Protesters have vowed to lie in front of the bulldozers to save Spanish-mission style cottages set for demolition in St Heliers today.

Save Turua St campaigner Sally Hughes said developer Mike Markham of Anacona Group told the protesters last night the three 1930s cottages will be demolished today.

He advised them to "go home and have a good sleep", she says.

"This only hardened their resolve to protect the houses, which some of the group have been battling for five years to save.

"Protesters are at the houses in Turua street this morning and are prepared to do anything it takes to stop the demolition."

Art Deco Society spokeswoman Dorothy McHattie has spearheaded a campaign to get Auckland Council to place a heritage order on the cottages.

She said protesters were prepared to lie down in front of bulldozers sent to the house or practice civil disobedience.

They want to delay the demolition long enough to explore more legal options to save the houses, she said.

"Today is the lying in front of the bulldozers day.

"Whatever they can do they're going to do it today. That's how much it means to us. We've not been listened to by the Council, we've not been listened to at all."

Auckland Mayor Len Brown said on Monday there is no affordable way to save the cottages from demolition.

He had sought a delay to the demolition after councillors turned down an attempt to place a heritage order on the buildings by a vote of 14-7 on December 16.

"Absolutely everything that could be reasonably and legally done was done in this case, but unfortunately that was not enough."

A letter to councillors from Council Chief Executive Doug McKay said there was no evidential basis to impose or seek heritage orders to protected the buildings.

Buying or shifting the cottages would likely cost in excess of $10m, he said.

"The preferred position is to allow the developer to progress his approved and consented development.

"There is no appetite for spending this amount of money, is the sense I have from feedback to date."