How to fill inbetween chipboard and existing floor boards

[Ashworth1]

Unfortunately I can't bring my chipboard over to sit on the existing joists as the bricks in certain parts are too high. I don't want to do any grinding/knocking about as the new joists are chemical bolted to those bricks.
What would you advise to fill to level the chipboard/floor boards together? Was going to use sharp sand and cement but may crack as it will only be about 15 mm in places ? Any suggestions? Thanks

 

[oldbutnotdead]

If you are carpeting or putting laminate down then sand/cement would probably be OK. Other option is half inch ply (or half inch timber if you can get any wide enough)- either cut it to the shape of the floorboards or square that side up, if the top of the brick wall is fairly level then shim it every 150mm, drill, plug, screw. If the top of the bricks is off then thin mortar bed, drill, plug, screw (put mortar down, bit of polythene on it then squidge board on top til it is flush, let mortar go off, drill, plug, screw)