A few years ago, Clare shared a flat with two Frenchmen who shared a room. One worked nights, the other during the day – but inevitably there was overlap. The shift worker sometimes returned home, often with his girlfriend in tow, before his roommate was awake and out of bed.

Their solution was to have sex in the kitchen. “I’d have to wait until they were done to get my packed lunch out of the fridge,” says Clare. “I only stayed about three months.”

Most people have a flatmate horror story, and most are about sex: loud sex, risky sex, disruptive sex, sex in communal spaces. As “generation rent” gets older, more of us are sharing our homes, and by extension our personal lives – with varying degrees of consideration.

Joy remembers being trapped in her bedroom as her flatmate and his girlfriend indulged in some afternoon delight in the living room; she later learned that he had also been competing with their other flatmate to see who could be louder.

Meg’s first flatmate had sex in the shared bathroom with a partner who – Meg was left in no doubt – was on her period. “It was like he was proud,” she says.

Nicola’s story, however, perhaps sets the bar for flatmates breaking boundaries. Getting ready for work early one morning, she was caught up in a flatmate’s midweek, drug-fuelled orgy. When one of the parties involved was booted out by the others into the hallway, Nicola, still in her PJs, was forced to play peacemaker. “I explained that it wasn’t fair to throw her out and could she please let this girl rejoin them.” Impressively, “it was all sorted out by 7.20am,” says Nicola – “and I actually also got on very well with the flatmate.”

With time, such stories inevitably emerge as amusing anecdotes about a period of life that you don’t regret but – now that you live alone – you are glad to put behind you.

But living with others – once a rite of passage for those starting out – can now extend well into your 30s and beyond. People are cohabiting, often with acquaintances or strangers, far into their adult lives, thanks to a number of factors that are coming to define our times: unaffordable housing, insecure employment and the deferral of milestones such as marriage and children.

The most recent English Housing Survey found that people now on average do not buy their first home until they are 33; a report by the Resolution Foundation predicts that half of millennials will still be renting privately in their 40s. Coupled with more dating and casual relationships later in life, this means more people are also navigating their sex lives in shared houses.

“The housing crisis really does affect every facet of your life – that includes your romantic relationships,” says Caitlin Wilkinson of the tenancy advocacy group Generation Rent. She notes that couples may also feel incentivised to move in together sooner than is advisable to save on rent – then find themselves unable to break up because of inflexible tenancy agreements.

“Structural housing issues do have a real effect on private relationships,” says Wilkinson. “They have basically eroded our privacy.” And that may mean we not only have less sex – but worse sex, too.

Kate Moyle, a psychosexual and relationship therapist, points to the reported “sex recession”, and statistics that show that younger generations are having less sex than in the past.

If both people in a two-bedroom flat have partners, that is four people in a small flat, often with thin walls. But personal space – not to mention freedom from distractions or monitoring – can be critical to sexual pleasure, she says.

“Being able to hear someone in the kitchen and knowing people are in the house means that you don’t feel able to fully let go – especially if you’re someone who struggles to get in the right headspace for sex anyway; these kind of things are probably going to be extra inhibitive.”

Miriam Tierney, of the flatshare listing site SpareRoom, says setting house rules can help to minimise conflict. These might include: letting other flatmates know when a partner is staying over, or discussing how many nights a week is appropriate; staying at your partner’s house as much as they stay at yours; and, if you’re the guest, buying milk every once in a while.

“If you know your walls are thin, you can bring it up early on as a lighthearted joke,” Tierney suggests. “It is an awkward one, and if you were to bring it up with your housemate, they’d probably feel as awkward as you.”

Moyle says if you want to show consideration to your flatmates, “it’s about communication, and mutual respect. Whether you’re living with people you really know or not, you are still in a relationship with them.”

When expectations are aligned and it’s safe to talk about anything, most problems can be solved

It is also important to be realistic: in close quarters, some awareness of your flatmate’s sex life is inevitable, he says. “If it’s a one-off, I can forgive that person and think: ‘Good for them, they had a good time.’ What you hope is, if it happens repeatedly and you are really uncomfortable about it, you feel you can say something.”

People forced into proximity with each other need to be prepared to cut each other some slack. “Try to be open-minded and accept that everybody’s sex lives are different.”

Harlan Cohen, an advice columnist and author of the book The Naked Roommate, says flatmates don’t necessarily need to be friends – but that those “who want to get along, will want to get along”. He suggests establishing a house rule to voice any grievances within 24 or 48 hours of the incident, or let it go. “There’s less drama and more dialogue,” says Cohen. “When expectations are aligned and it’s safe to talk about anything, most problems can be solved.”

It boils down to a fundamental point: it is best to live with someone you feel comfortable (or at least less awkward) having these conversations with. Although sharing can be a great option for many, says Wilkinson – and preferable to living alone for some people – the issue is the lack of options. “We need to see more affordable housing of different types so that if you feel you are at the stage of your life where you want more privacy, that isn’t unobtainable. I’m not even talking about owning a house – just renting a space that is your own.”

In the meantime, dating while cohabiting means managing your relationship with your flatmate as well as your partners.

Michelle has been sharing a rental with Megan for nearly seven years and says, over time, they have learned to respect each other’s needs. On Megan’s regular date night, Michelle sees films, friends and recently took a jewellery-making class. “It’s in both our interests to work things out.”

Megan, for her part, tries “to be really respectful of the shared space – I’m not shagging in the living room. The house is our space, together. That’s kind of the bottom line.”

Michelle has another tip. “Noise-cancelling headphones.”