I have a small hand wash basin ready to be finally fitted. I have it just fitted onto its studs at the moment and is sags slightly from back to front. Possibly due to plasterboard being a bit distorted by previous wash basin. I have injected Pink Grip into the space between the plasterboard and the breeze block now.
I was considering applying silicone to the back of the basin - tightening it to the wall whilst wedging it level. However, I guess this could make future removal a problem and was wondering about using plaster. Apply a few dobs - tighten it whilst it is wedged level and wait for it to set. Then seal around edge with silicone.
What are your thoughts?