The containers I put them in are about 2ft in diameter. When they get too large I will either cut them back or give them to somebody to permanently plant them; I know a couple of friends & family who might want them. But, yes they do grow large and would not be suitable for planting near a house due to their massive roots. Thought about selling on ebay but with them being very common they are worthless.
My dad had a cedar tree given to him 20 years ago which was about 6 inch tall. It is now at least 50ft with a trunk about a foot wide. Just shows how big they can get in such a short time.
I don't have a garden, just a paved area so everything is in pots. The only things I bought were dwarf spruces that don't grow tall and are suited to containers. They should grow to a nice size to offer a bit of privacy without being too imposing. I had a lot of plants given to me when my stepmother moved in with my dad - I have only just got round to trying to identify what they are as gardening is kinda not my thing. These ash trees were some of the ones given to me. She said my yard needed sprucing up...
When I bought the house I wasn't bothered about buying nice plants to put outside mainly because I live on the outskirts of Bradford (a really crappy, crime ridden cess pit of a city) and it's highly probable somebody would steal them.
BTW if you google Bradford it sounds like a nice place to visit. Well the surrounding villages and countryside are nice; pretty much anything within a 3 mile radius of city centre isn't. Here's a funny link that accuratley describes what it's really like (don't click if you are easilly offended) http://www.chavtowns.co.uk/2010/06/bradford-where-do-i-start/