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How Do I Kill Woodworm? A SkilledBuild Guide to Woodworm Killer...

What does Woodworm Killer treat?

How do I kill woodworm?  The answer is SkilledBuild Woodworm Killer.  The product is a professional grade concentrated insecticide based on the well proven and low toxicity insecticide Permethrin.  It is designed to eradicate and prevent re-emergence of woodworm - Common Furniture Beetle (Anobium punctatum) and Death Watch Beetle and other wood boring insects and beetles and weevil.  Treatment benefits include immediate relief by eliminating active insects as well as penetrate into wood to provide long term residual protection. 


                                 Common Furniture Beetle                         Death Watch Beetle                     Wood boring weevil                      House Longhorn Beetle

                                 Common Furniture Beetle                               Death Watch Beetle                              Wood Boring Weevil                                   House Longhorn Beetle



                                                       Key Benefits

 - Long term (20 year +) residual protection against woodworm and all boring insects, beetles & larvae     

 - Kills insects and beetles on contact.

 - Good penetration, 0.2%w/w Permethrin on dillution.

 - Use new and old timbers of all types.

 - Water based, low odour. Non flammable.

 - Listed by Natural England for use in bat roosts.

 - Ease and safe application. HSE 1 hour re-entry approved.

 - Effective on woodworm and insects and beetles.

 - Very cost effective and no specialist equipment required. 


How Do I Apply Woodworm Killer treatment?


1. Ensure all timber surfaces are adequately exposed and clean (vacuuming preferred) and free from previously applied paint coatings, varnishes etc. and are in a condition which allows the treatment to penetrate successfully. Pull back loft insulation to fully expose joists and timbers.  Where practical, sealed voids and boxing should have openings made to enable through spraying all timbers within. (Allow treatments in voids to fully dry before re-sealing)

2. Where there are signs of previous infestation of woodworm, or Death Watch Beetle, or woodboring beetles, or other wood boring insects a full structural assessment may be necessary to determine if any timbers are so badly decayed that they require replacement before treatment of other timbers is carried out.


3. The product is supplied as a concentrate to be diluted with water by adding 1 litre of Woodworm Killer to 24 litres of water to yield 25 litres of ready to use Woodworm Killer.

4. Once diluted, please ensure that drums of the ready to use product are suitably labelled during use and storage.

5. Where applicable, notify occupants of adjoining properties before treatment commences.

6. Agitate the diluted product before use.

7. Apply the diluted product by either brush or low pressure spray giving a course droplet (low pressure: 210-350kPa, 30-50 Ibs/in2).

8. The timber should be saturated to refusal, paying particular attention to areas displaying insect emergence (i.e. small holes). Exposed end grains, reverse of stair boards and sub floor joists must be exposed to allow sufficient access for adequate effective treatment.  Ensure that all exposed faces of the timbers and are fully treated including those hard to access areas.  Invariably application will require a combination of both spraying and manual brushing to achieve best application.

9. Rough sawn timbers are easier to treat as they retain greater volumes of treatment due to their rough surface.  Smooth and planned timbers or those where the treatment appears to ‘run off’ the surface may be best treated by two or more light spraying passes, allowing the treatment to be absorbed between each spraying.

10. The effectiveness of the treatment may be reduced if timbers are subjected to high humidity or condensation or affected by water, such as may occur through roof or pipe leaks.  In these instances the affected timbers should be re treated with Woodworm Killer or N-Virobor 20, after the cause of the ingress has been rectified.

Areas of typical timber treatment

- Furniture.

- Doors, frames & architraves.

- Window Frames.

- Roof Timbers.

- Floor Boards.

- Joists.

- Rafters.

- External and Internal Use.

What other products are available to treat Woodworm? 

When assessing which product to use, we recommend you look at the other products in the SkilledBuild timber treatment range.  Typically the best treatment strategy will require more than one type of product.  A number of products in the range provide a dual protection against both insect and fungal rot.  Other products to consider include:

SkilledBuild Dual             

This concentrated wood preservative protects timber from dry and wet rot as well as preventing and eradicating wood boring insects (woodworm) during the drying out period after the removal of damp. It should be sprayed on all timber which is at risk from insect attack or dry rot.

Sold in concentrated 1 litre container to make 25 litres usable product. Product Code N05010.

SkilledBuild N-Virobor 10

This water based (aqueous) product is universal in that it acts as a timber preserver for eradication of woodworm and other wood destroying insects, as well as protecting against dry rot and other timber rotting fungi.  The product may also be used as an effective masonry biocide for irrigation of stone and masonry walls. 

Can be applied by either brush or spray. It is suitable for the treatment of all dry timbers as part of an insect and dry rot and wet rot control strategy.

It is suitable for smaller dimension timbers (up to 19mm x 38mm or ¾” x 1 ½”).

Sold in 5 litre containers – Ready To Use.  Products Code N05001

SkilledBuild N-Virobor 20

This brushable/ injectable, wood preservative gel offers maximum protection against dry and wet rot as well as attack by wood destroying insects such as woodworm and beetles.

N-Virobor 20 is ideal for larger dimension timbers (over 19mm x 38mm) as the active ingredients migrate deep into the timber.  Active ingredients achieve improved penetration deep into timber which is damp.

Sold in 1 litre injection cartridge and 5 litre containers – Ready To Use. 

Product Code 

N05002 - N-Virobor 20 1L

N05003 - N-Virobor 20 5L

Dual Woodworm Killer                   NVirobor 10                         NVirobor 20     

       SkilledBuild Dual                                             N-Virobor 10                                                  N-Virobor 20



                                                         Product Data   

Storage: The product should be stored in a cool dry place.


Coarse Spray: 1litre to 3-4m2.

1 litre pack diluted to 25 litres with water covers a maximum of 100m2.

4 x 1 litre packs treats the roof void of a typical 3 bedroom semi-detached house

                          Woodworm Killer

 Health & Safety:

- Irritating to eyes. May cause sensitisation by skin contact.

- Very toxic to aquatic organisms. May cause long term adverse effects in the aquatic environment.

- Wash hands and exposed skin before meals and after use. Wash any contamination from skin or eyes immediately.

- Keep only in the original container. Keep container tightly closed. Keep in a safe place. Keep out of reach of children.

- If swallowed, seek medical advice immediately and show this label or container.

- Ensure adequate ventilation before reoccupation.

- To avoid risks to man and the environment, comply with the instructions for use.


- FOR USE ONLY BY PROFESSIONAL OPERATORS. The (COSHH) Control of Substances Hazardous to Health Regulations 2002 may apply to the use of this product at work. Engineering control of operator exposure must be used where reasonably practicable in addition to the following items of personal protective equipment.

- WEAR SUITABLE PROTECTIVE CLOTHING - coveralls and synthetic rubber/pvc gloves and face/eye protection when diluting and using.

- DO NOT BREATHE SPRAY MIST. Otherwise wear respiratory protective equipment and eye protection (see HSE Guidance Booklet HS (G): ‘Respiratory Protective Equipment – a practical guide for users’).

- Avoid excessive contamination of coveralls and launder regularly. However engineering controls may replace personal protective equipment if a COSHH assessment shows they provide an equal or higher standard of protection. 

- Do not contaminate foodstuffs, eating utensils or food contact surfaces. This material and its container must be disposed of in a safe way.

- Wear suitable eye/face protection (including when diluting).  Avoid contact with skin.  Avoid contact with eyes.  In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. Do not empty into drains.

- Exclude ALL unprotected persons and animals during treatment and for at least 1 hour after treatment is completed.  Ensure there is a physical barrier to prevent contact by unprotected persons and animals until the surfaces are        visibly dry.

- All BATS are protected under the Wildlife and Countryside Act 1981.  Before treating any structure used by bats, consult Natural England, Scottish Natural Heritage or the Countryside Council for Wales. 

- Cover water storage tanks before application.

- Do not contaminate ground, waterbodies or watercourses with chemicals or used containers.  Remove or cover all fish tanks and bowls before application.         

- Read All Precautions Before Use. HSE No. 8570.


Important Information  

SkilledBuild is committed to development and supply of quality products and may substitute or change product branding or specification or technical data without notice.  Always check for latest information.

All information provided is based on practical tests & published data and is intended to guide a competent DIY user or contractor in the typical use of products for minor works but is without guarantee.  If a failure of the works will be costly to repair or hazardous then design & execution must be undertaken by competent persons.   Further advice should be sort from a suitably qualified advisor.  Skilled Build may be able to answer simple product enquiries. 

Since application and working and user competence is beyond our control, no liability of the supplier can be derived from the contents of information sheets or other general information provided.  Any statements made beyond the contents of SkilledBuild’s website or product labels must be confirmed in writing by the supplier.