One of the oddest of the Britart/Sensation crop, Richard Billingham is a slim, fit-looking 29-year-old, with straight eyes when they eventually settle on you. Fresh into the gallery and surrounded by crates of his work, he was at first reserved, even shy, like he just wanted to be left alone. But when we got talking over a couple of pints and sandwiches, he emerged as a friendly, level-headed bloke, from underclass Birmingham originally, and with his very own take on the world.

Billingham's Douglas Hyde show is virtually a retrospective stretching back a decade to his earliest photographs of his family, up on the 11th floor of a Birmingham tower block. It's a kind of voyeur's soap opera. Richard's old man, Ray, is a tragic but beguiling character who drinks himself legless. Richard's Mum, Liz, smokes fags, watches telly, does jigsaws and general maintenance. The younger brother Jason drops in betimes.

There's a strange cannibalistic warmth to the pictures, as Billingham's folks unselfconsciously slob out on the sofa; keel over in front of the stereo (as Ray athletically does in one snap), or have screaming matches, with Liz bunching her fists and giving Ray loads, while Ray, framed by Little Miss Moffat and shepherd figurines behind him, looks mournfully in the other direction.

The dog's another character: caught flash-pupilled with the cat beside the fridge with the brown dribbles all down it; or thoroughly chewing its behind on the sofa. According to Billingham, these were originally taken as a basis for paintings, which you can clearly see in one posed triptych of Ray with Martini bottle, very much a a la Francis Bacon. Billingham started taking colour snaps about the time his Mum moved back in, and there are many affectionate pics of her smothering cats in her big tattooed arms.

Billingham is affectionately proud of his folks in a barmy way. An awful lot of people once wrote them off. The world ain't knocking Ray and Liz now, however. Their photographs are in collections like those of Saatchi, Rockefeller or the New York Metropolitan Museum, while Richard has had one-man shows in LA, Paris, Milan, Frankfurt, Brussels and Rome.

The fame came overnight in 1996, when at the insistence of a university contact - Michael Collins, picture editor of the Sunday Telegraph magazine - he published them in a book, Ray's A Laugh: "I was just amazed at all the attention. My dad said, `has no one seen a dog licking the floor before?' I thought everybody knew how everybody else lived. I mean it's easier for rich people to know how poor people live, because how can poor people know how rich people live, because you have to go up the ladder, don't you, rather than going down?"

Ray's local, but Liz is Polish originally. "Her parents came over here I think after the war. Dad's 20 years older than her. He'd already had a family and he got divorced and then he met my mum when she was 20.

"Dad was a machinist - he earned quite good money in the 1970s - £5 an hour, that was a lot of money then, but then Thatcher got in and closed down lots of little industries, and he got made redundant in 1980. He was always a heavy drinker, but that's when he started drinking in good earnest. He said to his workmates, `when I finish up, I just want to lay back and be done'. That's Shane McGowan territory. Shane McGowan is my favourite songwriter."

Originally, the family lived in a terraced house, but they blew all the redundancy money and, in desperation, sold the house for £2,000, while Richard maintains it was worth about £30,000. Then they moved to the council tower block, where Ray just sits in and drinks. "That's the thing about my dad, there's no subject he's interested in, except drink."

Wherever he got it, Richard always had the artistic bug, a determination which sustained him better than his five brothers who, he says, are all on the dole. (He and Jason are Ray and Liz's; three others are step-brothers from Ray's first marriage, while another one is a child Liz had before she met Ray).

As soon as he could, he got out, and did a degree in painting at Sunderland University, after 16 other colleges rejected him. "I wasn't happy there, 'cos the area was the heaviest little shit hole. The worst thing about it was that little kids would just throw bricks at you on the street for nothing. It made me realise how good the Midlands were."

After college he returned to Birmingham, and worked stacking shelves in Qwik Save, doing art by night. After the overnight fame, he stopped taking still pictures, but moved on to Hi-8 video footage, resulting in the 47-minute TV film called Fishtank, commissioned by Artangel, aired as part of BBC2's TX series and now committed to 35mm film.

The latest stills in the Hyde show are depopulated landscapes: dead-end waste ground; patches of semi-rural/industrial dereliction behind red-brick walls; threadbare greens and eroded playgrounds between housing estates; a windblown spinney mirroring a painter's cloud-puffed sky.

"I wanted to keep the intimacy, but do away with the subject matter, so I thought what's the most boring subject I can take pictures of? So these are places I passed on the way to school as a kid, or on the way to my Mam's."

He still uses unheroic equipment - "just your regular SLR 35mm, an Olympus 0810. They look a bit like snapshots, because I don't measure them up or anything. I just lift the camera quick and take them. And I never crop, because then you're interfering with your original intention."

The Hyde show also features a couple of videos of his brother Jason, one of him smoking "backwards", another of his fingers berserk on a Playstation. "I think his record is about 40 hours. When he's coming down off speed, he needs summat to do, he gets blisters on his fingertips. It's quite common on estates, people haven't got jobs, they've nothing to do. It's like my dad drinking in't it? It's sad really.

"Jason was taken into care when he was coming on 10. A social worker came round and saw that he was being neglected, and he got taken into this foster home. He seemed to like it. He had clean clothes and went to school on time, but he didn't have any freedom, whereas when he was with my parents he could go off for three days, and they wouldn't bat an eyelid."

Meanwhile Billingham himself is now a creature of two very different worlds, and somehow, of neither. "When I came back to the Midlands, I spent a couple of months going into local pubs, talking to people and trying to be like a local person, but I wasn't the same, I wasn't innocent anymore.

"There's nobody where I live I can really talk to. I'm not lonely but I'm alienated. In London I've got friends, like Esther who you met, she's a curator. I like Tracey Emin but I don't see her very often. I like Gary Hume. It's funny when you show in group shows with people, they don't really talk about their work, they just drink together. They're secretly in competition, so there's a tension there."

He bought a house in the area 18 months ago, but has no studio to work on his "imaginary" paintings, but he's working from sketches, and some photographs. He split up with his girlfriend, a social worker, a while ago. He wasn't ready for a family then, but he says: "I do want to have kids eventually, but not yet. I even have names for them, Francis and Rebecca . . .

Richard Billingham's exhibition opens tomorrow at the Douglas Hyde Gallery