I need help filling a patch with hardwall

[bestdadcup]

I live in a old house and the 1" original plaster have blown in places so I drilled holes in the plaster and injected sbr to see if the plaster would stick back to the bricks but this was taking to long so I decided to knock a patch off and I wish I hadn't now as there's a 40mm deep void to fill under the window. I've bought a bag of hardwall but I don't know the best way of filling the patch so can someone help me with the question I have.
1. The patch is 3 foot by 2 foot and 1" thick so how many layers of plaster should I do to build up to 1".
2. How much water do I need to make enough plaster.
3. If I fill the void under the window sill with expanding foam will hardwall stick to it.
4. Before applying the hardwall do I soak the bricks with water or do I need to apply sbr or pva.

 

[Danny]

I live in a old house and the 1" original plaster have blown in places so I drilled holes in the plaster and injected sbr to see if the plaster would stick back to the bricks but this was taking to long so I decided to knock a patch off and I wish I hadn't now as there's a 40mm deep void to fill under the window. I've bought a bag of hardwall but I don't know the best way of filling the patch so can someone help me with the question I have.
1. The patch is 3 foot by 2 foot and 1" thick so how many layers of plaster should I do to build up to 1".
2. How much water do I need to make enough plaster.
3. If I fill the void under the window sill with expanding foam will hardwall stick to it.
4. Before applying the hardwall do I soak the bricks with water or do I need to apply sbr or pva.

Noticed that this has not been replied to so I may as well reply.

The instructions for hard wall are on the bag with regards to the amount of water you need.

At an inch think I would do it in 2 passes.

Depending on the suction those two coats could be done quite quick.

Don't fill anything with expanding foam...

Water should be be plenty on the bricks.... Measure you do around the edges and the exposed surrounding area