Small Holes in the Rafters: A Letter to an Owner Who Has Just Been Up the Loft Ladder

Dear owner,

You went up to look for a leak, or to fetch the Christmas boxes, and shone a torch along a rafter. There were small round holes in it, and perhaps a little pale dust on the beam below. Your stomach dropped. Let me answer the question you are really asking: no, you do not need to ring anyone tonight, and you should not buy a tin of anything yet. Looking, writing down what you see and watching for a while is the right first move.

What you have probably found

Holes in old roof timbers are not unusual. Babergh District Council puts it plainly: "Finding signs of wood-boring insects (or 'woodworm') - particularly in older buildings - is not uncommon." It names the main UK species as furniture beetles and death watch beetles, and says a damp building is the usual underlying cause.

I would not try to name the beetle from a torch beam. What matters first is a simpler question: is it still going on, or did it finish long ago?

Live or finished?

The same council gives two clues. First: "An active outbreak can sometimes be identified by holes with sharp (rather than rounded) edges, alongside bore dust." Holes with rounded edges and no fresh dust beside them point the other way, though I would still check them again before relying on that.

Second, and this is the sentence I would pin to the loft hatch: "If you are not sure whether you have an active presence of beetles, you should monitor the situation for a year."

Looking, writing down what you see and watching for a while is the right first move.

A year is a long time to be patient with something that frightens you. It is also what makes the later decisions sound, because a year shows you whether fresh dust appears in the autumn and spring.

How I would watch for a year

Nothing here touches the building:

1. Photograph the timbers you are worried about, with a coin or a ruler beside the holes, and date the pictures.
2. Lay a sheet of clean paper or card on the floor beneath, or on the beam, and leave it there. Fresh dust will show up against it.
3. Look again each month and on the first dry day after rain. Note the date, and what had changed.
4. Do not poke, probe or scrape the timber to test it. Old oak is easier to damage than to heal.
5. Check for the cause as well as the effect: a stained ceiling below, a gap in the slates, a wet patch on a wall plate, a gutter that overflows onto the wall. I wrote about how trapped water behaves in damp in an old house.

The damp is the real patient

If I could take only one thing from the council's page into your loft, it would be the damp. If a damp building is the usual underlying cause, then mending the gutter, the slate or the flashing that has been letting water in is, in my judgement, among the most useful things an owner can do, and it touches little historic fabric.

So when you have written your notes, go back through them and ask: where might water be getting in? That is a question you can start answering from the garden with binoculars.

If it turns out to be active

The council says: "If you have an active infestation, you might need to apply treatment straightaway." So watching is not a rule for all cases, and if you can see fresh dust piling up week on week, I would not wait out the year. Get the timber looked at, by someone who knows old roofs.

On what to use, Babergh states its preferences, and I would read them as one council's view, not a universal rule: "A paste treatment is the preferred option, as it will penetrate the holes better than sprayed chemicals". It adds: "We typically do not support spray treatment, as it is harder to control." And it warns that drilling to get a spray closer to the insects "can be very damaging to historic fabric".

My own judgement, labelled as such: I would be wary of any quotation that begins with the words "the whole roof". A beetle attack is often patchy, and good treatment usually follows the evidence from the timbers, not a blanket.

Where consent comes in

Section 7 of the 1990 Act says that no person shall execute works "for the demolition of a listed building or for its alteration or extension in any manner which would affect its character as a building of special architectural or historic interest, unless the works are authorised under section 8."

Whether a given treatment crosses that line is a question for your own council. Babergh's answer for its area is that "For a comprehensive spray treatment, you will need listed building consent", and that it would "expect to see an independent assessment of the buildings, which justifies its necessity". A small, local paste treatment is a different thing from a whole-roof spray, and your council may see it differently. Cutting out and replacing a decayed timber is different again, because it changes the fabric itself.

GOV.UK's planning practice guidance says that where there is any doubt, owners are encouraged to "discuss the matter with the local planning authority". I would make that call before anyone lifts a brush, and I would have the photographs and notes from your year to hand when I do. Councils tend to be more helpful to an owner who arrives with evidence than to one who arrives with a worry.

When a professional earns their place

There are three moments when I would want help:

• When the dust keeps coming, or when the timber near the holes feels soft, crumbly or visibly smaller than it should be.
• When a timber carries something important, such as a roof truss, a tie beam or a wall plate, where a decision to treat, repair or replace is partly a structural one.
• When the cause is not obvious, and the water getting in has to be traced through a roof, a gutter and a wall.

A heritage architect can read the roof as a whole, work out what is likely to need consent, and help you to ask a timber specialist and a structural engineer the right questions. It is the same patient looking I described in what I look for on a first visit, applied to one corner of the house. If you are planning to insulate the roof space as well, please read my piece on the three ways to insulate a listed roof (the related guide above) first, because insulation that hides timbers makes watching them much harder.

A note on the rafters

Old roofs have carried more weather than most of us will ever see, and small holes are often only the mark of something that finished long ago. I would sooner a house were watched with a torch and a notebook than hurried into a treatment it did not need.

Speak to Giles if you would like a second opinion on what you saw in the loft: book a conversation, get in touch, call +44 (0)7737 745211, or send a WhatsApp voice note.

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Giles Paul Shorter — ARB registered · RIBA Chartered Member · on the RIBA Conservation Register · 17+ years specialising in listed and historic buildings.