Many of the floor and ceiling structures contain composite beams, i.e. long beams made of several timber elements joined together with pieces of iron. Defects in two of these beams were identified, one over the Green Writing Room, the other in the North West Tower.
Initial investigation by borescope and fibre optics revealed failures in the beam over the Green Writing Room in need of attention. The beam was accessed through a flat area of ceiling below as the room above has a parquet floor finish. Templates were taken so that steel plates could be made to fit precisely to the shape of the beam and to support the secondary beam connections. Once fitted the ceiling was made good with haired lime plaster and redecorated.
|In the North West Tower access was gained by lifting the lead roof above. The new steel beams were profiled to fit below the existing roofline so that on reinstatement there was no change to the roof level. The work was carried out directly above the Long Library ceiling and so precautions were taken to prevent the risk of damage to the plaster below. These included netting, provision of harnesses for those working above and only using tools with wrist straps. The work was completed to a tight programme.|