If you haven't clocked the housing crisis, you must be living on another planet. Matt Hartley's flatshare comedy, revived in its Hampstead Downstairs first home, is a report from the front-line: a look at the insane, yet everyday pressures of living in London.

Two couples squeeze into a one bedroom-flat, both seeking to save enough cash in one year to scrape onto the property ladder. Teenage sweethearts Ben and Rachel take the bedroom. Mel and Sam get the sofa-bed in the sitting room with no door. From the very first night – celebrated with champagne that cuts into their savings – it's clear that these four are going to fray and, sure enough, fray they do.

Hartley wrings his drama out of staple flatshare frustrations: petty squabbles over petty cash, daily chores that chafe. The two couples tiptoe around each other and, inevitably, tread on one another's toes. Hartley calibrates his irritants carefully – Sam's say-what-you-see nature rubs against Ben's masculine pride – and he charts the cold war of cohabitation very well: an arms race of passive aggression. With all four pushing 30 or past it, they're all too old to be living like this – but their generation is too stumped by the system to have any alternative.

Movement director John Ross makes the most of this in elastic montages that suggest time passing and space collapsing in on itself. As the cast press past one another or clatter through private coupley moments, Richard Hammarton's sly soundscore squishes several songs into one – as if even the airwaves are over-crowded. It all animates a play that often borders on banality, and director Lisa Spirling keeps things light and likeable throughout.

Deposit escalates as it grows political, and Hartley introduces a wealth gap that reveals political differences. Driven young doctor Sam, pulling himself up by his bootstraps, and Mel earn enough to save speedily, while teacher Rachel and comms manager Ben – both public servants – struggle even to scrimp and save. An inheritance windfall only exacerbates things and Natalie Dew is superb as the kind-heart backed into a corner, while Karl Davies cleverly softens Sam's shitbaggery with social unease.

Hartley recognises that the housing market – and, indeed, the rat race – turns us into competitors and drives at its most difficult dilemmas. Is it worth living in London if you can't afford to enjoy its opportunities, or are cheaper commuter towns simply unthinkable? It could extend its metaphors, playing up the politics of envy or the elements of austerity, but Polly Sullivan's design – a floor tiled with pennies – reminds us not only that small change can add up, but that our lives are made up of little things.

Nonetheless, while Hartley shows the symptoms of a crocked market, he stops shy of calling out causes. The housemates might just be able to see the Shard from their sitting room – a mark of the cranes pecking away at London's skyline – but there's no mention of foreign investors or political failures. Nor is home-ownership itself ever thrown into question, either as an individual or a social aspiration. With a topic this well-worn, Deposit needs to dig deep.

Deposit runs at the Hampstead Theatre until 10 June.