[villagetinker]

If you have or can borrow a stud finder, you can try to hit the stud (aka furring strip) for additional support.

I have put up curtain rods on all of the windows on our block house with no problems, just used the normal plastic expanding drywall hangers. I have also hung several pictures on outside walls with one problems. The above poster is correct about the 1" space (it is actually filled with solid foam type insulation between the furring strips.

If you are putting up something heavy (like a wall mount TV), absolutely goes for the studs, if you cannot hit these, then you can use a concrete drill and the appropriate expanding bolt. I have done this in the garage and hung ladders, tools, etc on the walls.

As an aside, you can get your house plans from the building department or online (do a search on this site for specific instructions), and this will have details on inside and outside wall construction.

Hope this helps.