Interlocking curtain wall insulation system

1. An interlocking curtain wall insulation system for a building, comprising:

a backer bar spaced from a floor slab defining a perimeter void between said floor slab and an outer wall;

a safing insulation disposed above the backer bar and compression fit within said perimeter void between said floor slab and said backer bar;

a first curtain wall insulation extending from an upper surface of said safing insulation adjacent said backer bar to a first insulation hanger; and

a second curtain wall insulation depending from said backer bar and connected to a second insulation hanger;

said safing insulation further fixed between at least one of said first and second curtain wall insulations and said backer bar.

2. The interlocking curtain wall insulation system of claim 1 , further comprising at least one curtain wall insulation hanger compression fit against an upwardly facing surface of said backer bar.

3. The interlocking curtain wall insulation system of claim 2 , said at least one curtain wall insulation hanger bar having at least one leg for impaling said second curtain wall.

4. The interlocking curtain wall insulation system of claim 1 , further comprising a backer bar hanger affixed to vertical supports and supporting ends of said backer bar in a horizontal orientation.

5. The interlocking curtain wall insulation system of claim 1 , said backer bar being substantially T-shaped.

6. The interlocking curtain wall insulation system of claim 5 , said backer bar having a first vertically extending leg, a second vertically extending leg, and a third substantially horizontal leg.

7. The interlocking curtain wall insulation system of claim 1 , further comprising a safing clip engaging said slab at a first end and impaling said safing insulation at a second end.

8. An interlocking curtain wall insulation system, comprising:

a backer bar spaced from a floor slab and defining a void therebetween;

an upper insulation hanger disposed above said backer bar;

a safing insulation disposed within said void between said backer bar and said floor slab;

a first insulation curtain wall and depending from said upper insulation hanger and engaging an upper surface of said safing insulation;

a second insulation hanger positioned adjacent said backer bar and engaging a surface of said safing insulation; and,

a second insulation curtain wall disposed between said second insulation hanger and said backer bar;

said safing insulation being fixed with respect to two planes.

9. The interlocking curtain wall insulation system of claim 8 , said safing insulation formed of a single piece of insulation.

10. The interlocking curtain wall insulation system of claim 8 , said safing insulation formed of two pieces of insulation.

11. An interlocking curtain wall insulation system, comprising:

a first insulation hanger;

a backer bar disposed beneath said first insulation hanger;

a second insulation hanger depending from said backer bar;

a safing insulation disposed between a floor slab and said backer bar;

said safing insulation further disposed between one of first and second insulation curtain walls and said backer bar;

said safing insulation causing frictional engagement and interlocking of said second insulation hanger.

12. The interlocking curtain wall insulation system of claim 11 , said safing insulation being oversized with respect to a gap between said floor slab and said backer bar.

13. The interlocking curtain wall insulation system of claim 11 , said safing insulation fixed in a vertical and a horizontal direction.

14. The interlocking curtain wall insulation system of claim 11 wherein at least a portion of said safing insulation is compressed to inhibit fire and smoke from passing between said floor slab and said backer bar.