It's pretty difficult to build a residential wind turbine which works at any reasonable efficiency.

One big point is do NOT attach one to your house, unless you have a proper survey done.
The vibrations from them can do serious to the structure, and can also cause a lot of disturbance.

Far better is a stand alone turbine, for two reasons: they obviously avoid the structural problems mentioned above and the further they are from the house the less disturbance, but they can also be built higher.
Wind has a surface effect, so the higher the better, as you get a lot more power.
They don't build those 80 meter high towers for the fun of it - they are far more efficient.

Some of those roof-top jobs get as little as 4% or so of rated power on average.

Home-built wind can work out in rural areas, where you can put a dedicated wind turbine at a good height and distance from your house, and particularly where grid electricity is not available.
Backup will still cost you a lot of money though.

So first ask yourself an obvious question, which surprisingly many do not seem to ask:'Is it consistently windy where I live?'