Here's something to cause a stir...this is what's on my own house:
http://cool386.tripod.com/digital/gore1s.jpgDespite the enormous size of the VHF aerial (3m boom length) it only weighs about 3kg. The UHF aerial above weighs less.
It's been up for about 14 years and despite strong winds, sometimes more than 100km/h, there's only a slight lean in the mast. One piece of advice I was given long ago was never to use water pipe for a mast with a chimney mount...the reason being that water pipe has no flexibility and transfers any stresses in high winds straight to the chimney. Gal tubing or proper aerial mast being of thinner walled construction bends slightly and absorbs the energy. It's important that the aerial mount is the weak point; not the chimney.
Chimney mounts have always been very popular here but it really depends on what kind of chimney is used, and what is attached to them, as to whether they are a good or bad thing.
I can't see the chimney in the pic at the start of the thread being under any stress given the small aerial and short mast. However, the particular mount does look flimsy.
One really bodgie installation I worked on was a 20 foot guyed mast. The guy wires had simply been passed through holes drilled in the tiles and wrapped around the timber beneath. Not a screw eye to be seen.
