Pellet silo in a new build: buried, built-in or external?

How much space does a pellet boiler room need at sketch stage?

Short answer: allow 6 to 16 m² at ground floor or basement level, plus a delivery route of up to 30 m. Lock these dimensions before the building permit — changing them later wastes habitable floor area.

An automatic pellet boiler (EN 303-5 Class 5) needs 2–4 m². A 4–6 tonne silo — a full season without manual refilling — needs 4–12 m² depending on shape. The buffer tank (500–1,000 L) fits in the same zone.

• Boiler: 2.40 m ceiling height, 80 cm clearance in front of the door
• 4–6 t silo: 4–12 m² floor area
• Buffer tank: 1–1.5 m diameter, within 1.5 m of the boiler
• Reserve 30 m from truck parking to the fill point

Three silo options compared in 30 seconds

Silo choice affects living space, build cost and delivery frequency. Compare the three options before the permit application, not on site.

• Buried: saves 6–8 m² of living space, adds €3,000–5,000 in shell works, 1–2 deliveries/year — ideal in new builds with a garage
• Built into plant room: simplest to install, loses 4–8 m² of living space, delivery every 3–4 months
• External (container): zero ground-floor loss, insulated and ventilated, flexible delivery — but visible on the site plan
• Quick rule: ≤ 4 dwellings → buried or built-in; ≥ 8 dwellings → centralised silo with one delivery point

Buffer tank and Klimabonus: two design choices that boost the grant

Klimabonus 2026 funds pellet boilers only. With replacement of a fossil system: up to €8,000 for a single-family home, €4,000 without replacement. In apartment buildings: €6,000 per dwelling, capped at €40,000.

A buffer tank triggers a +15% bonus on the main grant. Solar thermal adds a €1,000 flat-rate top-up. Municipal grants vary by commune and are stackable — check the official simulator.

• Fix the buffer tank at sketch stage: 50–75 L/kW, in the same zone as the boiler
• Solar thermal: collectors on south-facing roof, pipe run ≤ 10 m to the buffer
• Show silo + buffer + solar on the drawings — the grant application requires these locations

Pellet delivery: what the site plan must show

Bulk delivery uses a blower truck (30 m hose). Without vehicle access, the owner refills with bags — more expensive and more work.

Fix the fill point at sketch stage: for a buried silo, through the garage door or a dedicated opening (Ø 10 cm). ENplus A1 pellets are the reference for both the boiler and storage.

• Vehicle access: 2.50 m wide, 3.50 m minimum headroom
• Distance from parking to fill point: 30 m maximum
• Door or opening to the fill point marked on the plan
• 1 delivery per season (4–6 t) with a properly sized silo — not every month