Three Irish women who were renting the Berkeley apartment where a balcony collapsed last summer, killing six people and injuring seven others, are suing the property owners and managers for damages.

In legal papers filed recently in a California court, the three say they stepped off the balcony "just before" it collapsed and suffered "severe mental and emotional harm" as a result.

The three are named as Caroline Mary Conlan, Cliodhna Clare Maloney and Aisling Mary Tallon in papers filed to the Superior Court of California in Alameda County.

The women were the tenants of apartment 405 Library Gardens and legal papers show they had rented it just two weeks before the tragedy occurred.

They are suing 11 named defendants who fall under the umbrella of two companies: Blackrock - the owners of the Library Gardens development, and Greystar - the property managers.

However, the women have reserved the right to add others to the case as it proceeds.

The three are alleging that the wooden deck of the balcony was already water damaged before the water-proof coating was applied in 2006, during the construction of the Library Gardens complex, and that the owners and managers knew it was dangerous.

In the legal document, the three say that they believed their own lives were "in grave peril", and having "seen, heard and felt the collapse of the balcony, followed by seeing and hearing their dearest friends plummet to the ground below", they suffered "severe emotional and mental injuries from which they have not recovered".

They are claiming that their "injuries, damages, losses and harms" would not have happened if the Blackrock and Greystar companies had "complied with the standard of care in their professions, not cut corners", and paid attention to "at least one of the numerous red flag warning signs that the balcony was unsafe".

The three Irish women say that "only by the grace of God" were they not on the balcony at the time and after witnessing the collapse they "looked down in horror at the heap of bodies and rotted balcony lying on the ground 40 feet below".

Eimear Walsh, Olivia Burke, Ashley Donohoe, Eoghan Culligan, Lorcán Miller, and Niccolai Schuster all lost their lives when the fourth floor balcony collapsed beneath them.

Aoife Beary, Hannah Waters, Clodagh Cogley, Sean Fahey, Conor Flynn, Jack Halpin and Niall Murray were all injured.

The plaintiffs claim that the companies being sued knew the balcony was dangerous because there had been earlier reports of mushrooms growing on the deck, and at least a year before the tragedy there were reports of the balcony tilted away from the building.

Ms Conlan, Ms Maloney and Ms Tallon are alleging that the group of companies "acted in a manner that was despicable and malicious", with a "wilful and conscious disregard of the rights and safety of others".

It is alleged the companies subjected the three women to "cruel and unjust hardship in conscious disregard of their rights, including the shock, terror and irreparable emotional and mental anguish" they suffered.

The "sustained mental and emotional injuries" the three friends suffered are described as including "stress, anxiety, depression, paranoia, worry, discomfort, fear, and sadness".

They are seeking damages to cover the expenses incurred for their medical care and treatment so far, and will into the future, as well as the costs they bore in finding alternative accommodation when they were evacuated from the apartment and the damage to their belongings.

The three also said their future earning capacities have been "compromised and damaged".

In addition to the damages that they feel they are immediately owed, they have also asked the court to impose "punitive and exemplary damages" on the companies involved to sufficiently "punish" them and to "make an example of them so as to deter future conduct".

The legal documents outline for the first time more detail about the allegations surrounding the cause of the collapse.

Following an investigation, the District Attorney for Alameda County decided not to pursue criminal manslaughter charges against any one individual or entity, but did conclude that water had been trapped in the deck during the construction phase which had led to "eventual and extensive dry rot damage".

In the legal filming from lawyers representing the three Irish women, they claim that although the balcony deck was constructed in October 2005, the waterproof coating was not applied until January 2006 at the earliest.

During this time the uncompleted balcony, the women say, was "exposed to harsh and wet conditions, including extensive rainfall". 

They say that in the two months after the wooden deck was laid there were 21 days of rain in California, where a total of "13 inches" (33cm) of rain fell.

In addition, they claim the building specifications called for plywood but that the contractors and subcontractors installed a cheaper option, installing three layers of "oriented strand board" - a material that is more susceptible to water damage.

This cheaper substance became "saturated with rain and moisture" during the time it was exposed, and yet they claim, the waterproofing substance was applied anyway because "it would have been costly, difficult, embarrassing and inconvenient to repair and rebuild the balcony in a safe and reasonable manner" and that it would have delayed completion of the project.

Completing the waterproofing "created a concealed and hidden trap" and the three allege that the companies knew the balcony construction was "dangerous and contrary to safe and accepted construction industry standards".

They claim that the Blackrock and Greystar companies knew of the dangers posed and yet "consciously chose to take no action", behaviour they described as "outrageous".