Preservation ~ ref. Building Regulations: Materials and
Workmanship. Approved Document to support Regulation 7.
Woodworm infestation of untreated structural timbers is common.
However, the smaller woodborers such as the abundant Furniture
beetle are controllable. It is the threat of considerable damage
potential from the House Longhorn beetle that has forced many
local authorities in Surrey and the fringe areas of adjacent
counties to seek timber preservation listing in the Building
Regulations (see Table 1 in the above reference). Prior to the
introduction of pretreated timber (c. 1960s), the House Longhorn
beetle was once prolific in housing in the south of England,
establishing a reputation for destroying structural roof timbers,
particularly in the Camberley area.
House Longhorn beetle data:-
Latin name † Hylotrupes bajulus
Life cycle † Mature beetle lays up to 200 eggs on rough surface
of untreated timber.
After 2-3 weeks, larvae emerge and bore into wood,
preferring sapwood to denser growth areas. Up to 10
years in the damaging larval stage. In 3 weeks, larvae
change to chrysalis to emerge as mature beetles in
summer to reproduce.
Timber appearance † powdery deposits (frass) on the surface and
the obvious mature beetle flight holes.
Beetle appearence †
Other woodborers:-
Furniture beetle † dark brown, 6†8 mm long, lays 20†50 eggs on
soft or hardwoods. Bore holes only 1†2 mm diameter.
Lyctus powder post beetle † reddish brown, 10†15 mm long, lays
70†200 eggs on sapwood of new hardwood. Bore holes only
1†2 mm in diameter.
Death Watch beetle † dark brown, sometimes speckled in lighter
shades. Lays 40†80 eggs on hardwood. Known for preferring the
oak timbers used in old churches and similar buildings.
Bore holes about 3 mm diameter.
Timber Roofs---Preservation