Specialist Timber Beam Repair Case Study
Cockington Court
click on pictures for a larger view
Cockington Court is a Grade 2 Listed Building sited on the outskirts of Torquay. Our initial instruction was to upgrade the repairs that had been undertaken in the Victorian era.
It appeared that the beam had been overloaded by the change of use to commercial premises. This had imposed additional weight that had also caused the beam to bend over its full length by 75mm. (Beam size 450mm x 430mm x 7.5 metres.) Due to the large deflection along the length of the beam, a vertical split through the cross section had opened up allowing the beam to drop an additional 75mm.
Over a period of time, the floor joists sections had been repositioned leaving pockets within the beam open. This caused a problem as the pocket depth was on average 160mm deep each side of the beam, leaving just 130mm of solid timber within the central section of the beam. Further problems were that as the beam length distorted the joists were being pulled out of their new pockets.
During investigation of the beam ends it was found that one bearing end had suffered from a severe wet rot attach and had lost almost 60% of timber.
Fissures had opened up along the length of the beam, in parts the length of fissures were 2-4 metres long x 50mm wide and had split into the central section of the beam.
Evidence of insect attack by wood worm Anobium puntatum and Xestopium rufovillosum. Death watch beetle was also evident, although considered a historical attack damage had been created.
Summary:
Split in half
No bearing end
Bent in length
Structurally unstable
Joist not in pockets
Deep fissures
Insect attack
Left: Initial supporting works, also showing flitch plate repairs, probably from the Victorian era.
Right: Supporting works with cracking to the ceiling caused by the deflection of the beam.
Left: After the removal of the outcase boxing. Here we can see the extent of the fissures and where the original joist was sited.
Right: Vertical split through the beam. Note the beam had dropped approx 75mm and that the split was where the pockets of the existing joists were sited.
Left: Detail of the split.
Right: Overall view "bottom side".
Left: Overall view "top side".
Right: The first operation was to drill a series of 35mm holes along the full length of the beam to a depth of 425mm. This beam is oak and very hard.
Left: All the supporting bearing ends were exposed to ensure their structural efficiency. Here one end had suffered from a wet rot attack due to poor maintenance of the roof water discharge system.
Right: Beam end support ready for the cut off.
Left: Opening up the stonework to expose the beam end.
Right: First beam cut.
Right: Bearing end removed
Left: Beam end cut off and lowered onto scaffold platform. Bearing end still located within the stonework.
