BBC Sounds, Music, Radio, podcasts.

Hello, this is the Grenfell Tower Inquiry podcast reporting every day the inquiry sits.

I'm Eddie Mayer, and today the inquiry started to hear from expert witnesses who've been asked to give their professional opinion on the fire.

We're expecting three of them to give evidence this week.

Today we heard from Professor Jose

Torero. He's a fire safety expert who's been involved in several high-profile investigations,

including the collapse of the World Trade Centre after the September 11th attacks. In his report,

Professor Terrero splits the Grenfell fire into four stages.

Counsel to the inquiry, Kate Grange, introduced them.

So stage one is initiation of the fire event through to breach of the compartment of origin,

which is approximately 0.054 a.m. to 10.m. Stage two is from the breaching of that compartment

of origin to the point when the fire reaches the top of the building on the east face,

approximately 105 a.m. to 130 a.m. Stage three, you characterize as lateral fire spread and internal migration of the fire and smoke until the full compromise of the interior of the building including the stairs and again that's approximately 130 a m to 230 a m and stage four is what you describe as the untenable stage where significant parts of the building are

untenable will come back to this approximately 2.30 a.m. until extinction is the untenable stage. Stage one is

when the fire started and broke out of flat 16 on the fourth floor. Jose Torero explained why this period is so important to understand.

So we make this assumption that the fire will be boxed in within one floor,

even beyond that within one unit.

And on the basis of that, we construct the whole fire safety strategy.

So the primary assumption behind every component of the fire safety strategy remains this

concept of having the fire boxed in within one unit.

So that initial stage represents the period where the building is actually behaving as designed,

where effectively the fire is boxed in within the unit,

...