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Despite original materials and techniques being used during the restoration of York Minster's South Transept, there were quite a few small but significant changes made.

Because of the demand for so much seasoned timber to rebuild the vaulted ceiling it was decided to use laminations of dried oak timber.

Although unseasoned timber could be used for the roof structure, the vaulted ceiling relies on tight joints to hold it together.

If unseasoned timber had been used this would have shrunk over time causing joints to become loose with potentially disastrous results.

The carvings on the 68 bosses were originally a simple foliage design, but the Dean at the time decided on something more interesting. So the carvers were each given a theme from the creation of the world and allowed to interpret the verses through their carvings.

That's all except six bosses designed by children for a Blue Peter competition. Designs by Rebecca-Rose Welsh, Richard Gaston, Laura Smith, Ben Kerslake, Tim Hutchinson and Joanna Biggs were selected from the thousands sent in.

There are also six small bosses that are the only pieces of medieval timber to survive the fire and the fall from the roof.

The position of smoke detectors was criticised after the fire and so a new, more sophisticated fire detection system was installed throughout the cathedral. The lightning conductors were also improved.

Finally the vaulted ceiling in the South Transept originally had thin oak boarding between the ribs, like the North Transept. During the fire this burned readily providing tinder dry fuel and helping the fire spread rapidly.

The new ceiling is thick plaster so not only does it look like the rest of the vaults in the cathedral, apart from the North Transept, but plaster is also fire retardent.

The new roof and ceiling structure is compartmentalised so should a fire occur again it will be contained in a small area and be easier to tackle.

Because oak contains a lot of acid, modern stainless steel nails and bolts were used throughout the reconstruction.

A number of hatches are installed on the outside of the roof under the leadwork. In the event of a fire in the roof void, the hatches drop away. Fire fighters would then be able to break through the lead and easily access the fire.