The original roof is stripped back to the trusses , old tiles are kept to the side incase any gypsies may want to collect them free of charge. The original roof trusses have any bumps planed down and any movement squared up if possible.
From this stage osb boards which were temporarily used as a flooring to build the kit are brought onto the scaffold and used as boards for the roof. any raised nails , dirt or pieces of wood are removed to ensure the roofing felt is not burst.
Once the osb has been fixed down the felt is laid , initially with staples to keep them in position , it is important to ensure a good overlap of 200 - 300 mm is given between sheets as well as excess at the edges to ensure no water can penetrate.
Batons and then counter batons provide a grid to hold down the roofing felt and then hold the roof tiles in place. Different types of roofing require different types of baton with different spacings depending on the way the tile , slate or roofing material is applied.