The fire crisis has reached a breaking point, with the last remaining high ladder truck in the Lower North Island breaking down.

The breakdown means fire crews only have access to one ladder truck that only reaches four storeys high, or five at a stretch, Thorndon senior station officer Mike Thomason said.

Thomason and his crew attended a job at Malvina Major retirement village in Khandallah about 6.30 last night, taking their last 100ft ladder truck to the job.

"On its way back from that fire call, the transmission ceased to function and we literally just had to pull over on the side of the road," he said.

The firefighters tried to fix the engine and even called out mechanical help, but the appliance couldn't be restarted and had to be towed.

The appliance, a Thorndon ladder, is the only device capable of reaching more than 18 metres, and now the closest device needed for anything more than that for the Lower North Island is in Hamilton.

Wellington is supposed to have two trucks reaching 100ft - which Thomason said is about eight to 10 floors of a building - but one had already been out of action with mechanical issues. Now both are unavailable.

"We're currently borrowing one from the Hutt Valley. It's 17 metres, which at best gets us about four or five floors up the side of a building, which is insufficient for the high-rise stuff we have in Wellington and, obviously, now the Hutt Valley doesn't have one."

The taller appliance also had a "basket" on top of the ladder so three or four people can walk into the basket and be lowered to the ground.

The borrowed appliance didn't have a basket, so rescued members of the public would have to climb out onto the ladder and climb down to the ground, which could be difficult depending on each person's physical capabilities.

The news of the breakdown comes in the midst of what the New Zealand Professional Fire Fighters Union are calling the "Fire Crisis", as they struggle with significant staffing issues across the country.

The Remuera and Botany fire trucks were offline today, and Mt Roskill and St Hellier's trucks were offline yesterday due to these staffing issues.

The union has also claimed that the staffing issues were a factor in a house burning down in Porirua on Friday night.

"A house in Porirua was destroyed by fire overnight. At the same time, one of the Porirua fire trucks had been moved to Wellington City because there were no firefighters," they said.

In a joint statement, the union and Fire and Emergency NZ said they were currently working on a process to "re-engage constructively in collective bargaining".

"A mutually agreed third party will be engaged to support and assist this re-engagement," they said.

"The industrial action currently underway remains in place, but this will not impact our career firefighters' ability to respond to emergency incidents".

Both parties have agreed not to engage in media interviews about the issues to be progressed through the collective bargaining process.