Registered Pest Control Operator · Reg. No. P54412 · 30+ years, second-generation technician
Out of every part of a home I inspect for wood borer, the roof is the one that actually really stressed me out… It’s the one place where the damage isn’t just cosmetic.
Let’s talk about it.
Why Roof Timber Takes the Worst of It
A roof void is close to the perfect environment for wood borer. It’s dark, it’s warm, and along our coast it holds humidity far better than most other parts of a house. Add in the fact that almost nobody goes up there between inspections, sometimes for years at a stretch, and you’ve got timber left completely undisturbed for exactly as long as the beetle needs.
The problem is… A truss is what’s actually holding your roof up.
Homes in areas like Berea, Morningside, Glenwood, and parts of Durban North often still have their original timber trusses, sometimes decades old, in roof voids built before modern ventilation standards. Combine that with our humidity and you’ve got roof timber that’s had a long time, and exactly the right conditions, to be quietly worked on by wood borer.
It’s also worth knowing that not every wood borer species is equally interested in your roof. The Common Furniture Beetle, the one most people picture when they hear “wood borer,” mostly goes after furniture and softer, exposed timber like floorboards and skirting. Th
e one I actually worry about up in a roof void is the House Longhorn Beetle. It’s larger, it favours structural softwood specifically, and it’s the species most associated with genuine truss damage.
Warning Signs to Check For (Safely)
You don’t need to climb into your roof void yourself to get a sense of whether something’s wrong. Start with what’s visible from below, or through an existing access hatch.
- Fine dust along ceiling boards or in the roof void. This is frass, and fresh, pale dust means active beetles nearby.
- Small round holes in exposed beams, usually one to two millimetres across, left by adult beetles emerging from the timber.
- A truss that looks like it’s sagging or bowing. Timber doesn’t bend like that on its own (this is an urgent issue).
- A hollow sound when you gently tap exposed timber near the eaves (this means the inside has been eaten away).
How Far Is Too Far
Honestly, this is the part that’s genuinely hard to judge from the ground.
Wood borer damage isn’t uniform. A beam can look fine on the surface while the larvae have hollowed out a meaningful part of its cross-section underneath, or it can carry old, dormant exit holes from an infestation that’s already been treated and poses no ongoing risk. Telling those two apart takes a proper probe test on the timber itself: how much solid wood is left, versus how much has been eaten away.
Once enough of that cross-section is gone, a truss stops carrying load the way it was designed to. That’s the point where the conversation moves from treatment to structural repair.
Not sure if your roof timber is still sound? That’s exactly what a proper inspection is for. See how our Wood Borer Treatment works.
Get in Touch →Treating Early vs Replacing a Roof
I’ve broken down what wood borer treatment itself tends to cost in this article.
This said:
Treating a handful of affected trusses while the damage is still localised is a pest control job. Removing and rebuilding a truss structure once too much of it has been compromised is a construction job.
The gap between those two outcomes usually comes down to how early the problem was caught.
The Bottom Line
A roof truss is the one part of a wood borer infestation I take most personally, because it’s the one part where getting it wrong actually puts people at risk.
None of this means an older home is doomed. It just means the case for a periodic roof void check is stronger here than it would be for a newer build inland; and it’s a lot cheaper to make that call early than late.
If you can safely get eyes on your roof void, a photo of what you’re seeing tells us a lot before we even arrive. If you can’t, or you’re not sure what you’re looking at, try our termite or wood borer checker or give us a call.
Thank you, and God bless.
Mark Abraham
Registered Pest Control Operator · Reg. No. P54412 · Structural Pest Control (Commercial & Domestic), Dept. of Agriculture, Act 36 of 1947
Frequently Asked Questions (FAQs)
Can I check my own roof for wood borer?
You can look for visible signs from a safe vantage point, such as an existing access hatch, but avoid walking across ceiling boards, which aren’t built to take your weight. If you spot dust, exit holes, or sagging timber, that’s the point to call a professional rather than investigate further yourself.
What do I do if I find exit holes in my ceiling?
Book an inspection rather than treat it yourself. Surface holes don’t tell you how much timber underneath has actually been affected, and that’s exactly what a proper inspection is designed to establish.
Will my whole roof need replacing if I have wood borer?
Usually not. Most infestations are caught while still localised to a handful of trusses, which is a treatment job rather than a rebuild. Full replacement is only needed once damage has progressed far enough to compromise a truss’s structural capacity.
How do you tell if roof damage is old or active?
Fresh, pale frass and clean exit holes point to an active infestation. Older, discoloured holes with no fresh dust usually mean past damage that’s already run its course. A probe test on the timber itself confirms how much solid wood remains either way.
Is roof timber more at risk than other wood in my home?
It’s not necessarily more attractive to the beetle, but it is more exposed. Roof voids stay dark, warm, and undisturbed for years at a time, which gives an infestation far longer to develop unnoticed than timber you walk past every day.
Can wood borer actually cause a roof to collapse?
If enough of a truss’s cross-section is eaten away, yes, it loses the load-bearing capacity it was built with. This is genuinely rare, since most infestations are caught before it gets that far, but it’s the reason roof damage gets treated as urgent rather than cosmetic.
You Might Also Like
Wood Borer Treatment Cost in Durban
What actually drives the price of wood borer treatment.
Does Home Insurance Cover Wood Borer Damage?
What your policy probably won’t pay for, and what will actually protect you.
The Risks of Not Treating Wood Borer in Durban
Why it’s the pest I worry about most, and what happens if it’s ignored.