Media playback is unsupported on your device Media caption Tens of thousands of people are believed to live in illegal rooftop slums in Hong Kong

Fifty-eight-year-old Hong Kong resident Chan Piu sleeps on a pile of newspapers on the floor because there is no space in his home for a bed.

He lives in a windowless room that is no larger than a parking space, and standing there, even for a few minutes, feels claustrophobic.

A picture of his late father hangs on the wall, watching over him silently.

It is a cramped existence, made even more so by the fact that seven other families share the same kitchen, toilet and small living area.

But when you step outside Mr Chan's room and exit the narrow hallway, you are greeted with a stunning view of the sprawling city below.

It is a penthouse view, but one that is only available to the poor.

Mr Chan and his neighbours are among Hong Kong's thousands of rooftop slum dwellers, pushed to the top of old apartment buildings because they cannot afford the spaces below.

Image caption Mr Chan sleeps on a pillow and a pile of newspapers in the corner of his tiny room

Image caption The 58-year-old has been waiting two years to get public housing

Image caption The entry to Mr Chan's rooftop house

These shacks are usually made of cheap metal sheeting and wood, with the interiors partitioned to hold multiple people or families.

During the summer the shacks get stiflingly hot, and in the winter bitterly cold.

Rooftop dwellers

By some estimates, Hong Kong is the world's most expensive property market.

Residential prices here have more than doubled since 2009 and despite a series of cooling measures, some experts believe prices may continue to climb even further.

Image caption Rooftop slums, or "penthouse slums", are illegal in Hong Kong

In Hong Kong's working-class neighbourhood of Sham Shui Po in the Kowloon district, the buildings are packed together tightly.

A person on the street wouldn't know that on the roofs above, thousands of people are living in ramshackle and sometimes dangerous conditions.

Hong Kong is really an affluent city. But Hong Kong does not have a very good housing policy. Natalie Yau, Society for Community Organization

Several blocks away, tucked in another old building is a non-profit organisation that helps the city's poor and underprivileged find a proper roof over their heads.

Natalie Yau has been working there for more than two years and says the government isn't doing enough to help people like Mr Chan.

"Hong Kong is really an affluent city. But Hong Kong does not have a very good housing policy. People live in poor housing just because of the failure of the housing policy.

"Now the government will provide public housing to low-income families but the amount is becoming smaller and that creates a long queue of public housing applicants on the waiting list."

Peak view

On a cold, misty day, I head up to Hong Kong's famous Peak district, where you can take in skyline views of the city.

Image copyright AFP Image caption Views over Hong Kong from the Peak which has the territory's most expensive property

It is pretty breathtaking, beautiful even, looking down. But behind the shiny steel facades and concrete blocks lies a much grimmer reality.

Poverty is a serious issue in the city, and that problem has been exacerbated by the lack of affordable housing.

It is not uncommon to see elderly men and women digging through overflowing rubbish bins, pushing carts loaded down with old cardboard boxes for recycling, or even sitting on the roadside, selling vegetables late at night. A large bulk of their income goes towards paying rent.

The lifestyle is very different on the Peak, where property prices are the highest of anywhere in the territory.

Interest rates are being kept extremely low currently and that means money has been cheap in Hong Kong so it's become very easy to get a mortgage Simon Smith, Savills

Typically houses go for between HK$240m and HK$970m (£20m and £80m) but even flats on this much-desired street address sell for multi-millions.

Simon Smith, head of research for Asia-Pacific at real estate firm Savills, says a number of factors have fuelled Hong Kong's asset price inflation.

"The Hong Kong dollar is pegged to the US dollar, so effectively interest rates are set in the US by the Federal Reserve. As we know, interest rates are being kept extremely low currently and that means money has been cheap in Hong Kong so it's become very easy to get a mortgage," he says.

"QE (quantitative easing) is another factor, not just out of the US but Japan and China and it always seems to wash up on Hong Kong's shores in some form.

"If we look at the fundamentals of the local market place as well, there has been a notable lack of new supply of residential units over recent years.

The previous administration failed to provide new land to the market, something the current administration is trying to address. But it's not a tap that you can turn on instantly."

Image copyright AFP Image caption Hong Kong is one of the world's most densely populated cities

Housing hopes

Back in Sham Shui Po, Mr Chan is shuffling up and down the hallway, waiting to use the toilet - the same room also serves as the communal shower.

He doesn't really understand monetary policy and how it works. All he knows is that he's been waiting a long time for a place to call his own.

"I've been waiting two years to get public housing," he tells me. "But all the government does is talk and say there is not enough land."

It is unlikely he will be able to get it anytime soon. The average waiting time for families to get their first choice of housing is four years.

But Mr Chan is also faced with another predicament. If he is unable to find stable work, he will have to downgrade to an even smaller space, which this time, won't come with a view.