The high cost of housing is a big problem for a lot of people. Younger adults in particular often can't afford to own their own homes like their parents did, despite earning similar wages corrected for (non-housing) inflation. Many of those who do own have huge mortgages that will take the majority of their careers to pay off, and face having to move should they suffer a significant drop in income. Many of those who can't own are priced out of the cities and regions they'd prefer to live in by spiraling rents and may face long commutes to work in those places.
What could be done about this? Well, one idea that keeps bouncing around my head is eliminating a situation which is quite rare and very unfortunate when it does occur - the foreclosure. If mortgage lenders lose the ability to take away the homes of borrowers who stop paying their mortgages, they'll stop lending people money to buy homes. This wouldn't be like a medieval anti-usury law - people would still be able to borrow and lend money with interest, it's just that people would no longer be able to secure those loans with their homes (because they need those homes for living in).
Wait a minute, though, doesn't that sound like it would make homes less affordable rather than more? Well, perhaps at first. But why are house prices so high in the first place? They're as high as there are because that's what people are prepared to pay. And they're only able to pay that much for houses because that's what lenders will lend them. So, in the presence of mortgage lenders (and absent any other restrictions) house prices will trend upwards until the cost of servicing a mortgage is equal to all the money that can be earned by the people living in that house minus what it costs them to live (food and utility bills). Rents will rise similarly, as otherwise it would make more sense for those who would buy property to rent to instead buy mortgage notes.
If this were to come to pass, what would the consequences be? Who would be the winners and who would be the losers? Well, anyone who owns their home or a rental property free and clear (or who owes less on their mortgage than the value of the property would decrease by) would suffer sudden drop in overall wealth, as would anyone who has invested in mortgage notes. However, most property owners with an income would suddenly find that a lot more of it would be disposable (no point making any more mortgage payments!) so there would be a massive influx of cash into the economy. Pretty much everyone but the aforementioned owners and investors would be better off. In other words, it would be a massive redistribution of wealth from the rich to the poor.
What about those who do not own their own property but instead rent? Most such people probably don't have large amounts of savings, so wouldn't be able to buy a house outright even at the new lower prices (if they could they would probably have enough for a mortgage down-payment under the current rules). So they will have to continue to rent. Since there's no money in mortgage notes anymore, buying rental properties becomes a relatively more lucrative investment. So those with the money to do so buy up all the (newly cheap) properties for rental. This (combined with the lack of mortgages), prices would-be homeowners out of the market again and forcing them to continue renting. New builds become less lucrative (since they can't be sold for as much) so the supply of housing goes down, which drives up rents to the limits of what the market can bear. So while getting rid of mortgages would help most current homeowners, everyone else would be screwed in the slightly longer term. Our little "tweak" has actually had the opposite of the desired effect! Not only is housing as expensive as ever, even more people are renting instead of owning.
We can fix this with another small adjustment to the rules - instead of just getting rid of foreclosures, get rid of evictions altogether. Everyone who is renting their home becomes the de-facto owner of that property. Sorry to the rental property owners, you're screwed right along with the mortgage note owners.
How would this work in practice? You can't evict someone from their home, but how do you define what "home" is for the purpose of this law? What if someone has multiple houses? I think my preferred implementation would probably be something like this: each person would be permitted to enter into a particular database a single address, which is the place that they are not allowed to be evicted from (their home address). People who don't like being in government databases don't have to be in this one, but would lose the benefit of having a home that they can't be evicted from. At the point of implementation of the law, you must have some claim on an address (i.e. ownership, rental agreement, or be a dependent of someone with an ownership or rental agreement, or have some reasonable evidence of occupancy) in order to make it your home. There would probably have to be quite a bit of wrangling and untangling to determine who should really have the right to live where. However, once the implementation is complete things become much simpler. From that point on, you'd only be permitted to change your home address to a new one with the permission (by power of attorney if necessary) of all living people who also claim that new address as home. This means that an inhabitable property that doesn't have anybody claiming it as their home could be claimed by anyone - a sort of "squatter's right" for this new regime.
Buying and selling property would be fine, as would any other contracts involving a change of home, with the limitation that at every point in the execution of a contract, every person has a home. So a new rental agreement or mortgage agreement would not be possible because there is a point in the execution of those contracts (i.e. non-payment of rent or mortgage) in which someone ends up without a home. Now in this form there is something very similar to a mortgage contract, namely "if you don't pay your mortgage, you have to change your home to this hovel in the middle of nowhere". It's a de facto eviction if not a de jure one. So, I think contracts involving home changes would have to not extend over time - they would have to specify a single point in time at which point all the home changes happen, and a home for every person involved afterwards. If one of those addresses turns out not to exist, then the entire contract would be void and everything would have to be put back the way it was at the start. If a contract did extend over time, the "hovel in the middle of nowhere" might turn out not to exist, and if too much time has passed then restoring the conditions at the start of the contract may also be impossible.
So in this world the concept of a chain becomes more important when buying and selling property. Every non-circular chain must begin with the splitting of a household or the destruction of an address, and end with the joining of households into a single address or the construction of a new address. "Construction" and "destruction" here do not necessarily mean physical housebuilding and demolition - it could be doing up a previously uninhabitable property or a previously habitable property falling into disrepair - both with the consequent changes to the "home" database.
The existence of "uninhabitable" property not listed in the "home" database presents a potential problem - a "shadow economy" of people living in "uninhabitable" properties with mortgages or rental agreements and all the accompanying baggage, with their "home" addresses (if any) pointing at some undesirable location. Perhaps this could be solved by forbidding people from living in addresses not in the "home" database and/or forcing property that is found to actually be inhabitable into the database. Forcing real estate to be in a database seems less onerous than forcing people who don't want to be in a database to be in one, but people not in the database may find it difficult to find housing if non-database housing is off limits. They'd have to live with somebody who is in the database.
Sometimes houses burn down, or the people living in them have a baby that there isn't room for, or a housemate turns out to be abusive, or any one of many other circumstances in which the supply of housing is insufficient for the people needing it. For these circumstances I think a basic minimum standard of social housing would be a necessary fallback when there's nowhere else to go. As a general rule people would not be expected to live in this high-density, no-frills accommodation indefinitely - it's just a stopgap measure until they can accumulate enough cash to buy their own property. It needs to be sufficient so that people living there can hold down a job (good night's sleep, sufficient facilities to remain clean and fed, no worrying about security) but doesn't need to be fancier than that.
A little care would need to be taken in the areas of hotel rooms, holiday lets and other short-term accommodation. Perhaps these things can be handled by saying something like "if someone stays somewhere for more than 183 nights in a given calendar year, that place is deemed inhabitable and can be claimed as home by that person", but we'd still need some way to allow people to go on holiday without making it possible for property owners to exploit the poor by making them rent and move every 4 months. There are other rough edges as well (what about people moving internationally?) but I'm confident these could be solved.
This all seems so sensible to me. It's too bad there's no apparent way to get from the grossly unjust system we have at the moment to this one - there are just too many powerful people who would stand to lose so much money that they would do everything they could to oppose it.