I believe the slope you're referring to is an architectural feature of the hangar intended to prevent heavy rain, for example, running into the hangar. The actual slope angle is probably given on the hangar drawings - if they are available. If not, and you really need to know, then you may have to look-up specs for a hangar - sorry, I've no idea where you'll find them!
Most light helicopters on skids have a clearance of about 1" - 1.5" when on the ground-handling wheels, keep the tyre pressures up - it's in the maintenance manual - to ensure this, a little higher pressure will be quite safe and help to ensure the helicopter does not bottom-out when moving in and out of the hangar. Don't get too concerned if the skid tubes run on the concrete for a meter or so, they're designed to do this. Hope this helps.