“Is the woodworm infestation in my house active?” – I am asked this question all the time.

Exit holes in wall timbers

Usually this comes as the result of an observation made by a RICS surveyor during the initial Homebuyer survey where signs of woodworm attack might have been noted. Most likely, he/she will have noticed small holes in the floor boards or roof timbers. These are exit holes where the adult beetle has emerged.

Commonly, the guidance in the report will be for you to contact a PCA registered contractor in order to gain further specialist advice. This is where I would take issue with the wording of the RICS surveyor’s report.

The usual recommendation in a Homebuyer report

Why would you ask a contractor (someone who has a vested interest in finding work) to carry out an inspection on the timbers of a house where woodworm is suspected? Whilst many contractors I am sure are honest, more often than not they will recommend a chemical insecticide spray treatment of the timbers (and sometimes even the whole property) as a “precautionary measure”. This is usually because they are unsure as to whether the insect attack is active or not. A happy coincidence of this uncertainty is billable work!

After spending anything in the region of £600 – £1,500 you are rewarded with a bit of paper that guarantees the invading insects have been exterminated and will not return for 20 – 30 years. Sound familiar?

Exit holes in floorboards

Let’s rewind a bit and see what should have happened. You receive an instruction from your RICS surveyor to have the timbers inspected further. Or perhaps you have noticed some holes in the floor or roof timbers of your house and you are concerned with the possibility of woodworm infestation.

If your are living in an old house (let’s assume “old” means that it pre-dates 1920) the chances are that the signs of insect attack are historic and therefore not active. But how can we be sure of this before having the flooring pulled up and nasty chemicals sprayed all over your house?

Firstly, your legal advisor should investigate and determine whether or not guarantees exist relating to any timber treatment that may have taken place. If so they should be checked to see if they are still in date. Most timber treatment guarantees are good for 20-30 years and subsequent re-infestation is not a common occurrence in treated timbers during this period. So if the paper work checks out then we can reasonably assume that the evidence noted by the surveyor is sign of historic woodworm attack. There is therefore, no need for so called “precautionary treatment”.

Frass indicates active woodworm

But can we be doubly sure that there is no insect attack present? The answer is YES. A proven method that is rarely mentioned onsite is what I call “The Paper Test”. This involves covering in lining paper the timbers that we suspect be infested. The area is then monitored over a number of years. If holes appear in the lining paper along with deposits of “frass” (powdery wood chewings deposited by the beetles) then active infestation can be confirmed.

80% of the woodworm attack found in the UK is as the result of Common Furniture Beetle. Even when infestation is active, in the majority of cases this is not something to be overly concerned about. Rarely is the attack severe enough that it causes serious damage to the structural integrity of a property.

A suitably trained and qualified surveyor should be able to confirm for you as to whether the woodworm that you have is active or historic.