Concrete Chimney Cap - Improves Draft and Prevents Smoke Backflow
48,60 €
48,60 €
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Concrete Chimney Cap - Improves Draft and Prevents Smoke Backflow
Concrete chimney cap: the cap that protects the flue and the façade
A chimney finished with a bare open top has two guaranteed problems. The first is wind: hitting the open mouth from the side, it pushes smoke down and back into the house. The second is water: rain gets into the flue, carries soot down with it, and comes back out at the top leaving black streaks down the brickwork. This concrete cap solves both by covering the mouth and separating the flue from the rain without choking the smoke outlet, thanks to perimeter drip edges that cut off the water before it reaches the pillar.
✅ Key advantages
- Protects the flue from wind: the top slab overhangs the pillar and deflects horizontal gusts, so wind passes over the top instead of getting into the mouth. That's what prevents smoke backflow on stormy days.
- Drip edges on both pieces: the grooved edge breaks surface tension and makes water drop off into the air instead of running down the vertical face. Without a drip edge, water runs down the pillar and stains it; with one, the top stays clean.
- Air flow on all four sides: the legs leave an open chamber around the whole perimeter, so air circulates freely over the flue mouth and helps the draft instead of restricting it.
- Concrete with no internal reinforcement: there's no steel for the acidic smoke condensates to corrode. Nothing to paint, tighten or replace: it needs no maintenance.
- Three formats for three flue sections: 45 × 45, 60 × 60 and 62.5 × 42.5 cm, so the cap covers the opening with margin, neither too small nor overhanging too much.
- Two neutral finishes: Natural Grey and Cement Grey, which age well outdoors and suit both tiled and flat roofs.
🏗️ Recommended applications
- Capping wood-burning fireplaces, stoves and boilers in single-family homes.
- Topping ventilation and extraction ducts on roofs.
- Renovating brick-built chimneys suffering smoke backflow or soot staining.
- New builds wanting a finished cap without resorting to sheet metal.
- Country houses, farmhouses and homes in windy or rainy areas.
📋 Technical specifications
- Material: concrete, no internal reinforcement.
- 45 × 45 × 23.5 cm size: 35.2 kg per unit; pallet of 20 units, 719 kg.
- 60 × 60 × 23.5 cm size: 62.4 kg per unit.
- 62.5 × 42.5 × 23.5 cm size: 43 kg per unit.
- Internal flue section of the 45 × 45 cm model: 22.6 × 22.6 cm.
- Distance between drip edges on the 45 × 45 cm model: 39.5 cm.
- Colors available: Natural Grey and Cement Grey.
- Use: outdoor, on the roof.
- Packaging: single unit or pallet.
🧰 Installation
- Measure the internal flue section and choose the cap whose base fully covers it with firm support all around.
- Level the top of the flue with mortar until you have a flat, horizontal surface.
- Bed the base piece on fresh cement mortar, centered over the opening, and check the level in both directions.
- Place the top slab on the legs, checking that all four air passages remain clear.
- Seal only the support joints. Never fill the gap between the base and the slab: that's where it vents.
- Let it cure for 24-48 hours before lighting the fireplace.
📦 Available formats
- 45 × 45 × 23.5 cm in Natural Grey, single unit or pallet.
- 60 × 60 × 23.5 cm in Cement Grey, single unit or pallet.
- 62.5 × 42.5 × 23.5 cm in Natural Grey, single unit or pallet.
💡 Professional tip: the most common mistake is choosing the cap by the outer size of the pillar instead of the flue section, ending up with a piece that sits unsupported over the opening or doesn't cover it fully. Always measure from the inside. And don't shim the legs to lower the top slab to make it "less conspicuous": reducing the chamber height reduces the outlet section, and the smoke starts struggling to get out. As a good-practice reference in Spain, the chimney mouth should sit at least 1 m above any obstacle within a 2 m radius; if it doesn't reach that, build up the pillar before capping it, because no cap can make up for a chimney that's too short.
Frequently Asked Questions
¿Cómo elijo el tamaño?
Por la sección interior del tiro, no por la medida exterior del pilar. La base del sombrero debe cubrir el hueco por completo y apoyar en firme por todo el perímetro.
¿Por qué evita el retorno de humos?
Porque la losa superior sobresale y desvía las rachas de viento horizontales, que son las que empujan el humo hacia abajo por el conducto. Sin remate, cada golpe de viento devuelve humo al interior.
¿Para qué sirven los goterones?
La ranura del canto rompe la tensión superficial del agua y la obliga a caer al vacío en vez de recorrer la cara vertical del pilar. Es lo que evita los regueros negros de hollín en la fábrica.
¿Se puede sellar el hueco entre la base y la losa?
No. Ese hueco es la cámara de ventilación; si se rellena, se cierra la salida de humos y la chimenea deja de tirar.
¿Se oxida o pide mantenimiento?
No. El hormigón no lleva armadura de acero en su interior, de modo que los condensados ácidos y el agua no tienen hierro que atacar. Basta una limpieza ocasional.
¿Sirve también para conductos de ventilación?
Sí. Cualquier conducto que salga a cubierta y necesite protección frente a la lluvia y el viento admite este remate.
¿A qué altura debe quedar la boca?
Como buena práctica habitual en España, al menos 1 m por encima del punto más alto situado en un radio de 2 m. Por debajo de esa cota aparecen turbulencias y retorno de humos.