Woodworm Treatment & Timber Preservation in Cardiff & the Vale of Glamorgan

What Is Woodworm?

‘Woodworm’ is not a single species — it’s a collective term for the larval stage of several wood-boring beetle species that feed on and tunnel through timber. The damage you see (the exit holes, the fine powdery dust known as frass) is caused by the larvae as they feed through the wood over a period of years, and by the adult beetles as they bore their way out to mate and lay eggs on new timber surfaces.

The lifecycle of a wood-boring beetle follows four stages: egg, larva, pupa, and adult. The larvae spend the vast majority of their lives — typically between two and five years, depending on species and conditions — feeding inside the timber. The exit holes that most people associate with woodworm only appear when the adult beetle emerges, usually between May and September. This means that by the time you spot the holes, the infestation may have been active for several years already.

Species of Wood-Boring Beetle Found in UK Properties

Several different beetle species are responsible for woodworm damage in Welsh and UK properties. Identifying the species correctly matters, because different beetles attack different timber types and require different treatment approaches.

Common Furniture Beetle 

By far the most frequently encountered wood-boring beetle in UK homes. The common furniture beetle attacks both softwood and hardwood, preferring the sapwood portions of timber — the outer layers just beneath the bark. It’s responsible for the majority of woodworm infestations found in roof timbers, floorboards, joists, staircases, and old furniture. Exit holes are small and round, approximately 1–2mm in diameter, and fresh frass has a gritty, lemon-pip texture. Adult beetles are small, brown, and oval-shaped, typically 2.5–5mm in length.

House Longhorn Beetle 

The house longhorn beetle is significantly more destructive than the common furniture beetle, capable of completely hollowing out structural softwood timbers while leaving the surface apparently intact. Fortunately, in the UK it is largely restricted to certain areas of Surrey and southern England, it is rarely encountered in Wales. However, it’s worth being aware of, particularly in properties with timber sourced from Europe where it is more prevalent. Exit holes are oval rather than round, and considerably larger — 6–10mm across.

Deathwatch Beetle 

The deathwatch beetle is a serious pest of old hardwood timbers, oak, elm, and chestnut in particular and is most commonly found in ancient buildings, churches, and period properties with original structural hardwood. It’s associated with timber that has already been partially softened by fungal decay, making damp conditions a significant risk factor. Exit holes are larger than those of the common furniture beetle, approximately 3mm in diameter, and the frass has a disc-like or bun-shaped texture. Cardiff and the Vale have a number of older and listed properties where deathwatch beetle can be a genuine concern.

Bark Borer Beetle 

The bark borer attacks timber that still retains its bark — most commonly found in rough-sawn roof timbers where bark has been left on the wood during processing. Infestation is usually limited to the bark and immediately adjacent sapwood, and the structural timber beneath is typically unaffected. Treatment may not be required if the bark is removed.

Signs of an Active Woodworm Infestation

The presence of exit holes alone doesn’t confirm an active infestation — old holes from a long-dead population are very common, particularly in older properties. Our surveyors look for specific indicators of current activity:

• Fresh frass: Fine, pale bore dust that hasn’t yet discoloured. Fresh frass falls freely from holes and may be visible on surfaces below infested timber. Old, settled frass is darker and more compacted.
• New exit holes: Holes with clean, pale, sharp edges indicate recent emergence. Older holes have darker, rounded, worn edges.
• Adult beetles: Finding dead or live adult beetles near or beneath infested timber between May and September is a strong indicator of active infestation.
• Tunnelling audible in quiet conditions: In severe infestations, the sound of larvae feeding can sometimes be heard — this is actually the origin of the name ‘deathwatch’ beetle.
• Structural weakness: Timber that crumbles, gives way under light pressure, or feels unusually light may have been extensively tunnelled. This is most critical in load-bearing timbers.

Where Woodworm Commonly Occurs in Cardiff Properties

Woodworm can attack any accessible untreated timber, but certain areas and property types are particularly vulnerable. In Cardiff and the Vale of Glamorgan, we regularly encounter infestations in:

• Roof timbers and loft spaces: Rafters, purlins, ridge boards, and ceiling joists in older properties are among the most commonly infested structural timbers. Poor ventilation and fluctuating humidity in loft spaces create ideal conditions for wood-boring beetles.
• Floorboards and floor joists: Particularly in Victorian and Edwardian terraces where original softwood boards and joists have never been treated. Subfloor dampness increases the risk significantly.
• Staircases and stair treads: Original timber staircases in period properties — particularly the undersides of treads and the string timbers — are frequently affected.
• Structural joinery and built-in furniture: Old fitted cupboards, panelling, window seats, and similar joinery elements are common hosts, particularly where they contain older, un-treated softwood or sapwood.
• Antique furniture: Older furniture brought into a property can introduce woodworm. A piece with an active infestation can spread to structural timber if not treated.
• Structural hardwoods in listed and period properties: Deathwatch beetle in original oak or elm timbers is a particular risk in older properties across Llandaff, Pontcanna, Penarth, Cowbridge, and the Vale.

Woodworm Treatment — Our Approach

Not every property with woodworm exit holes requires treatment — but identifying whether treatment is needed, and applying the right product to the right timber, requires experience and qualification. Our approach follows PCA best practice guidelines throughout:

• Survey and species identification: We inspect all accessible timber, identify the species responsible, determine whether the infestation is active or historic, and assess the structural condition of affected timbers.
• Moisture assessment: Wood-boring beetles thrive in damp conditions. We check timber moisture content and identify any underlying damp issues — because treating woodworm without addressing elevated moisture levels is only half the job.
• Insecticidal treatment: Where treatment is required, we apply a high-quality insecticidal preservative — typically a permethrin-based or boron-based solution — by low-pressure spray to all affected and at-risk timbers. The product penetrates the timber surface and creates a toxic barrier against emerging adults and newly hatched larvae.
• Structural assessment and reinstatement: Where timbers have been significantly weakened by woodworm damage, we assess whether strengthening or replacement is required and carry out any necessary remedial work.
• Guarantee: All woodworm treatment work carried out using Sovereign Chemicals or Wykamol approved products is backed by a treatment guarantee.

Woodworm & Property Transactions

Woodworm is one of the most frequently flagged issues in RICS homebuyer survey reports and mortgage valuations across Cardiff and the Vale. If you’re buying a property and a timber survey has flagged a suspected woodworm infestation, or if you’re selling and want to resolve an issue before it becomes a sticking point, we can carry out an independent specialist survey and issue a report and treatment guarantee that satisfies solicitors, mortgage lenders, and prospective buyers.

Many woodworm issues flagged in general property surveys are historic rather than active and a specialist survey from a PCA qualified expert can often resolve the concern quickly and cost-effectively, without the need for extensive treatment.