need advice on antenna masts
 

I'm having second thoughts about mounting an antenna mast on my roof or chimney.

I have a chimney that is about 14 feet high at the top. I'd like to get a mast I can set in concrete and then secure the upper end of the mast to the top of the chimney.

If I set the antenna in a post-hole 42-44" deep and about 10-12" wide, then secured it to the top of the chimney with lag bolts, how much higher could I go without having to use guy wires? I have a Digiwave 7287 8 bay antenna that is quite large and weighs about 10 pounds. I live south of Montreal. Lots of snow in winter, but no hurricanes.