About once every six weeks I go to my least happy place. It’s a massive warehouse in the industrial back blocks of Port Kembla, near Wollongong in New South Wales, housing a storage facility called Super Easy Storage. Because it is a no-frills operation, it does not offer 24-hour access like the more upmarket companies do, so I have to call ahead to say I am coming, giving a minimum of three days’ notice so they can arrange to make our plywood crates available, shifting them to ground level from towering stacks that stretch in an endless cubist landscape of anonymous geometry.

The crates (which Super Easy calls modules or pods to make them sound groovier) contain the possessions my mother has brought with her as part of her decision to relocate to Australia from the UK after 60 years and live with us. A brutal cull reduced her possessions by two thirds, but she still brought 2,000 cookbooks, as well as a vast trilingual general library, a cumbersome early-model knitting machine she has not used in a decade but cannot bear to part with, extravagant quantities of china, canteens of cutlery, a battery of professional cookware sufficient to equip a small restaurant, enough fabric to open a shop, a collection of vintage luxury-brand handbags, the wardrobe of Marie Antoinette and all her furniture. Many pieces are fragile, obsolete, or of little value, except of the sentimental kind.

Until we build an extension to our small house, there is nowhere to put it all. And so it remains in storage, locked away in a desolate place. Every so often we go and retrieve something she pines for. It is like sifting through an archaeological dig.

Bec Taylor, the Super Easy office manager, who helpfully supplies box cutters and tape when I have forgotten to bring my own for opening and resealing, comments that we are atypical clients, visiting as frequently as we do. Most stored possessions are like residents in nursing homes: placed out of sight, somewhere safe and secure, then forgotten from year to year.

Ours has become a lock-and-leave culture: mobility, downsizing or long-term building and renovations, deceased estates, divorce are all factors in the relentlessly increasing demand for off-site storage. What often begins as an interim solution of two or three months soon extends into a more permanent arrangement stretching into years.

Kennards (one of the top-three self-storage companies, together with National Storage and Storage King, who between them operate around 40% of the sector) have more than 800 facilities in cities across Australia and New Zealand and are expanding all the time into regions where the population is growing, including the Gold Coast and Badgerys Creek in western Sydney. Typically, domestic customers prefer to use self-storage that is five to eight kilometres from where they live.

The chief executive of Kennards, Sam Kennard, says 75% of his business is domestic and the median stay is about 30 months. The average unit rented is eight square metres. What started in 1973 as a “pretty basic business on industrial sites in tin sheds, with no insulation has become a more retail-friendly experience with improvements in temperature control, light, safety and access to make it more pleasant for the customer,” says Kennard.

According to a recent Ibis World report, the self-storage business is booming; it notes that the increased growth in e-commerce means that there is more demand from online retailers to rent storage space to manage inventory on short leases in convenient locations.

At the budget end of the market, Super Easy’s Bec Taylor says: “Some of our regular clients are students from elsewhere who put their stuff in storage over the summer to save themselves a few bucks on rent while they go home for the holidays.”

Professionals moving overseas for work and renting out their homes are another obvious group that may put furniture into indefinite storage as their contracts get extended beyond the original period.

The increase in relationship breakups is a bonanza for storage companies. When couples split up and move separately to somewhere smaller, there is no room for the things they accumulated together. After my first marriage ended, I went overseas indefinitely and rented the smallest unit available near the airport. I had my boxes moved there a few days before my departure and remember the deep satisfaction in having calculated the space precisely down to the last centimetre, so that on my day of departure, I could drive my car in to fit snugly as the final piece of the possessions puzzle: there was a sense of freedom that came from slamming down that roller door on a chapter that was closed.

Not all storage is legit. Back in the early days, there were no CCTV cameras at facilities. These days they are ubiquitous, as the convicted former NSW detective Roger Rogerson would discover to his cost when he was filmed, together with Glen McNamara, removing the body of Jamie Gao, a suspected drug dealer, from a Rent-A-Space unit in Padstow after shooting him dead there in 2014.

In the US, self-storage units are frequently associated with criminal activity, including growing marijuana in climate-controlled units (usually used for art or wine; the electricity bill is the giveaway). Timothy McVeigh, the man responsible for the Oklahoma City bombing, kept explosives in storage units in Kansas, renting them with fake ID. The terrorists who attempted the first World Trade Centre bombing also used storage units for their explosives materials. In a particularly bizarre and gruesome case, 12 bodies were found in a storage unit in Suffolk County in the US after Joseph O’Donnell posed as a funeral director who hid the deceased instead of cremating them, giving clients ashes that were not the remains of their loved ones.

In Australia, “climate control is not a big feature for personal items”, Kennard says.

“We do offer wine storage in 20 of our centres. I have heard about the marijuana growing in the US, but most of our spaces are dark and have no power. The liberalisation of pot law there means that storage companies may be offering space in units with power for this newly legalised industry as a good way to build occupancy.”

Like every other business sector, self-storage has been disrupted by technology. Valet storage is a new option. Launched in 2017, Clutter is an LA-based business that packs, picks up and stores your possessions securely. It also photographs, barcodes and catalogues them for easy retrieval and delivery (“as easy as ordering pizza”, its website promises).

Sydney-based platform Spacer is another sharing-economy solution (slogan: “the place for space”). The brainchild of founders Mike Rosenbaum and Roland Tam, it has been connecting people who need stuff stored with people who have available storage space for rent since 2015. Prices are often about 30% lower than those offered by the major players. Clients are automatically insured up to $10,000 .

Kennard is watching these newcomers with interest but sees them as “a very micro, boutique solution, unlikely to penetrate the market in a significant way”. Maybe, but there is no doubt that the combination of digital technology and robotic innovation means that it is possible for the tedious business of finding somewhere to park things you have no immediate need or desire for to be delegated to a non-human.

The social researcher Hugh Mackay sees attitudes towards storage as “an unexpected social indicator that tells us a lot about our attitudes and values”.

“We are more materialistic than ever. Consumerism is rife, supported by mass marketing that says ‘my possessions are the measure of my worth’. People cling to their stuff as a kind of reassurance and a symbol of permanence, a rock in a sea of transience.”

But that could be changing. Perhaps the current boom in storage is generational. According to sharing-economy guru Rachel Botsman, millennials are less interested in possessions (a concept known as nownership) than in experiences. In that case the storage boom may be finite even if, for now, the trend towards decluttering seems to be having little impact on their parents.