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

I'm Eddie Mayer.

Today, the inquiry heard from expert witness Dr Barbara Lane, a specialist in file engineering at Arup,

a global professional services firm specialising in building, design, planning and construction.

At just over 2,000 pages, hers is the longest and most detailed expert witness report.

It focuses on the fire prevention and safety measures in place in the tower on the night of the fire,

and to what extent they failed to control the

spread of flames and smoke.

I think that if those materials had been known, the building shouldn't have been occupied,

because the fire brigade would have then also known what was facing them.

Counsel to the inquiry Kate Grange started Barbara Lane's evidence

by asking about the new windows which were installed as part of the refurbishment

which took place between 2012 and 2016.

Windows were moved out from the original concrete wall

so they could sit flush with the cladding system, which was fitted at the same time.

The windows themselves were reduced in size, leaving a gap of between 30 and 120 millimeters,

between the sides of the windows and the adjacent columns.

Barbara Lane said this range in the size of the gaps was because the original concrete

columns varied in width across the height of the building. To make sure that the smaller windows

fitted, the spaces around them were filled with insulation, known as PIR. There are small pieces of

insulation around each side of the window, trying to fill up the gaps that were formed

...