wash the area , apply pva the night before and then wet the wall before putting my render mix on,

I think I'm right in saying, my first mix should be 3:1 sand and cement?? But how much plasticiser and waterproofer should I mix in??

And what should the ratio of the second and final float coat be? Should I mix the proofer and plasticiser in every coat or just the initial??

Thanks very much in advance for any help

 

[roy c]

You don't put pva on brick work the night before !! You can hose it down before you render it and when you spread it don't let the water be running down the wall .You are aiming at getting the wall "damp" so it doesn't suck the life out of your render you can put a drop of w/proofer in your first mix (Instructions will be on the tub) I would put a 5-1 mix on for the scratch Measure everything out of the same container so you get equal mixes. For your top coat use a 5-1-1-mix (sand lime cement ) you don't need any additives in this mix (definetly not w/proofer if adding lime!!) if you want you could put a bit of plaz in but doesn't matter if you don't..

 

[dabomb3k]

Thanks Roy, I had some render work done before that I paid for and they put pva on the wall the night before so I just got that from them, no wonder it's already cracking!!

As for like, I'm not experienced with that at all so are there any alternatives? Would waterproofer hurt instead?

Thanks again for your help.

 

[roy c]

I am sorry but I don't understand what you are saying, I have told you what the process is .Do you mean another alternative to rendering?

 

[dabomb3k]

Sorry it's my stupid iphone autocorrect I meant as for lime. I have never used lime or know what product to buy? Is there an alternative

 

[roy c]

You don't have to put lime in the mix but it makes the mix pliable and helps to stop cracking and it makes a nice mix. You can just put w/proofer in your top coat instead or just plasticizer. Some of the lads put lime in the scratch as well but I usually just put w/proofer in it and lime in the top coat. Just practice on a small area on the garage till you feel like you have got it right and you are confident that you can do it.

 

[dabomb3k]

Okay Roy thanks very much for all your help,

last quick questions, do you have a particular make of lime that you use? Or which product/ where do you get it from?

Also my tub of waterproofer doesn't say how much to use? Do I put a lot in or just like a cup full?

Thanks again for all your help

 

[roy c]

The lime you have to use with cement is Hydrated lime (make sure it is Hydrated Lime) You should be able to get this from your building suppliers. I always ask them if they have any ripped bags as you find you wont need a large bag...But it does keep if you store it in a dry place. I have just done a little job and didn't need a bag of lime but the lads found a broken bag and I took what I wanted, But I needed a little bit of dry wall adhesive and there were no broken bags and I had to buy a whole bag for a few scoops full,, Swings and roundabouts Eh!!!Put your water in your mixer and add the w/proofer to that it is hard to tell someone how much as I just have a measured cup that I fill .Why don't you google it or one of the lads on here will tell you exact amounts..