A guide to timber treatment.

Professional timber treatment isn't just about a quick spray; it is a systematic process to identify moisture sources, eradicate infestations, and protect the structural integrity of your property for decades to come.

What Does the Work Involve?

• Site Survey: Using moisture meters and visual inspections to identify the type of fungal decay or insect infestation.
• Preparation: Removing floorboards, plaster, or loft insulation to access the affected timbers.
• Cleaning: Wire-brushing timbers to remove dust, debris, and loose wood fibres so treatments can penetrate deeply.
• Chemical Application: Applying fungicidal or insecticidal fluids via high-pressure spray, brush, or targeted injection.
• Timber Replacement: Cutting out "beyond repair" sections and splicing in new, pre-treated timber using "sistering" or bolt-on techniques.
• Environmental Control: Addressing the root cause, such as fixing a leaking pipe or improving sub-floor ventilation.

Typical Costs

Prices for timber treatment vary significantly based on the scale of the infestation and whether structural repairs are required. All prices below include VAT at 20%.

Costs are driven by the accessibility of the timber and the severity of the decay. Dry rot is significantly more expensive than wet rot because it can travel through masonry, requiring wall sterilisation.

How Long Does It Take?

• Initial Survey: 1–2 hours.
• Standard Woodworm Spray (Single Room): 3–5 hours.
• Whole House Woodworm Treatment: 1–2 days.
• Extensive Dry Rot Remediation: 3–7 days (depending on structural damage).

DIY or Professional?

While surface-level wood stains are a DIY task, structural timber treatment should be left to professionals. Incorrectly identifying Dry Rot as Wet Rot can lead to catastrophic structural failure, as Dry Rot requires specific chemical "barriers" in the surrounding walls.

Professional treatments usually come with a 20 to 30-year guarantee, which is essential for mortgage approvals and future home sales.

Choosing the Right Tradesperson

• Look for PCA (Property Care Association) membership; this is the gold standard in the UK.
• Ensure the surveyor holds a CSRT (Certified Surveyor in Remedial Treatments) qualification.
• Red Flag: Avoid contractors who offer a "free survey" but don't use a moisture meter or provide a written report.
• Question to Ask: "Is your guarantee insurance-backed (IBG) so it remains valid if your company stops trading?"
• Question to Ask: "What is the re-entry time for the property after the chemicals have been sprayed?"

UK Regulations

• Building Regulations (Part A): Applicable if you are replacing structural timbers like floor joists or roof purlins.
• COSHH: Contractors must manage the Control of Substances Hazardous to Health regarding the chemicals used.
• HSE Guidelines: Professionals must follow strict rules regarding ventilation and PPE during application.

Common Problems

• Treating Symptoms, Not Causes: Applying chemicals to rot without fixing the leaking gutter or damp-proof course will result in the rot returning.
• Inadequate Prep: Spraying over dust or old paint prevents the preservative from soaking into the wood grain.
• Missing Hidden Rot: Failing to check wall plates or timber ends embedded in damp masonry.
• Safety Hazards: Not allowing sufficient drying time before pets or children re-enter the treated area.

Frequently Asked Questions