Re: Rendering a cellar

[Mr PGB]

Hi, Could anyone help me please, I want to render a sand stone internal cellar wall (12inch thick)can you or do you need to use a stabilising solution (yes there is efflorescence) and then a mortar based water proofer.
I use the cellar as a woodworking workshop, it is well ventilated there is an input fan and a blower fan...
The all the walls were previously coated with some sort of bitumen and then painted (before us), and this is the only wall with a problem, it has blown in some places 30% ish, which I have stripped back to stone with a large wire cup brush on my angle grinder, What would be the best way to proceed,
Any advice would be helpful. Thank you!!

 

[Kingfisher20]

Having removed all traces of bitumen, you need to firstly treat the surface with an "anti-sulphate" solution to neutralise the groundwater chlorides. Typically you would treat with "anti-sulphate" dilute 50:50 with water and the following morning before applying a polymer modified render, you apply the "anti-sulphate" neat by spray or brush. This forms the basis of any effective cementitious under ground waterproofing system.