'Welcome to our home: pristine one week, filthy the next.'

If a house could have a split personality, ours would be all over the place.

For two weeks, all is ordered. It feels calm, like an infomercial for something you spray that smells like a forest full of fresh blooms and issues little sparkles from its nozzle. Surfaces are clean and clear. The dishwasher is stacked and unpacked. We might even get fresh flowers. I feel like I should wear white a lot.

The other two weeks  – this two weeks – we descend into chaos. There’s an uneaten sandwich, thankfully still in its ziplocked plastic bag, on the middle bedroom floor. It could lie there for days, slowly turning green, then furry. Oh, I’m lying. It could lie there for a full two weeks if I don’t pick it up.

There will be, most mornings, a single, precariously balanced sheet on the toilet paper roll – if there’s any at all. The front room will closely resemble a rat’s nest, or something Catweazel might emerge from after a period of hibernation.

Cups will sit half-full, topped with a shrunken little moon of congealed milk, on the edge of desks, where they might topple at any moment.

Our washing machine will operate with only the tiniest of loads - perhaps a pair of black skinny jeans, one pair of ridiculously little knickers and a sock. I say 'a sock' because that's how we do socks in our house - in the singular. Somewhere (in a knot in the back of a cupboard, in a school folder half-tucked in a backpack) will be its pair. The cupboard could be at their mum's place. The folder could be too. We'll never really know. But there's a good chance that single sock will never see its twin again.

I'm trying to adjust to this change in circumstances, but I'm very new to this parenting thing. I mean, am I even a parent? Not really; I share a house with my partner's two teenage kids, aged 13 and 16, half the time, and they are with their mum for the remainder. I'm not a friend, not a mother, a bit more than their dad's girlfriend. Beyond that, I'm not quite sure.

When we first moved into the house, feeling our way ever-so-tentatively around each other, I was just glad they'd speak to me. It seemed churlish to bleat about PICKING UP THAT BLOODY MANDARIN PEEL NEAR THE HEATER.

When we got past that, I waltzed into my 'free and easy' phase. What did a bit of bench wiping matter? Might as well pick up the sports shoes in the hall - I'm going that way anyway. Messy rooms? That's why they have doors. I'll just shift my thinking, I thought - perception is reality. Two weeks of order, two weeks of chaos, but no grumbling. Perfect.

Until it wasn't.

And now I find myself getting very bloody cross when I walk into the kitchen and find lids off things that should be lidded and fridge things not in the fridge and melting ice cream and a small stem of parsley lying limply on the floor. I issue regular reminders to 'put things away' and 'don't forget to', but my timeframe for action is very different from theirs. Theirs could be any time in the next day or so. By which time I'm gagging and the slimy dregs of a cracked egg have become an immovable inclusion in the Caesarstone.

It's a small comfort to know I'm not alone. Friends with teens have universally embraced the 'closed door' policy: if they can't see the mess, they can pretend it doesn't exist.

Kimberley O’Brien, principal child psychologist at the Quirky Kid Clinic in Sydney, tells me there's actually a reason for all this mayhem. It makes me feel a bit better, but not much.

"They are trying to establish a space," she says. "You'll get boys who spit around themselves to create personal space, a barrier; kids who leave tissues and personal body fluids around their room so you can smell it. It makes it a bit of a no-go zone so they get some personal space."

I suppose I should thank some greater deity we don't have a spitter. But he has started hoiking a bit. I've told him girls won't like him if he keeps it up. That has at least moved the habit to the bathroom, the more logical place to engage in more, well, viscous habits like this. Still, I fear my ability to embarrass him out of them might be limited.
Kimberley says parents - and not-quite parents like me - should accept that kids are never going to change.Great.

"Getting kids to take responsibility can be a lifelong parenting battle," she says. And she says it's ridiculous to point to the good old days when we were young and our rooms were pristine (they weren't) and we did what mum and dad said (we didn't) and we were seen and not heard (we weren't). For teens, clean rooms and ordered homes have never been a top priority - why would they be when there are friends and boyfriends and pimples and clothes and ... well, you get the picture.

So here's the plan. I will:

1. Build our relationship.

"That's the only way you can motivate change," Kimberley says. It might not seem like it, but the teens we live with actually want to get on with us. They like having a relationship with significant oldies. And they want it to be a good one.

2. Pitch in so we help each other.

(Kimberley, I will try, I promise. But can I use gloves?)

3. Throw in a motivator.

"Generally, it's best to look for an experience," Kimberley says. It could be having a friend over or doing something they like to do. If you have a teen who isn't that motivated, give shorter timeframes for action and give smaller rewards more frequently - even thanking them can be a start.

4. Give lots of praise for helping out.

(I can feel a bit of internal resistance here, but I'll give it a shot).

5. Recognise the positive things they've done.

And resist the inclinations to talk about them in a negative way. One whiff I've been gabbing to your friends about their messy room, and apparently I'm done for.

I'll let you know how I go.

And if all else fails, I still have an option. I can always close those bedroom doors.

Like this? Why not try ...

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