PERTH'S rental crisis is so severe that workers and families are pitching a tent because they cannot find a home or apartment.

And they're being stung up to $280 a week just for a square of grass to set up camp.

Metropolitan caravan parks say they are at or near capacity and most campers sleeping in tents or caravans are not holiday-makers, but residents who cannot find a rental.

Rents in Perth have jumped 10 per cent in a year, with the median price now $420 a week and the official vacancy rate at just 1.6 per cent, according to the Real Estate Institute of WA.

It comes as estate agents report crowds of 50 or more would-be tenants turning up at home opens, and rental bidding wars becoming the norm.

Adding to the housing stress, WA's population growth is outstripping all other states, with 60,700 people moving to the state in the year to September 2011.

Even highly paid fly-in, fly-out workers are also being forced to live at camping grounds, some wanting to avoid paying rent when they're working away and others who simply cannot find a rental property.

Despite having a full-time job in the mining industry, Tom Shannon and his partner, Suezanne Leaker, have been knocked back for a roof over their head many times since moving from Melbourne.

They say they had no choice but to hire a tiny caravan and set up a temporary home with their four children at an eastern suburbs caravan park in February, paying almost $400 a week while desperately trying to find a permanent home.

"We went through homes nearly every day or second day looking for a house and there was always 30 people or more," Ms Leaker said.

"We have no problems paying for a house. It would just be great to have a back yard and room for the children not to be on top of each other."

Ms Leaker said housing in Perth had hit crisis point and caravan parks were now having to take formal applications to keep up with demand.

At another camping ground, qualified chef Brad Withyman and his wife said they had been living in a tent for five weeks while they searched for a home to rent. The camping ground was full of others struggling to find homes, Mr Withyman said.

"We just heard the same story over and over again with people saying, 'God, you know, this is what we're resorting to'," he said.

Another camper, FIFO trades assistant Edward, told The Sunday Times he spent his downtime in Perth paying $240 a week for a tent site to avoid the hassle of finding a room.

At Crystal Brook Caravan Park in Orange Grove, southeast of Perth, the manager said campers were "screaming" for proper accommodation. "We've had people call and say they've got nowhere to go but we can't help them," he said.

Mission Australia WA state director Melissa Perry said the charity was seeing families who had never experienced such chronic housing stress.

"It's just your ordinary Australians who are finding it really, really tough. We've had people asking for tents, sleeping bags, blankets, socks," Ms Perry said.

Salvation Army spokesman Warren Palmer echoed the need for more to be done to help people keep their accommodation and prevent them sliding into homelessness.

Despite the shortage, REIWA said it expected the rental crisis to ease this year as more people decided to buy their own home and investors bought property to cash in on high rental prices.

The rising number of people living in tents comes a year after the death of Brett Spies, 48, and his children Ben, 16, and Georgie, 13, who died when fire ripped through their tent at Timbertop caravan park in Mandurah. The family were living there after being evicted from their rental property.

A patch of grass at Perth Vineyards Holiday Park in the Swan Valley is costing campers $240 a week for a powered site or $192 per week for an unpowered site, and campers can only stay for a maximum of 90 days.

Central Caravan Park in Ascot $273 a week including power costs, for a space in which to erect a tent for a maximum of 60 days.