# Forum Home Renovation Concreting  Specs for new bathroom floor over exisiting floor

## ascheer

Want to put a new concrete floor over an existing concrete floor in a small bathroom. The walls are brick. I've removed the tiles from the walls but I've not removed the floor tiles. 
New slab will be 180mm thick. Size of floor is 2400mm x 1100mm. 
1. What strength concrete? 
2. Do I need a damp proof membrane under the slab and up the wall? If yes, what type /quality. 
Do i need reinforcing mesh? If yes, what type/size? 
Many thanks, Andrew

----------


## Oldsaltoz

Mat I ask why you plan to raise the bathroom floor 180 mm? 
This might help to improve the quality of the answer.

----------


## ascheer

To make level with adjacent floor.

----------


## Oldsaltoz

> Want to put a new concrete floor over an existing concrete floor in a small bathroom. The walls are brick. I've removed the tiles from the walls but I've not removed the floor tiles. 
> New slab will be 180mm thick. Size of floor is 2400mm x 1100mm. 
> 1. What strength concrete?  I would think a 32 MPA maximum, but suspect less will be fine, a quick call to your local concrete supplier will confirm the required strength for your area. 
> 2. Do I need a damp proof membrane under the slab and up the wall? If yes, what type /quality.  I am confident you will need little or no such preparation with a slab that thick over an existing slab, I assume this is on the ground floor. 
> Do i need reinforcing mesh? If yes, what type/size?  'J' mesh about 10 mm bar should be fine, drill holes 300 mm apart 60 mm below the finished top and insert 10 mm bars long enough to sit the sheet of mesh on and stack a few bricks to support the mesh away form the walls about 750 mm spacing.  
> Many thanks, Andrew

  Also consider establishing falls for the floor and shower waste areas. 
Hope this helps.  :Wink:

----------


## ascheer

Thank you, much appreciate your help.
Regards, Andrew

----------

