waterproofer additive

[tiger]

planning on rendering exterior wall with sand/cement/ hydrated lime 4-1-1 scratchcoat and 5-1-1 top coat, wondering if it is usual practice to include a waterproofer additive in one or both coats.
appreciate any advise.

 

[Nisus]

In 1st coat mate & leave out the lime.

 

[craigw]

why do some people put lime in the scratch coat,who has taught them that? internal sand lime fair enough,but i have never heard of it in a external scratch coat,it would make your top coat suck like a ******* bitch.

 

[spark2010]

Depends on the background and suction... normally 5-1 / 4-1 (with feb and waterproofer), and top 5-1-1 / 6-1-1 (lime without the admixtures). Apparently mixing lime and waterproofer isn't advisable. think about it.. the reason for waterproofer is to equalise the suction on the scratch for the top coat. Some people put waterproofer in both coats. You dont have to use lime in the top coat either. But you got to let the scratch coat dry out properly so the waterproofer can do its job before applying a top coat.

 

[beddy]

ive only ever used waterproofer in both coats once, never again. it was a long long day of doing fucck all

 

[henry]

I will ask you a question what did we use before waterproofer in scratch coat. And why do we put it in our mixes now , well on breeze I can see a point to it but on brick why. Just how much moisture ,rain will render soak up before it is onto the brickwork . I will tell you what I have seen of late is blown render due this warm spell .

 

[martinemj]

when rendering over stone you would have lime in the scratch too

----too strong a mix otherwise...

 

[lucius]

I will ask you a question what did we use before waterproofer in scratch coat. And why do we put it in our mixes now , well on breeze I can see a point to it but on brick why. Just how much moisture ,rain will render soak up before it is onto the brickwork . I will tell you what I have seen of late is blown render due this warm spell .

Water:RpS_biggrin: