I have concrete lintels over the windows in my house, no plaster on em, just the bare concrete. How do I drill into them tidily without a) buggering up the drill, or b) going too far and compromising the structural strength of the thing. How deep inside the concrete will the rebar be? (ie how deep a hole would I have to be drilling to get into trouble?) If I borrow a SDS drill will I be indanger of going too far in? I've got about 15 curtain poles to put up so I'd like to get it right (particularly not to have the house fall down or cracks to appear if I break the lintel - you can't do much with cracks in ff brickwork.)
Cheers.