Well its a bit of a long story.
We're forming a co-operative because we don't like the idea of a house being an asset. We don't care about how much the thing is worth in 10 years time - we just want somewhere to live. We'd be pretty committed to this idea regardless, but the current state of the housing market in the UK seems to be emphasising our point. House prices are too high. The reasons they are too high are numerous - we're a densely populated island, we have strict planning laws and a shortage of land. But the big one driving all of this is speculation. If a house is seen as an asset then its value as a useful item is irrelevant to how much it costs. People will keep on paying ridiculous prices for houses so long as they think that in the future somebody will pay even more. Though fortunately this may be finally changing.
So as well all of the other benefits of setting up a co-op, one really good ancillary effect is taking a house out of this crazy speculative market. This house will never need to be bought or sold again. It can go on being a housing co-op until its no longer a house. Plus, once the mortgage is paid off, the money made from rent can be used to buy more houses, to transform them from assets to homes. We like to think of it as a socially conscious, very slow revolution.
Now I'm going to take a bit of time out from talking politics, to tell you about Terry Pratchett. Terry Pratchett writes about the discworld, a semi-comic fantasy world where all the mythical creatures you can think of are real, and are looking for jobs. The golems of discworld however, are property. As virtually indestructable beings made of clay, from ancient times, their ownership has been passed on for far longer than anyone can remember. The golems for the most part seem to accept their lot in life, existing primarily to work. Then one day a man buys a golem, and gives that golem his own receipt.
After some initial ill-thought out destruction vested upon his former owner's business premises, the now free golem seeks employment. Seeing as he is a large clay statue, he has no need of his wages, and so saves them until he has raised enough to buy another golem, and another. Soon there are dozens of free golems, all working not for their own benefit, but to extend the freedom of their race. A truly socially conscious revolution. If they are property, what stops them from buying themselves out of the market?
Well, if it works for golems, why not for houses?