Posted: 08/09/2016 at 13:32
Trees do lose some branches regularly as well. Perhaps you could get a couple of people to give you their opinions as to the lifespan of the tree. It may justneed some careful pruning.
However, if it has to be removed, I'm afraid it's the often asked question here: something quick growing that then stops. Unfortunately, it's not that simple. Anything which grows rapidly, won't just magically stop, and will therefore need pruning and trimming regularly. Things like the dreaded Lleylandii, which you've probably heard of, will keep growing indefinitely, at around 3 or 4 feet a year, and can cause all sorts of issues. Eucalyptus is another tree which grows rapidly - but keeps growing....
A single tree will take several years to make a big enough screen , unless you buy a mature specimen which will be very expensive.
You may be better considering a hedge. Even good old common privet will grow fairly rapidly and needs trimmed a couple of times a year to keep it tidy - more if you get a good bit of rain. Technically semi evergreen, but provides good cover. Laurel is another contender for rapid hedging, but takes up more room. Beech or Hornbeam aren't evergreen as such, but retain their foliage over winter and provide a decent screen.
Alternatively a couple of larger shrubs - some of the Viburnums are evergreen and will get to about 3 metres in each direction.
Hope that's a little help