replacing toilet

[steveh1300]

i want to replace my old toilet with a new close coupled cistern, the problem is that at presentthe waste comes up from floorboards between joists about 12 inches from wall is there a way round this , the only solution i can think of is to fit it and fill the gap between cistern and wall, (approx 5in) by boxing it up.
cheers steve

 

[seco services]

as you say batten and build a false wall