Action sheet — Before the fire
Fitting mesh screens to the air vents: €20 to keep sparks out
Attics, crawl spaces, roof vents: every ventilation opening provides a direct route for wind-borne embers to reach the roof structure. A fine-mesh metal screen, which takes just an hour to fit, seals off this route — it offers the best value for money in terms of protection throughout the whole house.
Key points
- All air inlets: loft, crawl space, roof vents, dormer windows.
- Stainless steel or galvanised wire mesh, with a maximum mesh size of 3 mm — never use plastic fly screens.
- Screw-fixed installation + sealed perimeter: a spark will find its way through even the smallest gap.
- Ventilation must remain effective: use mesh, do not block it.
Equipment: metal mesh with a mesh size of ≤ 3 mm · shears · screwdriver + screws/washers · frames or battens (optional) · stepladder
Why it’s important
The brandons travel far ahead of the fire front and seek out fuel sheltered from the wind: the inside of your loft, lined with dust, insulation wool and dry wood, is an ideal tinder. An unprotected ventilation gap measuring 10 × 20 cm is sufficient. This is the documented cause of many houses that have ‘mysteriously’ burnt from the inside even though the fire had passed some distance away. Fine mesh allows the house to breathe whilst stopping incandescent particles.
How to do it, step by step
Check all the air inlets
Complete survey: loft grilles (gables), roof vents, crawl space vents, disused flues, openwork roller shutter boxes. Note the dimensions.
Choose the right wire mesh
Stainless steel or galvanised steel, 2–3 mm mesh: fine enough to stop embers, yet open enough to allow ventilation. PVC and fibre mesh melt immediately.
Cut out, leaving a 3 cm margin
The hem allows for attachment around the edges. Gloves — the edges cut into the skin.
Secure it properly
Screws and washers every 10 cm on a wooden backing, or a frame made of battens fixed to the masonry. The aim is to ensure there are no gaps wider than 3 mm all the way round.
Check every spring
Corrosion, warping, and flaking: a 5-minute annual check. Clean the grilles if they are blocked to ensure proper ventilation.
The mistakes that ruin everything
- Completely blocking the ventilation ‘just to be on the safe side’: condensation, mould and rotten timbers are guaranteed.
- Use a plastic mosquito net — it melts at the first spark.
- Don’t forget the roof hatches and crawl space access points, which are less visible than the gables.
- Leave a gap around the edge: the embers will squeeze through a 5 mm gap.
The tip that makes all the difference
Whilst you’re at it, fit a spark guard (rolled wire mesh) at the top of the flue: same principle, same embers — in both directions.
Frequently Asked Questions
The risk changes every day. So do your reflexes.
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