You could try one of the smaller sorbus. For example Sorbus 'cardinal Royal'

http://www.growyourownfruit.org/epages/100054180.sf//en_GB/http/www.etracker.de/cnt.php/?ObjectPath=/Shops/100054180/Products/sor08

You need something that wont have too large a root ball

You'd be better off with a large shrub than a tree - most of the shielding from a tree will be 10 feet above ground, not at window level, and the root spread could be a problem that close to a house. Pittosporum 'Garnetii', Cotoneaster 'Cornubia' or 'Lacteus', Mahonia 'Charity', Prunus lusitanica 'variegata', Elaeagnus pungens 'maculata', Photinia fraserii are all evergreen and will all reach at least 10 feet or more.

27408. I strongly recommend Nandina. It's a shrub, so will give you privacy better than a tree, and grows to 6 ft with a 2 ft spread, is evergreen, and looks pretty all year round as the leaves change colour (to autumnal colours) whenever they feel like it. It also has red berries.