This might be a silly question but what is the reason to use somthing like balls 1100 over a new anhydrite screed the finish on its really good and flat
Not all are finished to a good quality. Just like you can get a perfect finish on concrete, most are poor.
Because it's a gypsum based product going on top of a gypsum based slab. They're more compatible with each other rather than a concrete slab. It smoothes the floor off not levels it like when people say self levelling it's not, its only self smoothing otherwise you would mix a load of buckets throw them down go back the next day and it's flat and perfectly level.
you use 1100 as its calcium sulphate based like the anhydrite, Would you go over a powerfloated floor even if it was shiney and smooth? same principle put down your own prep to get it to your standard and meet manufacturers guidlines, there is a technical reason why you shouldnt stick straight to it but off the top of my head I cant think of it, a builder I used to do work for stuck a 15k solid wood floor down direct to anhydrite over ufh which I advised against, last time I drove past that house he was still there a month ago and he was meant to be out in june/july im guessing something went wrong.
After having a read, 300 HD and P131 are good for anhydrite. Think it was a lack of grinding or incorrect primer ratio??
This was only single coat primer no grinding ,damp , was underground at the bottom of a large hill with recent heavy rainfall plus half the building still open to the elements Was a one off build grand designs stuff They was loads that contributed I think
Customer wasn't interested in anything other than getting something on the floor so I told her I'm not interested think original fitter went back I think
