Assessment of Decay in Timber Beams - An Update

Using a RESISTOGRAPH Decay Detection Drill

The floors at the Archdeaconry at Canterbury Cathedral were being repaired and it was noted once the floorboards had been lifted that there was damage to the beams and floor joists. EBS Ltd was asked to inspect the timbers for Death Watch Beetle and fungal damage including dry rot infestation, wet rot attack and wood worm infestation.

EBS Ltd has recently updated our RESISTOGRAPH decay detection drill.  The new version will allow drilling to a depth of 500mm and give an instant assessment of the condition of the timber tested. This was used to plot the extent of decay in the beams and joists in the floors at the Archdeaconry.

As can be seen from the photographs there was Death Watch Beetle damage to the sapwood of the timbers and they looked to be in poor condition. However on testing the heartwood was found to be sound.  This enabled us to save the majority of the original timbers which initially were thought to be structurally compromised.

EBS Ltd checked the damaged timbers for active Death Watch Beetle and found no larvae in the timbers, which combined with low moisture contents, indicated that the infestation was old and inactive.  Inactive infestations do not need treatment and this saved both the cost of treatment but also the use of toxic chemicals.