This treatment is applied to existing buildings which have already been attacked by termites. Even after their entry in the building the termites maintain regular contact with their nest in the ground. This important symptom is gainfully utilized in eradicating termites from the buildings. Regular inspection and suitable control measures are necessary to prevent damage to buildings from termites. At times when the termites attack is of minor nature it may only be necessary to break off the shelter tube to check the damage from termites. In situations where the attack is of mild nature the effected materials may also be removed along with shelter tubes. In case of severe attack it is necessary to poison the soil around and beneath the building besides resorting to the above steps. Thus the type of treatment to be given to eradicate termites from the existing building will largely depend upon the extent of attack and the magnitude of cellulosic and other materials available in the building. The operations involved in termite eradication are
Inspection
Inspection is carried out to estimate the magnitude of spread of the termite’s infestation in the building and also to detect the root of the entry of termites and the zones in the building which are attacked. The portion of the building in contact or adjacent to the earth should be inspected first. This includes basements, ground floor, steps leading from ground, walls, columns, areas having damp or humid conditions like bathrooms, lavatories, leaking pipes or drains etc. and the places where wood work is embedded in the floor or wall. The ceilings, wooden paneling, battens for wiring, conduits , switch boards are other locations which serve as hide-out for the termites and need careful inspection.
In case of multi-storied buildings, lifts , wells , casings and coverings of electrical wiring, telephone cable, water supply and soil pipes which serves as convenient and well protected zones for termites infestation should also be inspected carefully.
Wherever the mud walled shelter tubes or the termites run away are detected they should be removed. Wherever possible, oil or kerosene based chemical emulsion should be injected over the attacked areas of wood work and masonry. At times structural additions may become necessary to ensure elimination of all direct contacts between the soil and the effected portion of the structures.
Soil treatment for foundations
This treatment consists in treating the soil under the building and around the foundations with the chemical emulsion that can kill or repel termites. In this treatment about 500 mm deep trenches are made along the external peripheral wall of the buildings with the help of shovel (width of the trench being equal to the width of the shovel) and 12 mm dia to 18 mm dia holes at 150 mm centers are then made in the trenches close to the wall face with the help of iron rod. The holes should preferably extend up to the top of footing of foundations or to a depth of at least 500 mm whichever is lesser. The holes are then filled with chemical emulsion in water and the back fill earth is also sprayed with chemical emulsion as it is returned to the trench thereby creating a barrier of poisoned soil along the external periphery of the buildings. The total quantity of the chemical to be used in this treatment should be at the rate of 7.5 liters per sq. meter of the vertical surface of the masonry in foundation.
In case of RCC frame structure, the chemical treatment shall be applied to the soil in contact with column sides and plinth beams along external periphery of the building for a depth of 500 mm below ground level.
In case the building has masonry or concrete apron, about 12 mm dia holes at 300 mm centers shall be drilled close to the plinth wall along the apron. The holes should be deep enough to reach the soil below. Chemical emulsion should thereafter be pumped into these holes at the rate of 2.5 liters per linear meter of the length of the apron.
Soil treatment under floor
Cracks in floors are the weak spots which permit entry of termites from soil below the floor. The cracks usually occur at the junction of the floor and walls, expansion joints in floor and at construction joints in a concrete floor. Cracks in floors may also develop due to use of unsound materials or on account of defective workmanship. In such cases eradication of termites is achieved by poisoning the soil underneath the floors wherever such cracks are noticed. This operation is generally carried out by drilling 12 mm dia holes till the soil below gets fully saturated. The maximum quantity of chemical emulsion may however, should not exceeds one liter per hole. The holes in floors are sealed after treatment.
Treatment of voids in masonry
Termites enter into masonry foundations from soil adjacent or beneath the building and work their way up through voids in masonry joints and gain entry into the interior of the buildings. To prevent the entry of the termites through voids in masonry, 12 mm dia holes at 300 mm center to center are drilled at downward angle of about 450 from both sides of walls at plinth level and then chemical emulsion is pumped into the holes until masonry gets fully saturated with the chemical emulsion. The holes are then sealed. This treatment is carried out for all walls having foundation in soil. Treatment of drilling hole and pumping chemical emulsion shall also be carried out at critical locations like wall corners and at places where door and window frames are embedded in masonry in ground floor.
Treatment of wood work
Wood work which is badly damaged by termites should be replaced by new timber which is adequately brushed or dipped in oil or kerosene based chemical emulsion. The infested wood work for door and window frames, etc. should be given protective treatment by drilling 6 mm dia holes at 150mm center to center at a downward angle of 45 o to cover the entire framework and thereafter pumping oil based chemical emulsion into the holes. The wood work which is not attacked by termites should be sprayed over with chemical emulsion to prevent possible attack.
Last modified: Wednesday, 29 February 2012, 12:00 PM
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