Around 30 witnesses will be called to give evidence to Coroner Suzanne Anderson at Omagh Courthouse and three days have been set aside for the proceedings.
36-year-old Arthur McElhill, his 29-year-old partner, Lorraine McGovern, and their five children, Caroline, 13, Sean, 7, Bellina, 4, Clodagh, 19 months, and James, nine months, all died from smoke inhalation in the fire at their home at Lammy Crescent in November 2007.
Last year the PSNI revealed that an accelerant had been used to start the fire.
Caroline had made a 999 call for help just before the house went up in flames. She was found dead in an upstairs room clutching a telephone in one hand and a set of rosary beads in the other.
Lorraine McGovern's family were clearly distressed in court after hearing a recording of her eldest child making a frantic telephone call for help from the house as the fire began to spread.
The McGoverns and the family of Arthur McElhill sat separately in court. They had been given a chance to hear the recording of the 999 call before the proceedings started, because of its graphic nature.
Lorraine McGovern and the five children were buried together in Co Cavan while Arthur McElhill was buried separately in Ederney, Co Fermanagh, where he once lived.
A forensic scientist from Belfast said he believed the fire had been caused by the ignition of petrol and white spirit in the hallway of the house near the foot of the stairs.
He said it was most likely to have involved an occupant of the dwelling, because it was secure. Both he and another forensic expert ruled out the possibility that the fire had been started by someone pouring petrol through the letterbox.
Two policemen told the coroner how the house was well ablaze when they arrived at the scene, followed by the fire service.
The inquest also heard how two neighbours had brought a ladder and tried in vain to rescue the occupants, but were beaten back by the flames and smoke.
Layers for Arthur McElhill's relatives intend to challenge aspects of the inquest. The coroner therefore decided to hear the non-contentious witnesses today and tomorrow.
In May, the Public Prosecution Service said there would be no prosecutions in relation to the incident.
It is expected that members of the McElhill and McGovern families will be called to give evidence at the inquest and anyone who had dealings with the victims before the incident.
Neighbours, particularly those who tried to get the family out of the blaze, will also be called as will members of the medical and emergency services.
It was revealed after the fire that Mr McElhill was a registered sex offender.
An independent inquiry last year found failings within Social Services.
A report criticised how information was communicated within the Western Health and Social Care Trust and other agencies and the assessment of potential risks posed by Mr McElhill to teenage girls.
The report had 63 recommendations and the North's Health Minister Michael McGimpsey said they would be implemented and that child protection services across Northern Ireland would also be inspected.
