I got my dad this same house from Sears about 20 years ago or more.  He never had much luck attracting martins but he doesn't live hea water and it was mounted only about 10 ft high.  When I discovered that he'd taken it down I asked if I could have it.  We live on a lake and I set it up about 15 ft high right on the lake shore.  We've had occupants every year since.  The house feels lightweight but it is still in great shape after all these years.  I think the light weight is good because with the nests and birds inside that is more weight and the box sways a little in a heavy wind.