Two years ago I moved from New York back to southeast Michigan. Iggy Pop once complained that it's no fun around here, but groups like The Stooges, Negative Approach and Underground Resistance proved that there is a chthonic force coursing beneath these flatlands. Last summer a Clay Rendering performance channeled that raw power into thunderous, richly textured drone, momentarily making a Hyperborean cavern out of an overheated DIY venue. Here, I thought, is a new heir to the tradition.

Clay Rendering are the duo of Mike and Tara Connelly, a married couple based in Dearborn, just outside Detroit, who previously made oblique ambient music as The Haunting. Mike used to play noise music in Hair Police and, until recently, in Wolf Eyes. In this new group, he plays guitar and sings. Tara plays accordion and piano. They're associated with Dominick Fernow's Hospital Productions label, which put out their first EP, Vengeance Candle, and recently released a second record called Waters Above The Firmament. They're currently supporting the record with an SST-style label tour of the American south and east, accompanied by fellow Hospital bands Lussuria and Dual Action.

You could call Clay Rendering industrial, or darkwave, or drone, but these genres are just starting points for their explorations of layering and duality. 'The Pest', the third track of Waters Above The Firmament, is built around what sounds like an alarm clock – an insistent, unsettling beep. But this sound is inseparable from a hypnotic, serpentine guitar riff. Together, these lines form an invitation to wake up without shaking the dream. Clay Rendering work on the boundaries between clarity and obscurity, conscious construction and unconscious exploration. And just as the alarm superimposes its metered time on the organic pulsation of the riff, so this music seems to exist in multiple temporalities. 'Temple Walking' depends on programmed beats and a highly processed guitar sound, yet draws its momentum from somewhere primeval. In the music video, Tara and Mike appear as leather-clad votaries of some new Delphic cult, casting herbs onto a brazier and singing through the rising flames.

But visiting the duo at their home, I'm struck by the conspicuous absence of grim vibes. They live in a small, well-worn white house with a patch of green lawn out front, built back when Dearborn was a production center for the Detroit auto industry. As soon as we pull up, Mike and Tara are at the door, welcoming us warmly and introducing us to their friendly long-haired dachshund, Steve Perry. The living room stereo is blasting Ke$ha's 'Warrior'. We step past the anonymous suburban exterior into a lovely home decorated with a collection of thrift store finds, repurposed kitsch, and a huge Manowar poster. Mike and Tara take pride in this place, especially their backyard, and they spend a lot of time just hanging out here, jamming and reading and listening to Top 40 pop. They laugh easily and thrive on each other's company. These people are clearly skilled in the art of being happy.

Of course, this shouldn't come as much of a surprise. Clay Rendering prove how silly it is to feel the need to "humanise" the people who make extreme music, as if they ever needed it. After years of gee-whiz interviews with black metallers who turn out to be friendly dudes, we know that stern aesthetics cannot just be explained away in terms of misanthropy or psychosis. But it would be equally misleading to draw some clear-cut dichotomy between music and life. The most interesting thing about the contrast between the Connellys themselves and the Connellys as Clay Rendering is that, despite the difference in mood, their creative process is inseparable from the rhythms of their life together. Their studio is the upper floor of their house. This allows them to write spontaneously, acting on sudden inspirations that might otherwise be lost.

"Usually it's inconvenient times when you end up writing something," Tara explains. Indeed, when they sit down with the express intention of writing a song, it usually feels like pulling teeth. They develop ideas through a collaborative process of play and experimentation. If it ever starts to feel like "work," says Mike, they take a break.

He and Tara put together the skeleton for 'Myrrh Is Rising', the final track on Waters Above The Firmament, on a single afternoon last December. They vividly recall sitting on the couch while burning myrrh incense, watching the snow fall and the smoke rise. Tara started playing around on keyboard, and the melody came to her. Mike joined in, scribbling out some lyrical ideas. It was almost automatic, a shared unconscious coming to the surface, and it happened, as much of their writing does, as a kind of conversation. You can hear traces of this dialog on "Myrrh Is Rising," when Mike's heavily processed whispers creep into the still spaces between Tara's piano lines.

With such an intuitive approach, they're reluctant to frame their music in terms of direct influences. Just as their songwriting depends on lazy afternoons and stolen moments, the project itself took shape in a kind of blank space – August 2012, when they weren't listening to a lot of other music. They were more attuned to the season itself, to the intense heat, and to the intimations of autumn. And, recalls Mike, "we were listening to a lot of comedians." Not only did stand-up help clear the way for Clay Rendering, it informed the structures of their songs. "There's that quiet space in between jokes that you're afraid of," says Tara, "and I think that's true when you start playing music. You're afraid to leave the quiet space in between."

The quiet space of that summer may also have allowed old influences, long become instinctive, to assert themselves. When I float the notion that Clay Rendering sound like a cross between Celtic Frost and Lycia, the duo laugh – these are two of their favorite bands. They also see a relationship between their work and relatively "poppy" ambient albums like Brian Eno's Music For Airports and Aphex Twin's Selected Ambient Works Vol. II, which comes to the foreground on the opening and closing tracks of the new record.

But under the distortion and reverb there is a layer of acoustic folk music. It's audible in the archaic melodies of 'Temple Walking', and in the hand-drums of 'The Pest'. Tara's grandfather was a bluegrass musician, and after learning the oboe and piano she tried her hand at banjo. Eastern European folk inspired her to take up the accordion. She loves Bulgarian women's choral music, especially the Trio Bulgarka, and other traditions from the Russian steppes and the Ural mountains. Mike grew up listening to Celtic music. He's especially fond of Lark In The Morning, an early collection of traditional Irish music recorded in the living rooms of the musicians. What all of these folk styles have in common is the drone - the same drone that runs throughout Clay Rendering's music.

Where many bands in their scene draw inspiration from occultism and theology, Clay Rendering are more interested in literature – the duo's shared experience reading Russian writers like Dostoevsky and Nabokov was a formative influence on the project. Their living room bookshelf provides as a good a key to their sensibility as any talk about their record collection. Murakami sits alongside Tolkien, Clive Barker alongside Steve Martin. I'm pleasantly surprised to find several books by Michigan-born horror author John Bellairs, whose The Revenge of The Wizard's Ghost once set my hair on end. Bellairs' books were an important part of Mike's childhood, and there are connections in atmosphere within Clay Rendering to their improbable combination of darkness, elegance, and whimsy.

As the duo refined the four tracks of Waters Above The Firmament, they explain, they coalesced into an abstract narrative. This can be understood as a seasonal cycle, with each song mapping onto the time of its composition. "The middle songs were the ones written in the summer," says Mike, "and the other two written in winter, with 'end of winter' and 'beginning of winter' vibes." The album takes us from the bleak month before spring to the walled stormclouds of early summer, from the stifling heat of August to the serenity of the first snow. It is difficult to listen to a single track without letting the next one play, and even harder to play on shuffle.

Currently, the Connellys are most excited about Roberto Bolaño, whom they see as a kindred spirit in some ways. Mike praises the "mix of clarity and dissonance, realism and surrealism" in books like 2666 and The Savage Detectives. He tries to pin a word on the style, and Tara jumps in – "intensive realism." "It's that feeling of being in a situation without it being positive or negative," she elaborates. "Good things might be happening and bad things might be happening, but you're just in it. It's a hypersensitivity to details, to the quirks of other people, to the sounds around you…"

Clay Rendering share this intense attention to the specific qualities of particular times and places. They aspire to a realism that takes us beyond mundane perception, but rather than tearing the veil from the world they use a process of layering to show it to us anew. "I've always enjoyed mucking things up," says Mike, "and now I enjoy cleaning it off a little more. Playing with the idea of obscurity and clarity, dissonance and harmony." His vocals, while still drenched in effects, are now far more intelligible than his inchoate screaming in Wolf Eyes and Hair Police. They hover on the edge of meaning, tempting us to interpret them. His words are central to the conception of each song, not just afterthoughts superimposed on prewritten tracks. This aspect of the band is only growing more central, so Mike hopes to include lyrics booklets with future Clay Rendering releases.

Upstairs in the duo's studio, a small attic with a carpeted floor that serves as surprisingly effective soundproofing, a small window lets in afternoon light for the gladiolas that Tara is growing on the sill. We drink some excellent homemade pour-over as we listen to the new record. It opens with the gently swelling chords of the title track. "The accordion is really what drives this song, weaving in and out," says Mike. The duo built it up by jamming on it for hours, with Mike slowly adding guitar parts. Just shy of the two-minute mark an electronic hiss enters the mix, cutting through the blissed-out reverb and setting up a plunge into more dissonant chords. But even as the elements multiply and the mood darkens, the track never attains the "complete, blown out extreme" of Mike's earlier music – it's designed to let us "dive in," he says. Tara recalls that she was shocked to find herself turning the reverb down.

The slow-motion power of 'Temple Walking' comes from pairing an ostinato synthesiser riff with a massive beat. Robert Beatty, Mike's old bandmate from Hair Police, contributed the synth part, and the duo liked it enough to develop the song around it. But Mike and Tara have surprisingly little to say about their beatmaking techniques. They're pretty sure that the drums on every track are different. They use old drum machines and production software, but also hand drums – "whatever works." This lack of a consistent drum sound isn't eclecticism or indifference, but a full embrace of the possibilities of modern production, and a refusal to set any lasting limits on their creative play.

One of the most powerful moments in 'Temple Walking' is the mournful, falling melody that enters about a minute in, answering the verse riff. As Mike drones away on the root note, Tara carries the melody, her accordion transformed by reverb into some kind of apocalyptic French horn. The accordion is at the heart of Clay Rendering's sound, an "earth element" whose more organic tones balance the electric "fire" of Mike's guitar. There's something impersonal about it – unlike other wind instruments, which depend on human breath, the accordion simply draws in the wind and gives it a voice. Tara explains that she likes the "fullness" of her instrument, its many harmonic possibilities.

Record finished, we step out back, and stand around the fire-pit on their small patio as they make a fire. The wood is a little wet from the last night's rain, but it eventually catches, wafting thick smoke into the blue sky. Steve Perry frolics beneath the branches of an old oak tree that casts a deep shade in the summer. Tara shows me the garden plots where she grows some of the aromatic herbs they like to burn. She sees the yard as an "introspective space." It's a clearing or opening, fertile ground for new ideas. This is where they experience the natural cycles that infuse their music so strongly. In Michigan, Mike explains, "the weather really affects everything, in every season, whether it's this brutal winter we just had, or the hot summers, or the relief of spring and fall. So it can't but affect the way you write. Whether you're reacting to the weather or embracing it, it's a great feeling."

"As weird as it sounds," says Tara, "we spend a lot of time just hanging out here." "You almost feel like you've escaped," Mike enthuses, "because it's just two people, and you don't have a phone, and you don't have a computer to go to, so you're just outside with each other." In one sense, nothing could be less weird than this backyard lifestyle. It's a time-honored part of American homeownership. But for the Connellys the weird is coextensive with the normal, or disguised as it, hiding in plain sight. Mike and Tara take the mundane isolation of the suburbs and push it so far that it becomes something else entirely – a hermetic seclusion in which the barriers between life and art dissolve. The sheltered green space of the backyard is the centre of a world that they create for themselves. The mystery of Clay Rendering is that its eerie beauty, its wall-shaking power, and its feeling of enchantment come less from far-flung fantasies than from the duo's life at home. This is their "intensive realism", anchored in a shared reality that is itself an aesthetic project – and all the more real for it.

Clay Rendering's Waters Above The Firmamentis out now via Hospital Productions