Rendering and plastering with Sika 1

[tahirh]

Hi,

I have just injected DPC into my kitchen walls and now plan to sand and cement render all the walls. I am going to be adding Sika 1 to the mix to prevent any moisture from coming through.

What I need to know is if one layer of render is sufficient and how thick should it be?

Can I then plaster straight over the render?

 

[marshman]

No, you need to scratch coat the walls and at least let the scratch coat pull in, ( hardened) before you put your float coat over it.
You need to kill the suction with the scratch coat so your float coat cure / dry slowly, you can leave your scratch coat for days before
you do your float coat but you should damp your scratch coat if you let it dry right out, don't trowel your scratch coat smooth it needs an open
face.
A scratch coat is a lining coat of render that is used to level up the walls and to hold back suction, and you scratch wavey lines
across its face but not right through and about 2 inches apart.