Better look for another landingsite.
There have been several accidents, where the downwash blew parts loose, i.e. roofpanels and so on.
The stuff isn´t build to withstand the downdraft of a helicopter.
You´re lucky, if only the helicopter breaks....
I remember a rescue BK117 crash 2005 in Germany
http://www.idowa.de/donau-post/nachr...redaktion_id=5
Parts from the wall were blown loose and went through the rotor - and the building was only to one side!!!!
Another accident happend only a few days ago
http://www.va-luftrettung.de/forum/s...ead.php?t=2107
So better look for an apropiate landing site and walk 200 meters - a doc might even be faster at the scene of action because a quick landing some meters away takes much less time than a very slow and cautious decent in a confined area - not regarding the crashrisk!
Fly save - greetings Flying Bull