Wood worm advice required

22 May 2016
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United Kingdom
Hi everyone,

After recently purchasing our property, I've found some patches woodworm holes in the main roof joists. They are mainly at the upper half of two joists and from what I can tell they don't seem to be active.

I've attached the photos below and would appreciate any advice given.


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I don't see dust so perhaps they are old holes. I can't see the scale in your pics. Poke the wood with a flat-blade screwdriver (don't use anything round or pointy as the holes will look like worm) to see if there is any weakening of the timber. If not, clean it well and apply several flowing coats of wood preserver or woodworm fluid on the affected area and on other timber. Warm and humid areas, e.g. around loft hatch and over bathrooms, and bathroom floors, are most prone to attack. You will have to lift the loft insulation, and I would hoover up the dust as well. Modern centrally heated houses tend to be too dry inside for worm.

I prefer a fluid with colour in it so you can see the treated areas. Some fluids can be sprayed with an airless sprayer but use a protective mas, gloves and protection for your skin and eyes.

I have always been happy with Cuprinol products https://www.cuprinol.co.uk/products/woodworm_killer.jsp but there are others which might be cheaper. 5-star also protects against rot https://www.cuprinol.co.uk/products/5_star_complete_wood_treatment_(wb).jsp

If you prefer, get a preservation company in and you should get a (worthless) guarantee against recurrence.
Thanks very much JohnD for your advice. I've used a screwdriver with a flat-blade and twisted it a few times. Although on the face of it the wood has come off, it seems to be okay underneath. But I'll leave you to judge that.....

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I can't see the tunnelled, crumbly texture of weakened worm-eaten wood. You can break it apart in your fingers, and a screwdriver will punch into it.

Yours looks sound to me.
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Excellent, thanks John. I forgot to mention that there is absolutely no heating in the loft and with the roof not being insulated, the loft can get very cold indeed. Not sure if the woodworm would be able to survive such cold.

Now do I need to cover the whole loft or just the affected areas?

Also does cuprinol cover a large area or would I be better off purchasing one of these? :-


My friend has got a spray pump, so can cuprinol be used with that?
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I would be cautious of spraying. If no instructions shown, contact their helpdesk. The treatments are intentionally poisonous.

The instructions show the number of sq.m per litre to get correct coverage.

You have got to treat all the affected areas, but I would presume that the beetles are flying all round the loft to lay eggs, so I would prefer to treat all surfaces.

I don't know the ingredients and coverage of that other product. IIRC Cuprinol for Woodworm used to contain Permethrin but chemicals may be revised.
I'm sure I read somewhere that Cuprinol definately contains Permethrin too.

To be perfectly honest, if I had to cover a large area of the loft, then I'd rather spray it than brush it. Of course, I'd take all the required precautions, such as ventilations, masks. I'll also cover small sections of the attic, taking breaks to allow any airborne particles to settle and then continuing again

I've seen this WOODWORM KILLER & this WOODWORM KILLER on ebay. One of the sellers has 100% feedback and they both are only £16.25 each, but 1L would dilute to 25L. I guess if you think it's worth a shot, I could get a couple of these gallons, make a more stronger mixture, i.e. 1L to 20L and spray it in the whole of the attic.

What do you think? Am I doing this wrong?
I don't think you need to make it stronger. But additional coats, wet on wet, soak in deeper and improve protection.
I suggest that if you remove one or more of the drawing pins that are, for some reason, stuck in that timber, you will find that the holes they have made are identical to all the other holes. In fact on some of the holes you can see a slight chamfer where the pin has been pushed in. And some of the holes are not round.

That is, not woodworm.

LOL! I was thinking the same too and yes, maybe some of the holes have possibly been created by pins. However, these pin holes are also showing on some of the floor joists too, so I have two choices. Either I can treat the whole place of leave it and hope for the best. Now is there away I can check for definite that there are no woodworms?
you might be able to purchase the correct water bourne fluid from the likes of 'safeguard chemicals'?
that way you know you have obtain the proper stuff,from ebay you might just be buying water??

normally if you have found it in 1 area of the attic then you probably have in other areas.
have you used a hammer to bang the rafters to see if any frass comes out?
if it does it might be a good idea to lay some white paper directly underneath the suspected area to see if any fresh frass appears.

iirc this is the time for the adults to sort migrating out of the timber,depending on type of worm.

make sure you use the correct ppe,and a decent fume mask,also before spraying make sure you sweep the whole of the roofing timbers down
then lift any insulation,then you can spray to your hearts content.
also advisable to turn off electrics apart from the cooker socket,
but we used to use a pump and hose/lance setup,you may well be using a garden sprayer?

bear in mind what above has been said though.it MAY be old flight holes,but for peace of mind only you can answer that.
Thanks gregers for your helpful advice. I know you said that the ebay stuff could be water, but it's from a reputable company that has a 100% of over 27000 feedbacks from customers, so I guess I'll take my chances and have ordered a 5Ltr gallon to cover the whole loft. I've also ordered FFP3 respirator masks, so that I don't breath in the fumes. I plan to remove all the old insulation, then sweep the whole roof timbers down. Only once this is complete, will I start spraying. FYI, my friend has this sprayer, which I'll be borrowing:-


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