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Insects that attack timbers do so mostly in forest and
woodland habitats. We fill our
properties with timbers as a building material and effectively lay out the
insect’s food material in extensive amounts (joists, floorboards, joinery and roof
timbers) available for insects to infest. We
encourage attack further by placing these timbers in areas where dampness can
occur e.g. ground floors and roofs, and sometimes in areas where leakage of water
onto local timbers can occur too e.g. bathrooms and kitchens. However, timbers do not necessarily need to be damp to
become infested.
Pre-treatment of timbers with insecticide will prevent
infestation but in older properties treated timbers have not usually been used
in the original building. Design
features of older buildings might encourage dampness to occur and insect
infestation in these older properties is not unusual.
Treatment/replacement of timbers requires specialist
advice to ensure the correct treatment is given (some insect attacks do not need
chemical treatments), and this relies on correct identification of the infesting
insect.
The most common insect attack is by wood boring beetles. These are insects
that rely on timber as a food source. Where beetles attack timbers, the usual
description of the attack is described as "woodworm". This is because
the larvae of the beetle looks like small cream-coloured worms. It is the larvae
that do the bulk of the damage to the timbers.
Use of insecticides is governed by Acts of Parliament (law)
and Health and Safety Regulations and this requires specialist knowledge. Timber replacement must follow existing Building Regulations and
guidelines to make sure that the timbers can perform structurally to
specification.
Assessment
Our work to deal with insect attack to timbers always
starts with a visit to site to inspect the problem. Sometimes no treatments are recommended, either because the
infesting insect does
no structural damage or because an infestation looks old. There is always the strong possibility that a past treatment has already
successfully been undertaken. Surveyors
and companies are not allowed by law (Control of Pesticides Regulations 1986) to recommend unnecessary timber treatments
and must justify clearly any use of insecticides.
Tests for already treated timbers can be carried out. A flame (Beilstein)
test will determine the presence of halogenated materials in timber. This
would detect, for example, the use of an organo-chlorine insecticide.
These were used in the past as insect treatments, but are now only used by
qualified people under the direction of qualified surveyors. They have been
replaced by the permetherin and boron insecticides. Tests for the newer
insecticides are also possible and material needs to be sent away to a
laboratory for this. We are able to arrange for these tests to be
undertaken. We charge for this service.
Determining if an infestation is active is difficult. It is not sufficient
just to see woodworm holes or to detect frass falling from the timbers. Once the
woodworm holes are there they never go away and frass can be dislodged from
timbers years after a successful treatment. However, these are both indications
of a potential problem, which is why you need expert advice.
The flight season of woodworm is in the warmer months of May to September,
with a narrower range (say June to August) in more northern areas. The best
proof of an active infestation is to see live beetles or to find them dead on
window ledges or other surfaces. You will need an expert to identify them, as
they can be confused with the many species of carpet and other beetles that live
in our properties. They are attracted to light and tend to be drawn to lighter
coloured surfaces and windows. Real evidence of an infestation should be gained
before deciding to treat. Why spend money on treatments that have already been
successful ? The treatments may also still be under guarantee from the company
who did the work. Such guarantees are usually in
force for between 20 and 30 years.
Treatment
Where a treatment is recommended/required then this is
usually a liquid insecticide applied by coarse spray directly onto the
timber’s surface. An alternative
is the use of gels or pastes often applied close to inaccessible timbers (e.g.
joist ends) with the ability of the compounds to diffuse into the inaccessible
timber. Various chemicals are presently in use and include permetherin (a
synthetic pyrethroid), boron (a naturally occurring mineral compound) and a
relatively new group of chemicals which inhibit normal insect development
(growth regulators). Our company
primarily uses permetherin, offering boron as an option where there are health,
safety and/or environmental considerations.
Spray treatment to timbers is a relatively easy process,
but is disrupting to the property occupants as everything (carpets, other floor
coverings, furniture, fixings and etc.) has to be moved, or movable, to gain
access to the surface of the timbers to be treated. After spraying Health and Safety regulations requires
the minimum of 8 hours to elapse and surfaces to be dry before re-entry to a
treated area and its reinstatement to habitable use. There are insecticides now available where a 1 hour re-entry has been granted, but this is
still dependant on the timber being dry as well. Drying out is unlikely to be
that fast unless it is forced. We prefer to consider the 8 hour "rule"
as being the one to apply.
Recent reformulation of timber treatment fluids for woodworm now means that
they are virtually odour free. Some slight smell may be noticed immediately
after treatment, but this quickly declines with drying and improved ventilation.
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