Attic used as grow room -- Is it safe?

I have been reading as much as possible in regards to growing indoors and trying to absorb whatever information that I have access to. I thought about using my closet but the confined area makes me think my potential yields will be pretty small, so I've been looking for a bigger area to operate within. I was in my attic the other day and it struck me, why not use this as my grow area! I have an area of my attic over my garage that is fairly large and has two different areas that look perfect for growing plants and cloning. One area has about ~7' clearance and the smaller area of the Garage attic has about 5' clearance.

However, I've recently become worried about something: Is it safe to grow my plants up there? I'm not so much concerned about the hassle of lugging materials up there or anything of that like, I'm moreso worried about the humidity destroying the wood that makes up my house. Is growing marijuana there going to promote mold growth that will cause me thousands in repairs? Or am I just parrinoid? Also, am I going to be more prone to fires than any other areas in my house?

 

I live in Jersey so the temperature varies, I figured I could use a small space heater during the winter to keep it warm and a small air conditioner during the summer to keep it cool.

Thanks for the fast responses!