Can anyone explain why they need to build more houses?

Take money by force? When?

Do you seriously think that if a person owns a home and is not using it at the moment, that it should be made available as public housing? Millions of people own holiday homes etc., should they be handed over be used as public housing? How about cars, those of us who have spare vehicles, should we give them to people who don’t own cars? What about those who more wealth than they need to survive – should that be given away as well?

I don’t think that you are really giving it much thought. Private property is not for public use.

@DarkScribe No I do not. When a property is abandoned it is different. It is the same thing as throwing it in the trash. It is no longer property because there is no one for it to be property of. I don’t know how many of those properties are abandoned but the government sure does. They are auctioned off here.
An empty house falls down. Vandals destroy it as well as the weather. It will become trash if the owner does not maintain it. I suspect that the market over there for houses has too high a price on them. I also suspect that there is too high an overhead expense for the properties to be rented out and people don’t even need those houses because there are too many of them on the market.
I doubt that Britain has 4 million people living on the streets so there seems to be a lack of demand for new housing in that country. So I ask again. Why build more?
Also the governments over there are silly with their offer of 5 year leases take it or leave it. If it has not already started it will soon. Britain will have a currency devaluation in the next 5 years. I would not lease for more that 1 year. The governments are setting their desires way to high. No landlord thinks that they should make a profit on those houses at the landlords expense.
According to another question I just answered public housing tenants tear the places up anyway. The landlord probably figure that the elements and the vandals will do less damage and provide them with fewer headaches than the governments will.
I don’t know I am just speculating. So I am asking.

I could explain it, but I’d have to go through some serious reference work and it would take pages, maybe even a whole book. The short version is that there are a lot of complicating factors involved. One reason new housing has to be built is that there is often a mismatch between the vacant housing available and the needs of low income people. A large old home that is now vacant is going to be far too expensive to purchase and maintain as low income housing compared with something smaller. The other alternative might be to renovate the house into multiple units, but again the expense of this and long term maintenance issues may be greater than the cost of building new housing units. Even if there is no mismatch on the size of the housing units, the cost of acquiring the vacant property, renovating it to put it back into livable condition, and maintaining it long term are higher than the cost of building new housing. Other issues involve the ways in which funds for low income housing are allocated by the government. In the U.S. at least, and I expect in a post Thatcher Britain as well, tax incentives and favorable loans are much more politically popular than outright grants and these tax incentives generally favor new construction over use of existing housing.

@walterallenhaxton When a property is abandoned it is different. It is the same thing as throwing it in the trash

The likelihood of there being any real volume of abandoned houses is pretty well nil. Someone owns them, even in the case of an intestate death where the heir not aware of it.

@gussnarp It is cheaper to subdivide a house and make it into multiple units than it is to build an entirely new one. You do not have to buy many materials and you do not have to do it all at once. The main thing is to make sure that the shell is sound. The rest is a mater of thought and elbow grease. If financing is available for the purchase the remodeling work and materials should be a sufficient down payment. If it is not then the house is probably in very bad condition or in good enough condition to sell as is.
With a million vacant houses the price should not be too high. Something is encouraging people to think that those houses are worth more than they really are.

@walterallenhaxton Yes, something is encouraging people to think the houses are worth more than they really are. It’s called the market. Subdividing and renovating can be much more expensive if you are talking about an old home. It’s really not as simple as just throwing up some drywall. Modern construction methods make it very cheap to build new. There’s also something called obsolescence. Houses are only built to last about 20 years, then the maintenance begins to get very expensive, that’s part of why new is cheaper as well. Then there’s land, land is cheaper the farther you get from the city center, almost invariably. Existing homes are on pricier land, new homes can be built on cheap land.

You don’t have to accept my answer, but I don’t think this is the place for me to repeat an entire education in urban economic geography, so take it or leave it.

It hearkens back to the17th century and the natural rights philosophy that we are all born with the right to life liberty and property and those rights cannot be taken by the government without due process.

OK Fast forward to the mid 20th century-so times are good and Mr. Landlord buys property and rents it out for income to support his family. Since times are good property prices and rents are high woohoo. Then life happens.

There is a slight downturn in the economy and the tenant has to relocate. The property ts empty 2 months and Mr Landlord doesn’t have the money to spruce up the place so he has to let the property at a lower price. Over the next 15 years the maintenance and tenants become very sketchy. Finally after renting to a bunch of students the place is no longer habitable so Mr L puts it on the market where it goes unsold.

OR

In a high crime area many owners sell their homes cheaply to a developement company that plans to take advantage of a govt grant to renovate the neighborhood. The grants are cancelled when a new govt comes in and the bank funding collapses. The development company hires a management company to try to rent some of the homes until the economy gets better. Most remain empty.

OR

An old lady is living in 2 rooms of an old family home while the house falls into disrepair around her. When she dies her heirs are hit with a big tax bill and a house that they can’t sell or rent

There are lots of reasons for empty buildings.

After the properties remain empty, squatterss may move in. The properties might be stripped pf copper pipes and anything that can be sold for scrap. Windows get broken 7 roofs may leak and you end up with thousands of empty dwellings. The govement may want to come in and turn them into homes for the homeless but 1st they have to buy the buildings and then make them habitable and who’s going to pay for that?. Imagine trying to get the taxpayers to pay for decent apts for the homeless!