Do I need Building Regulations approval to remove a chimney breast?

Yes, chimney breast removal is notifiable building work under the Building Regulations 2010. You need Building Control approval because the chimney breast may be supporting the structure above (stack, upper floor chimney breasts, or the roof). A structural engineer's calculations are typically required to specify the steel beam (RSJ) needed to support the remaining structure.

How much does it cost to remove a chimney breast?

A ground floor chimney breast removal typically costs £1,500-£3,000 including the RSJ, propping, demolition, waste disposal, and making good. Removing on multiple floors costs £2,500-£5,000+. The RSJ and padstones are usually £300-£600 of that total. Prices vary significantly by region and access difficulty.

What size RSJ do I need for chimney breast removal?

The RSJ size depends on the span and the load being carried. For a typical domestic chimney breast (1-1.5m wide), a 152x89 or 178x102 UB is common. For wider spans up to 3m, a 203x133 UB may be needed. The exact size must be specified by a structural engineer based on specific loads — this calculator provides indicative guidance only.

Can I remove a chimney breast on one floor but leave it above?

Yes, this is the most common scenario — removing the ground floor breast while leaving the first floor breast and stack. This requires a gallows bracket or RSJ system to support the remaining structure above. The upper chimney breast and stack become supported by the steel and the party/external wall.

How much waste does chimney removal produce?

A single-storey chimney breast (1.2m wide × 0.35m deep × 2.4m height) produces approximately 1 m³ of brick rubble weighing around 1.9 tonnes. A full chimney removal including the stack can produce 2-4 tonnes. One 8-yard builder skip (4-tonne capacity) is usually sufficient for a single-floor breast removal.

TradeCalculator

Chimney Removal Calculator

Calculate chimney breast volume, brick count, RSJ support requirements, propping needs, and waste tonnage for chimney removal projects in the UK.

Removal Type

What parts of the chimney are being removed

Floors with Chimney Breast

Number of floors where breast is being removed

Breast Width

Width of the chimney breast projection

Breast Depth

Depth of chimney breast from wall face

Breast Height

Floor-to-ceiling height per storey

Stack Height (above roof)

Height of chimney stack above roof line

How We Calculate This

This calculator estimates the volume of brickwork, waste tonnage, and structural support requirements for chimney breast and stack removal. It uses standard brick density (1.9 t/m³ for brickwork including mortar) and common UK chimney dimensions.

Calculation method

Breast volume: Width × depth × height × number of floors. A typical Victorian chimney breast is 1.2m wide × 0.35m deep (one brick + plaster).

Stack volume: Width × depth × height above roof. Stacks are typically narrower than breasts (600mm × 450mm for a single flue).

RSJ sizing: Indicative steel beam sizes are based on standard domestic loading. The actual specification must come from a structural engineer per BS EN 1993.

Waste weight: Total volume × 1.9 t/m³ (dense brickwork). Waste is heavy — an 8-yard skip holds only 4 tonnes of masonry before hitting its weight limit.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.