Gulf Construction Online - Masa outlines pest management rules

Timber & Plywood

Wooden skirting around walls ... destroyed by termites.

Masa outlines pest management rules

VALENTIN B DIEGO, operations manager with Riyadh-based Masa Establishment for Pest Extermination Services, provides an insight on preventing infestation by non-subterranean termites and other pests that attack the timber and wooden components in buildings.

01 May 2008

Athird of the timber produced worldwide is lost to various biodegrading agents, with termites being one of the major causes of the breakdown in tropical and subtropical conditions and the accompanying heavy losses.

While termites convert deadwood into soil-enriching humus in their natural habitat, they are a potential threat when it comes to timber utilised by man. If the wood is untreated, it cannot offer any natural resistance to the attacks of termite and other wood-boring insects that cause serious damage in building structures.
In addition to termite, several other insects damage wooden building structures and furniture. Many of these, such as the various bark beetles, powder-post beetles and round-and-flat-headed borers are found infesting unseasoned wood and causing serious damage to property.
Powder post beetles, in particular, are extremely destructive causing damage worth millions of dollars to building structures around the world. They infest and re-infest dry seasoned wood, and since the interior of these woods is usually soft sapwood, it is completely riddled with holes or galleries and packed with wood dust. Pinhole openings, often called shot holes, perforate the surface of infested wood.
Timber can be protected from attacks by insects, fungi and marine borers by applying wood preservatives that are usually applied under pressure in order to penetrate deeper and have a longer-lasting effect.
There are a number of measures that should be taken to prevent non-subterranean termite infestation. All lumber should be carefully inspected for evidence of infestation or moisture before being used for construction purposes and infested lumber should be treated. In existing buildings, all doors, windows and other ventilation openings should be screened with 20-mesh non-corrodible metal wire cloth to prevent the entrance of winged termites. Chemically-treated wood and termite-resistant woods can also be used. Attics and wall voids can be slightly dusted with an insecticidal dust such as Drione, to control exploring swarmers. Protection of exterior wood surfaces with an appropriate number of coats of paint is also useful and fill many of the cracks and openings into wood used by termites to gain entrance. Larger cracks and joints can be filled with putty or plastic wood.
Pest management companies are usually most concerned with those insects that damage seasoned lumber. The characteristics of the damage done to wood by these insects are generally sufficient evidence to identify the particular insect family but more positive proof can be obtained upon examination of the insect itself.
Pest treatments for non-subterranean drywood termite infestation can be categorised as extensive infestations, which should be controlled by fumigation where the whole structure requires treatment or heat processes to carry out partial or compartmental treatment; and limited infestations, which is controlled with the direct wood treatment method.
• Structural fumigation, done with sulphuryl fluoride gas (Vikane) as an example, which must be carried out only by experienced professionals as it is dangerous to health. The entire building is covered tightly with a gas-tight cover and the Vikane gas is then introduced. This gas can rapidly and uniformly disperse within the temperature range where drywood termites are usually found.
• Direct wood treatment method, which involves local treatment such as wood injection in building structures. To prepare for the use of liquid aerosol, or dust formulation, holes are drilled into infested timbers through the termite galleries. After this, liquid insecticides such as borates (disodium octaborate tethrahydrate) are poured into these holes. Dusts, such as Drione, should be injected into the termite galleries in small amounts as too much dust will plug the galleries, and the termites will wall-off and these areas will be cut-off from the treatment areas. After an insecticide has been injected into wood, the openings should be plugged with wooden dowels.
Heat fumigation, extreme cold, electrocution and microwaves are other methods of drywood termite control, used on a more limited basis and still in need of further research and development. Consumer preferences, applicator safety, liability, economics and efficiency and effectiveness are consideration for each company in deciding which control methods best suit their needs.
For the heat fumigation treatment method, structures are tarped as they would be for conventional fumigation. Hot air is generated by specialised heaters and blown into the covered structure or a section of the structure until temperatures reaches a constant 140 to 150 deg F. Fans are then used to circulate the heated air and achieve uniform temperature within the area treated. Theoretically, timbers within the treated area should reach 120 deg F and maintained at this temperature for 35 minutes to kill all the termites. Thermocouples, or temperature probes, are used to selectively monitor heated timbers. This can be quite an expensive process in treating an entire building, due to long time taken to achieve the needed temperature. Heat fumigation is a more practical and economical approach for areas of a manageable size which have exposed timbers or where items that may be damaged by heat can be easily removed.
To create extremely cold temperatures of –20 deg F for at least five minutes, liquid nitrogen has been used for localised treatment of termites. Covering the surfaces surrounding the treatment area with insulating mats increases the efficiency of the treatment and reduces condensation. Many variables influence the efficacy of cold treatments and hence further evaluation is required.
The electrocution method by delivering high-voltage and high-frequency electrical energy to targeted sites in timbers, using a handheld unit, is also sometimes carried out. Spot treatments for drywood termites or powder post beetles are implemented by delivering the electric charge to infested wood, thus shocking and killing these pests with the passing current. Drilling holes into wood as well as inserting copper wire into drill holes improves the efficacy of passing the current into infested areas.
Units producing electromagnetic energy at microwave frequencies have also been used on a spot-treatment basis to eliminate drywood termites from structural timbers. The high-energy zone is very limited, so heat-vulnerable items usually do not need to be removed from the structure. However, this distance limitation on microwave transmission means that treatment areas are highly localised so the level of infestation must be precisely identified to achieve control.
Masa Establishment for Pest Extermination Services, a pioneer in pest control and management in Saudi Arabia, has a comprehensive knowledge of the way insects live as well as the safety measures in controlling insect pests, having successfully treated and saved thousands of dwellings, buildings, artwork, museums, antiques, wooden frames and other similar materials made of wood. Its treatment methods are based on 28 years of dedicated service to the public and environment.