Woodworm treatment for oak beams

How do you treat old wooden beams?

Woodworm experts will usually have to do a full survey of the property.

While woodworm doesn’t necessarily migrate from one beam to another, discovering the extent of a problem is the first stage of dealing with it.

Simply finding holes in beams doesn’t confirm the presence of woodworm now; the damage may be historic and the beetles might have moved on.

The fact that you noticed a hole doesn’t mean it was made the same day.

Usually, the presence of ‘frass’ – the dust produced by mature beetles burrowing out of the wood – is a more reliable indicator there are beetles currently active.

The experts will determine the size of an infestation, the type of beetle involved and usually the stage of a life cycle it is at.

From the results of their investigations, they’ll identify the level of repair that’s needed and choose a treatment accordingly.

There will be different options depending on the level of repair that’s necessary.

Often, while they’re investigating the scourge of woodworm, the experts will also give you a heads-up on any other potential issues of infestation like dry rot and damp.

What do you treat oak beams with?

Once an expert has a handle on the size, extent and type of your woodworm problem, they can begin to treat your beams.

How they treat them, and with what, will depend on the type of infestation you have which is another solid reason why gathering information in advance is crucial.

There are water-based Boron woodworm sprays, which are harmless to people and pets, but which kill the beetles themselves on contact.

They can be effective if beetles are out in the open, which they will be once they’ve emerged because they fly towards sources of light in search of a mate.

Most of the beetles’ life cycle is spent inside the wood.

With that in mind, a treatment for cases of Death Watch beetle will likely be derived from Permethrin (a synthetic chemical that acts like natural extracts from the chrysanthemum), which has to be injected deep into the beams to be sure it kills beetle larvae.

The same treatment can be used on the House Longhorn beetle, with the added proviso that every beam in the house has to be checked ahead of time for infestation rather than just those where there have been visible signs.


How do you treat woodworm in joists?

Where woodworm has been discovered to be active in beams or joists supporting floors or roofs, there is an extra danger to structural integrity.

To some extent, the treatments are the same, with additional precautions recommended by some professionals.

Beetle migration from beam to beam is not by any means guaranteed.

However when they’ve been discovered in joists, some experts recommend removing the infested timber and occasionally beams or joists close nearby in order to remove a known hazard physically and also as a precaution.

As mentioned, migration in woodworm is not by any means guaranteed; once they’ve found an environment that works for them, beetles tend to stay in it for the whole of a life cycle.

But on the basis that it’s better to be safe than sorry, some professionals will advocate the removal strategy, especially when the timber in question is part of a floor or roof that must remain structurally sound.

How fast does woodworm spread?

People are often concerned about the ‘spread’ of woodworm.

It is perhaps an inaccurate way to imagine it because, as we’ve mentioned, most of the lifespan of the beetles we call ‘woodworm’ are spent within the piece of wood where they were born.

Woodworm only tend to ‘spread’ during their maturation period to other pieces of similar and adjoining wood, so this only becomes an issue:

• If you have several beams that are in contact with one another, and have a similar moisture content
• If the beams themselves are already riddled with tunnels, forcing the beetles to eat their way into new territory.

The beetles have a life cycle of between two and five years, so the ‘spread’ of immature woodworm is unlikely to be a major concern.
If a high number of larvae has been deposited in the same beam over time, then you’ll have examples at various stages in a life cycle which may give the impression of a problem that’s spreading.

When beetles emerge, producing those recognisable exit holes, they are looking to mate.

After that, they’ll need a new home in which to deposit their eggs.

That’s a genuine concern in terms of the spread of a problem from beam to beam.

While the frequency of beetle emergence will depend on the numbers reaching maturity at any given time, they generally do so during spring in the northern hemisphere.

With that in mind, be aware of any exit holes, frass or flying beetles between May and August.


How long does woodworm treatment last?

Lots of people ask how long a woodworm treatment lasts.
The honest answer is that it depends on how effectively the treatment is applied.
If you kill all the beetles and larvae in a single beam, then it should endure until, or unless, a beetle from another beam lays eggs there.
If a treatment is less thorough, then it’s likely to be less effective, meaning the problem will not be eradicated and is likely to return when surviving larvae reach maturity and make their way to the surface.
This, of course, is another argument in favour of hiring a professional woodworm specialist to treat your beams; they have more effective chemical treatments in their arsenal, most of them unavailable to a DIY woodworm-killer.

How do you know if woodworm has gone?

Once you’ve had your woodworm treated, ideally by professionals, you’ll want to know that the beetles have gone.
There are several methods you can use.

Fill exit holes with beeswax, or tissue, and see if any new mature woodworm emerges from them.

It’s also useful to take a digital photograph, on your phone, showing the holes.

That will give you a visual reference so you can check any you think are new over time.

Also, keep an eye out for any new frass underneath beams, and any change in the shape or roughness of them because it will indicate the continuation, or resurgence, of a woodworm problem.

What time of year is woodworm active?

People want to know when woodworm are ‘active’.

Again, to wonder as much shows a misunderstanding of the beetles’ life cycle; they’re pretty much active constantly, from the moment larvae hatch until they pupate between two and five years later.

However, they’re active inside a beam during those years rather than making a nuisance of themselves outside.
Mature beetles though emerge in spring – a moveable feast to some extent in some areas beginning as early as March, in others not until around May.

Once the beetles emerge, they have a short window in which to find a mate and lay their eggs before the cycle starts again – usually between 10 and 14 days for a female and around three or four days for a male.

During the mating season, there are things you can do to stop the next generation of woodworm from being spawned; ultraviolet bug zappers are surprisingly effective because the mature woodworm associate light sources with areas they’ll be likely to find a mate.

Is woodworm treatment covered by home insurance?

Woodworm, along with other potential infestations like dry rot, wood-rotting fungi, rising damp or wall tie corrosion, are generally not covered by home insurance.

With that in mind, if you own, or are thinking of buying, a property with oak beams (or indeed any large amount of wood used for structural integrity), it’s worth keeping these exceptions in mind.

That said, some woodworm professionals offer tailored premiums for these infestations to avoid being left in the lurch by your insurer.

If your property’s standard home insurance doesn’t cover woodworm infestation, and if you have a significant number of oak beams, it’s worth calling your local expert and asking if they can cover you.
Insurance can take the financial sting, not to mention the surprise and uncertainty, out of getting a woodworm expert in to deal with a problem.

Woodworm is a complex phenomenon, and it’s always worth calling experts to assess your property if you suspect you have an infestation.

The tenacity of woodworm, and their mostly sub-strata life cycle, make them tough to deal with without professional expertise and chemical solutions.



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