Timber
Timber preservation and decay investigation
Assessment and treatment of structural timbers affected by moisture, decay or insect attack.
One condition underlies nearly all of it
Timber problems are moisture problems first
Sound, dry timber in a ventilated building lasts for centuries. Decay fungi and, to a large extent, wood-boring insects need moisture, so almost every timber defect we investigate begins with water arriving somewhere it should not.
Which is why an inspection that identifies "wet rot" and stops there has done half a job. The question that matters is what is wetting the timber:
Roof, gutter, valley and flashing defects wetting roof timbers
Chimney and parapet defects tracking water into embedded timbers
Plumbing and heating leaks, including within floors
Bathroom and shower leaks reaching floor structures
Penetrating damp at wall plates, bearings and joist ends
Blocked, bridged or absent subfloor airflow
Ground moisture and standing water in subfloor voids
External ground levels above internal floor level
Timber built into damp masonry with no isolation
Condensation in cold roof spaces and unheated voids
Our inspections therefore cover the timber and the water: moisture content readings in the affected members, the condition of the surrounding fabric, subfloor conditions where accessible, and the defect responsible.
What the issue is
Timber decay and insect attack are moisture-driven. Effective preservation therefore begins with controlling moisture, followed by proportionate treatment or repair of affected timbers.
Common symptoms
- Soft, crumbling or darkened timber
- Fungal growth or strands on timber
- Exit holes and frass
- Springy floors
- Musty smell
Likely contributing factors
- Persistent leaks or penetrating damp
- Poor subfloor ventilation
- Timber built into damp masonry
- Blocked rainwater goods
Conditions that may be mistaken for it
- Old, inactive insect damage
- Surface staining without decay
- Mechanical damage
How the issue should be investigated
- Inspect accessible timbers and voids
- Test suspect timber condition
- Record moisture content where appropriate
- Establish the moisture source
Potential treatment or repair options
- Removing the moisture source
- Cutting out and replacing decayed timber
- Localised preservative treatment where justified
- Improved ventilation to voids
When treatment may not be appropriate
- Where insect damage is historic and inactive
- Where drying alone will halt further decay
Factors affecting the cost
- Extent of timber replacement
- Access and floor lifting
- Structural support requirements
- Waste disposal
What to expect during an inspection
An inspection of accessible timbers, voids and roof spaces with photographs of findings.
How we inspect
A timber inspection that establishes cause and extent
- 1
Inspect the accessible timber
Roof timbers, floor structures, joist ends and bearings, skirtings, linings, staircases and joinery, looking for decay, deflection, insect damage and the pattern of damage.
- 2
Measure moisture in the timber
Moisture content readings taken in the affected members and in sound timber nearby for comparison, so a wet member can be told from a normal one.
- 3
Identify the mechanism
The water source traced, whether that is a roof defect, a leak, a penetrating defect, a bridged airflow path or condensation.
- 4
Establish extent, and its limits
How far the affected area extends as far as can be seen, and a clear statement of what could not be inspected without opening up.
Where structural timber is involved and the extent cannot be seen, we recommend exposure before repairs are priced rather than guessing at the quantity. - 5
Recommend proportionate work
Stop the water, dry the structure, repair or replace what has lost strength, and treat only where treatment is genuinely justified.
Related work
Timber investigations in detail
Dry rot investigations
Serpula lacrymans identified, its extent established and the moisture source it depends on removed.
Wet rot investigation and repairs
Moisture-driven decay in joinery and structural timber, repaired once the water has been stopped.
Woodworm investigations
Active infestation told apart from historic damage, so timber is only treated where treatment is justified.
Damp surveys and moisture investigations
What a professional damp investigation covers, what the instruments can and cannot establish, and what your written report contains.
Penetrating damp investigations
Rainwater and external defects traced to the elevation, opening or rainwater fitting responsible.
How defective gutters affect walls
How a defective gutter puts water into a wall, and the timber inside it.
Where we work
Timber preservation across Bedfordshire, Northamptonshire and Cambridgeshire
Timber preservation is carried out across our operating area. Choose your county or town to see the work we do locally, the postcode districts we cover and how to arrange an inspection.
Frequently asked questions
Next step
Not sure which inspection you need? Start with a few questions.
Tell us what you are seeing and we will set out what is likely, what is uncertain and which inspection would answer the question. Speak to us on 0333 335 6152 if you would rather talk it through.