Passive RFID door lock penetration from inside

I'm looking to buy one of those RFID door lock kits for arduino. My question is, can the scanner detect a tag if its behind the door? What is the distance which the magnetic field of the scanner can penetrate wood?

I ask because all the examples I've seen have the scanner outside the door going through a hole in the wall and I would rather that it isn't noticable.

I used my RFID for the first time last night and found that the tag/card had to be no more than about 1cm away and that was in free air. When unlocking doors and parking booms at work over the years, I've noticed that more often than not, the card almost has to touch the reader pad.