diy treatment woodworm
While browsing the internet I came across an old article featured in the Telegraph on line
http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/5038527/DIY-advice-Woodworm – Written by Jeff Howell
It was in answer to a question about how to treat woodworm in an old British house. While reading the article it occurred to me that the advice was particular to a British house and not our local Portuguese conditions.
In fact when gathering building advice its always best to adapt the advice to local conditions. For instance The timber used in Portuguese construction differs a lot from that of the UK. Take a house of 80 years old for instance.
The main structural beams holding up the roof, first floor will be chestnut or oak. If they are perfectly round the old beams may have been replaced at some time with eucalyptus.
The timbers acting as lintels across doors and windows will be olive or oak.
Floor joists will be pine, oak, cherry or eucalyptus.
Roof joists will be pine, oak, eucalyptus or whatever grows locally in abundance.
Internal finishings of pine or hardwood from Brazil are common. The hardwoods tend to last but the pine and oak get devoured by woodworm and this includes wooden flooring blocks.
In the UK for instance the vast majority of timber used in house building is pine so that when a home is infested with wood worm it can quickly spread to structural elements.
An old house in Portugal will never be dry enough to deter woodworm from taking up residence. The timber used in construction is not very often kiln dried so that it can have the eggs or larvae still inside it when its used to build your house.
Because there is a lot of what is called hardwood used in Portuguese building we also have more types of wood boring insects than you would normally find in a uk property as some types of wood worm prefer hardwood to soft wood.
The article –
“A With any kind of wood-boring insect damage, the first thing to ascertain is whether the infestation is still active. Woodworm holes are the “flight holes” made by adult beetles when – following several years as larvae, burrowing beneath the surface – they pupate, hatch out, and make their way into the open air. So flight holes themselves are a sign that the insects have departed, not evidence of continued infestation. You have stated that your house has active woodworm, so I assume you have verified this either by finding live larvae below the surface, or from evidence of bore dust coming out of the old flight holes. However, before using pesticides, I suggest you make absolutely sure the infestation is still active, by vacuum-cleaning the affected areas of timber, and spreading newspapers underneath to catch any telltale signs of fresh bore dust production.
Following that, the most important thing is an accurate identification of the insects. I recommend the book Recognising Wood Rot and Insect Damage in Buildings by Bravery et al, from (01344 328038). Common furniture beetle, the most common form of “woodworm”, might be nibbling the sapwood at the edges of some softwood timbers, but is rarer in hardwoods such as oak.
In fact there should be no reason to treat lintels, as in an old house upgraded to modern standards of heating and ventilation they should soon become too dry to support insect life, as should floorboards and joists. Roof timbers can be harder to dry out, but, even so, insect damage is often only in the sapwood on the surface or corners of the timbers, and poses no structural threat.
Surface treatment using any kind of chemical will never penetrate right through the timber, regardless of how often you do it, so you have to expect flight holes to continue to appear for five years or so, until the last-born larvae have evolved to adulthood. Ultraviolet insect killers (“insect-o-cutors”) can help by catching the adult beetles during the March to August flying season before they can mate and lay fresh eggs. Boron-based wood preservative (not “borax”) is one of the safer pesticides for amateur use, as it is water-based and can be applied by brush rather than spraying. But the conundrum with any kind of surface chemical treatment is that if the treated timber remains damp, you might still get infestation and, if it is dried out, then you won’t need chemical treatments anyway.”
If you are worried about insect damage to your house in Portugal contact