Mike,
Do your orders say you are authorized 30 days of leave? If so, they can't say a word about it. You are entitled by your orders. Additionally, you get travel and proceed in ADDITION to your authorized leave. House Hunting is generally separate from your transfer, usually a few weeks or more before you actually transfer. I would suggest the same as Kirk, ask for house hunting leave. Besides, its free leave! And now you can carry 75 days over the fiscal year vice the previous amount of 60. Just my $.02