The case of:
'Infected floorboards'

Background:

A large farmhouse was totally refurbished and extended. New floorboards of English air-dried oak, secret nailed, were laid over insulation-about £16,000 worth (big house).

Within eight months scattered holes appeared throughout the floor of the house with 'volcanoes' of frass around each hole. The owner was simply told 'woodworm' had infected boards after laying.

Investigation:

Inspection showed clear evidence of active infestation (insects were actually emerging at the time of the inspection). Holes, frass (flour-like) and beetles were all Lyctus brunneus - powder post beetle.

Three further insects were also found alive in the boards: Ptilinus pectinicornis - male and female (attack sapwood of a limited range of European hardwoods). Forest longhorns (Phymatodes testaceus)- found in part on underside of one board (see photo). A small red forest longhorn also found on the underside of the board. This was Pyrrhidium sanguineum and is reported to have only been found in one place in the United Kingdom; however it is common in Europe.

The longhorn beetles had infected the wood with the bark present long before the floor was laid.

Conclusion:

Lyctus brunneus is highly unlikely to infest susceptible hardwoods in the home (most common origin is storage, and timber yards); the same is true for Ptilinus. Furthermore, in this case insufficient time had elapsed for one life-cycle to complete.

The boards had therefore been infected before supply and laying and, given the nature of the wood, fixing method and structure of the floor, all boards should be lifted and returned to the supplier as not of merchantable quality. The presence of Pyrrhidium did suggest to some extent that the origin of the oak was possibly not English as specified.

[Back to Case Studies page]