The preservation of timber involves additional cost and clearly must be justified. The two main wood destroying agents in building timber are woodboring insects and woodrotting fungi, both, if left to their own devices, will attack and weaken structural timbers, in some cases rendering them unsafe or even destroying them entirely. It will follow therefore that the activities of these insects and fungi should be curtailed on economic, environmental and safety grounds.


The fluids we use are manufactured under stringent quality control. Chemicals used in the formulation of the fluids we apply are those considered most environmentally acceptable and are approved for professional use by the Health and Safety Executive in accordance with the Government’s Presticides Safety Precaution Scheme.

The materials used are suitable for use in situation where protected specifies, such as bats are found.

The fluids are sprayed using a low pressure into the surfaces of the timber. Eggs or insects are killed instantly upon contact with the sprayed material.  The carrying component permeates the timber taking with it the toxic chemicals which are deposited as the carrying component evaporates. The retention aids incorporated in the fluids trap the volatile elements of the chemicals in the timber ensuring a prolonged effectiveness. As the deeper seated larvae tunnel their way to the surface they ingest the toxic deposits and are subsequently killed. Larvae resulting from new attacks are killed when they tunnel into the treated timbers.

Where fungicides are specified fungal growths are killed upon contact and similarly as retention aids hold the toxicity of the material, spores which are deposited later are rendered ineffective.  Care should be taken to avoid roof leaks as these and other damp sources will reduce the effectiveness of the chemicals.  The types of materials to be used will be at our discretion unless otherwise specified.


Joinery treatment will be subject to a separate survey and quotation and is not normally included in our standard structural timber treatment, it cannot be covered by our usual guarantee.



The description “woodworm” is commonly and loosely applied to any of the wood boring insects. In fact, by the time most people are aware of their presence, the metamorphosis, of which the worm or larvae is one form, has completed to the beetle stage.

All wood boring insects commonly occurring in this country have a similar life cycle. The eggs are laid in groups within cracks, crevices and open joints in the wood, these hatch out and the resultant larvae begin tunneling into the timber. The number of eggs laid and the period over which the insect spreads its life in larvae form varies according to the species.  The larvae ultimately pupate and after several weeks in chrysalis form, adult beetles develop and bore their way out of the timber.  Adult beetles live only a short time and will mate during this period and so continue the process.

There are a few natural predators and in consequence with beetles laying between 40 and 80 eggs the spread of the infestation can be fairly rapid.  It will also be understood that the small circular flight holes are only apparent once the beetle has emerged and the observations of a group of these fresh flight holes at one particular point does not necessarily indicate that infestation is only occurring in that one area.  In all probability insects in larva form are also active in apparently unaffected timber. It is, therefore, seldom that localized treatment is effective. The most common types of wood boring insects encountered in structural timbers are :

Common furniture beetle (Anobium punctatum) is perhaps the most prevalent of the woodborers in this country. Its increased attack is attributed to a number of factors such as bulk storage of furniture during the war years and the greater number of older houses with timberwork suitable for its continued survival.  It has a life cycle of between one and four years.

 Death watch beetle (Xestobium rufovillosum) is a larger insect having a life cycle of up to eight years.  It normally attacks hardwoods which have suffered previous fungal decay, hence it is more frequently found in older houses and churches.

The larvae of Death Watch Beetles tend to concentrate their activities at the ends of beams and lintols etc, consequently the results of their labours can often weekend structures to a point where these become unsound.

House longhorn beetle (Hylotrupes bajulus) is fortunately not widespread throughout the British Isles. It causes devastating damage to timbers by tunneling through leaving the external face showing as sound wood and often only by probing can its presence be detected.

Lyctus beetle (Lyctus brunneus and Lyctus linearis) occurs mostly in the sapwood of hardwoods eating the starch in this portion of the wood.  It is sometimes referred to as Powder Post Beetle

Wood weevils (Pentarthrum huttoni Euophryum confine) are very small woodboring insects which will only exist in very damp timber, ground floor skirting boards, basement joists ends etc. They have a life cycle of only a year and the elimination of the damp source will often prevent their survival.

There are a number of other woodboring insects that are brought into this country in imported timber and several which do not adapt to continual attack in converted timber, surviving only in living trees.


Specifications and recommendations


Before effective treatment can take place all dirt must be cleaned from the surface of the timbers and from the lathing surfaces between ceiling joists.

Specifications which do not include thorough cleaning are inadequate.

If proper cleaning is not carried out the sprayed material will be soaked up by dust and dirt. Ceiling lathes usually harbour larvae and unless the deposits of accumulated dirt are taken off, the method by which the material works cannot be fully effective.  Cobwebs too will act as a screen and hold the sprayed material, preventing it from reaching affected surfaces.

It therefore follows that thorough cleaning should take place.  This work can be carried out by the client if required.

Decorated timber surfaces:

Where timbers are limewashed, painted, varnished or similarly decorated, the penetration of fluid is inhibited by the impervious nature of these decorative surfaces. Limewashed surfaces must be wire brushed to expose a sound and firm surface.  Paint and varnish should be removed by a heat application or paint stripper.Our quotations do not allow for this work which should be carried out prior to our attendance.

In some instances painted joinery can be protected, particularly from wet rot attack by drilling and injecting using a plastic valve insert however generally, joinery will not be treated.

Beams and heavier sectioned timbers:

Where considered necessary, the heavier section members will be drilled and a plastic valve inserted and insecticidal/fungicidal solution injected, a penetrating wood preservative paste will be applied to vulnerable areas, particularly beam ends.


Timbers with chamber riddled sapwood edges are often attacked to an extent where they are reduced to a fragile “honeycomb”, this is referred to as “frass” and should be trimmed back using a adze or similar device to a sound timber surface.


Most modern composite building boards are insect proof.  However prior to the development of synthetic adhesives  most plywoods were fabricated employing the use of animal glues which often attract woodboring insects.  Due to the impervious nature of the glues penetration by insecticide/fungicide fluid is inhibited, therefore, it is recommended that badly affected panes are replaced by the client.

Access to hidden timbers:

As far as practicable all hidden timber structural members such as wall plates and boards supporting parapet gutters, should be exposed and treated.  If the roof is being refelted or tiled it is recommended that our service is incorporated as part of the roofing contract and carried out simultaneously.  Floorboards are normally taken up at about one metre intervals (every fifth or sixth board), thus allowing access for cleaning and treating.

Thermal insulation:

Where thermal insulation is laid, to ensure full and effective treatment this must be removed. Where rye husks or vermiculite have bene used this can be expensive and laborious, nevertheless this is the only method by which successful eradication can be effected.  Glassfibre quilt should not be laid prior to treatment taking place, care will need to be exercised where the use of solvent borne materials have been used.

Fire hazards:

We recommend and use water borne materials thus minimizing the risks.

Protection and safety by Timber Decay Treatment Limited

Our work is carried out in accordance with Government C.O.S.H.H. regulations.

By the client:

Areas where food storage is involved require particular attention and should be emptied before and left well ventilated after treatment.

Children and pets should be kept away from treated areas for 48 hours. The client should remove fish tanks from treatment area and ventilate treated areas thoroughly.

There are a number of wood boring insects that can cause problems in your home. All types of woodworm have very similar life cycles. Woodworm can spread rapidly if left untreated as the eggs are laid in groups within the cracks & crevices of the open joints in the wood, when these hatch the larvae tunnel into the timer where they pupate and after several weeks, adult beetles develop and bore their way out of the timber. Adult beetles will then mate in the short period they are alive and so the process continues.

Here at TDT we have a great selection of treatment methods and solutions to remove woodworm. All our treatments are environmentally friendly and have the latest HSE accreditation.

CALL TDT PRESERVATION – 01761 416 728 


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