Timber and pest Advice – a technical guide

What to do:

• attempt to locate the nest and destroy the nest if found;
• if the nest cannot be found, attempt destruction of a remote colony with careful application of poisonous dust that should be carried back to the nest;
• judicious use of chemical barrier treatment if considered necessary.

If the Pre-Purchase Property and Timber Pest Inspection Report identifies termite damage, engage your Building and Timber Pest Consultant to determine the full extent of damage and need for repairs (including investigation of concealed structural timbers where appropriate) and undertake repair works. When structural damage occurs, repairs can be complicated and costly. The extent of damage can only be determined by opening up the building fabric. If such repairs require people to work in a confined area, such as a sub-floor, that is to be chemically treated (i.e. barrier treatment), it is recommended that repairs are completed before any chemical treatment. In cases where chemical treatment precedes repair works, wearing appropriate protective clothing and equipment (including respirator) and the time delay between treatment and building works is advised (consult your pest controller/consultant about the timing treatment and repairs).

• Obtain access to all inaccessible areas
• remove timber debris from the sub-floor area.
• Remove unnecessary form-work timbers, especially those in contact with the ground in the sub-floor area.
• Remove (or monitor) dead trees or tree stumps near the house.
• Store firewood up off the ground, undercover and preferably away from the building
• avoid long term storage of building timbers in contact with the ground.
• Untreated hardwoods used in landscaping (e.g. sleeper retaining walls, hardwood garden edging) are prone to decay, and termite harbourage
• replace with treated pine or masonry or regularly monitor for signs of increased timber pest activity.
• Avoid tree roots entering sub-floor area as these can provide access for termites.
• Timbers penetrating ground (e.g. pergola posts, door jambs, steps stringers) can offer points to concealed termite entry to attached structures.   Alter to avoid direct contact with the ground, eg installation of metal stirrups.
• Where the base of exterior wall cladding (e.g. weatherboards) are in contact with ground (paving, soil, etc.) decay damage is likely and concealed termite entry is possible. Alter to avoid such contact.
• Keep exterior perimeter of concrete slab edges clear of weeds, built-up garden beds, raised paving levels etc so as to avoid concealed termite entry over slab edge and into wall (and possibly roof) frame timbers
• prevent excessive moisture in and around sub-floor areas, e.g. maintain proper ventilation and avoid entry of stormwater, rectify any leaks in water and drainage pipes. Check regularly for leaks under sinks, taps and refrigerators.

• Standard inspection procedures cannot determine whether or not the borers are still active. The most practical method for determining activity status is to monitor damage levels. Try to establish whether any new holes are appearing over time (in the case of floorboards, for example, square off a few sections of the underneath of the boards with carpenter’s pencil or texta and circle all of the emergence or exit holes). If the beetle infestation is still active, new holes will likely appear each spring (usually October-November). Re-examine each year for signs of new activity.
• Infestations of furniture beetle in old pine flooring may, over many years, result in such severe damage that floor replacement is required. In other cases, the cost remains at minor to moderate levels and activity may have ceased. In such cases, only occasional boards may require strengthening/replacement. (A Building Consultant can advise on the extent of structural damage and need for repairs).
• Where the borers appear to be existing invaluable furniture (such as antiques), consider having the article(s) fumigated by a company that carries out such work: the process of fumigation usually uses non-residual poisonous gases that do not protect against future infestation.
• Where only a few shelf timbers show furniture beetle damage, it is advisable to properly dispose of damaged timber and replace with resistant timber species (hence lessening the chances of an infestation developing in furniture if the activity was present in the shelf timbers)
• Minor damage levels to floorboards do not affect structural strength but may become visible if floors are sanded/polished.
• Replace severely damaged timbers with a suitable Anobium resistant wood such as Cypress Pine or any hardwood species such as Brush Box or Tallowwood.
• Replacement of infested timber is the preferred method of reducing further infestation. Chemical spray treatments are sometimes considered unreliable (mainly because the grubs reside well within the timber and surface sprays may not be fully effective). Note: In cases where replacement is not feasible, consultation with a Pest Control Consultant may find a chemical strategy that is appropriate (by careful timing of treatments and modified application techniques, for example).
• Sub-floor areas with higher moisture levels are favourable to the development of these borers. Consider improving sub-floor ventilation.
• Always check incoming furniture (particularly older furniture/antiques) for signs of Anobium borer damage (symptoms are small round holes containing gritty frass – ‘borer dust’) as this may facilitate a new infestation.

2.3.2 Powderpost beetle (Lyctus brunneus )

This small beetle attacks only the sapwood section of certain species of hardwood timber. It prefers recently seasoned timbers and is unlikely to be active in timbers that are more than about 15 years old. Evidence of Lyctus damage is often encountered in hardwood floor frame and roof frame timbers. However, it usually involves only a corner or edge of the timber (showing small round holes and fine frass or ‘borer dust’) and very rarely presents a structural problem.

Although possibly active in newer buildings, it is unlikely to cause any severe damage as it only attacks the sapwood section of timber (and the Timber Marketing Act regulates the amount of sapwood in building timbers in NSW). If more than 25 per cent of the perimeter of structural timbers appears to be affected, (or signs of Lyctus damage become evident on manufactured or moulded items such as doors or architraves), then an infringement of the Act may have occurred. Complaints may be lodged within 24 months of purchase of the timber material.  For enquiries contact the Forestry Commission of NSW. Stiffen or replace any severely affected timbers.

2.3.3 Timber defects caused by forest insect pests

Damage caused by forest timber pests is inactive and presents no threat to the building structure.  Such damage may appear as small to large, oval or round holes or tunnels – sometimes filled with grass if caused by moths or beetles or it may seem as hollow grooves if caused by termites.