Ayazma, the shanty town where he lives, looks more like a Third World village than part of Turkey's richest city. Chickens roam freely. Loose planks serve as makeshift bridges across a muddy stream. The rocky dirt road ends halfway through the quarter. Many of the houses are accessible only by scrambling up the steep hillsides. When it rains, Ayazma is a sea of mud.
The inhabitants rely on electricity for heating during Istanbul's bitterly cold winters, and power cuts are frequent. Their houses are poorly insulated. They use waste plastic as fuel for the hut that serves as a bakery.
Ayazma is situated on the European side of Istanbul. The E80 motorway, which connects Turkey to Europe's road network, passes within walking distance. But Mr Kaya did not know he lived in Europe. "Do you mean they've sold Istanbul to Europe?" he joked.
Mr Kaya is doing better than most of Ayazma's inhabitants. His was the first house here to be connected to the water mains. Most locals collect their water from a tank, where the municipality delivers fresh supplies each week. Mr Kaya connected his own pipe to the main and started stealing water. When the municipality found out, it let Mr Kaya keep his pipe, but fitted a meter. He also has a satellite dish, which he shares with two other families. There are three satellite dishes in Ayazma.
The Kurds save hard for a satellite television: Kurdish language broadcasting is illegal in Turkey, but Med TV, a Kurdish station, broadcasts by satellite from London.
Gecekondu means "it arrived in the night". The shanty town houses are built illegally on government land, and construction is rushed so it can be finished before the authorities find out. When Mr Kaya built his first gecekondu house, the municipality demolished it. Undeterred, he built his current house in 10 days. The tiny, three-room bungalow houses Mr Kaya, his wife and four children. The roof is made of scrap metal; loose carpet tiles cover the dirt floor. Mr Kaya is building an extension.
Istanbul Municipality has ambitious plans to move all those living in gecekondus into new apartments, paid for by the state. But the mayor says the municipality cannot keep pace with the rate of immigration to the city. He wants the government to introduce a permit system, forcing those who want to move to Istanbul to apply for permission, and prove they have a job and somewhere to stay in the city.
"Nobody chooses to come here," says Mr Kaya. "All the Kurds came under force." He used to own a roadside shop near Turkey's border with Iraq. He came to Istanbul after his village was forcibly evacuated by Turkish security forces.
Villages in the south-east are being cleared in an effort to stamp out the Kurdistan Workers' Party (PKK), which wants autonomy for the Kurds. This has sent a wave of refugees to the large, safe cities of western Turkey, adding to the number already flocking here in search of work.
Many in Ayazma live in worse conditions than Mr Kaya. In a neighbouring house, 12 people share three small rooms: most are out at work. Mr Kaya's friend, Mehmet Yildiz, lives in a single-room house with his wife and baby. There is hardly any furniture.
They have no bathroom, their toilet is an open air pit. Mr Yildiz is 20: he makes pounds 110 a month working in a textile factory. His baby has diarrhoea; he says he cannot afford to take her to a doctor. "Ayazma is far from God," says Mr Kaya.
Some of Istanbul's immigrants lead a more comfortable life. Yusuf Kose came here five years ago from Rize, on the Black Sea coast. He works in an ice-cream parlour in the Bosphorous suburb of Bebek, the city's most prestigious residential quarter.
Bebek is a few miles up the E80 from Ayazma, but at the other end of Istanbul's wealth spectrum. This is where Istanbul's rich live, on the shores of Europe.
Their yachts are moored in the Bosphorous, the straits which divide the continents of Europe and Asia. Expensive seafood restaurants line the shore; luxury villas look down from the surrounding hills. Prices for these villas can be as high as $6m (pounds 4.5m), according to a local estate agent. But for the dome and minaret of the local mosque, this could be the south of France.
Mr Kose lives half an hour away in Sariyer, a cheaper neighbourhood overlooking the Bosphorous. But he prefers his workplace. "Istanbul is a European city, but Bebek's a little more European," he says. "Here, the culture is European, the people eat in restaurants every night."
In Ayazma, Mr Kaya disagrees. "Maybe Turkey can be Europe for the rich. For the rest of us, it's impossible."Reuse content