If you've came across an under flooring that's got more craters in it than the moon, Bostik Screedmaster SL C951 Deep will sort it out. If you're going thick, this is the one - as its formulated to dry quick, even if you're going deep.
It's a high strength, self levelling and resurfacing compound that can be applied more than once to level out a floor. Overtime the flooring will stay in perfect condition. Think happy subfloor - happy client.
Suitable over most substrates, including; concrete, sand/cement screeds, rigid metal, terrazzo, quarry tiles, unglazed ceramic tiles and other strong, rigid subfloors. And with features like walk on time 1.5 hours and it being pumpable, the job will be done in no time.
Not sure how many bags of Deep you'll need? Divide the m2 you want to cover by 12.1 and times the depth in mm. Screedmaster Deep can be laid 5mm to 50mm.