How to Price Chimney Breast Removal: Structural Support, Debris and Redecoration

Quick Answer: Removing a chimney breast in a UK domestic property typically costs £2,500–£5,500 per chimney breast at one floor level, or £4,500–£9,500 for full removal across two floors plus stack. Costs vary by scope: ground-floor only with retained upstairs ("Gallows brackets" or steel beam); full removal floor-to-roof (steel beam, lateral restraint, roof patching); and chimney stack removal above roof level. Building Regulations Part A (structural) and Party Wall etc. Act 1996 apply on most jobs. Engineer's calculations and Building Control sign-off are mandatory; LABC inspection fee £200–£450.

Summary

Chimney breast removal is one of the most frequently-quoted, most-frequently-underquoted refurb jobs in UK housing. Customers see it as "knock the chimney out" — they don't see the steel beam, the lateral restraint to the gable wall, the Part A structural calc, the Party Wall notice, the lath-and-plaster make good, the floor-board lift to install padstones. The job involves at least four trades (builder, structural engineer, plasterer, occasionally electrician for new fittings) and 1–2 weeks on site for a typical full-removal scope.

The legal framework starts with Building Regulations Part A (structure). Any removal of load-bearing masonry requires structural engineer's calculations, Building Control notification, inspection at the steel-installed and steel-encased stage, and a completion certificate. Without certification, the property's value is reduced (buyers' surveyors will flag it), home insurance may exclude structural defects, and conveyancing can stall.

The Party Wall etc. Act 1996 applies because most chimneys sit on the party wall between semis or terraced houses. Notice (typically Section 6 or Section 2) must be served on the neighbour 2 months before work starts. Customers and builders frequently overlook this — and frequent post-completion disputes follow. Quote always includes a recommendation that the customer engage a Party Wall surveyor; this is the customer's cost (not the builder's), but it's part of a competent quote.

Key Facts

• Chimney breast (one floor only, partial removal) — £2,500–£4,500
• Chimney breast (full one-floor with steel) — £3,500–£5,500
• Full removal (two floors + roof patching) — £4,500–£9,500
• Stack-only removal (above roof level) — £1,800–£3,500
• Steel beam (typical 152×89×16 UB) — £150–£300 supply
• Padstones (concrete bearing pads) — £40–£80 each, 2 needed per beam
• Engineer's structural calc — £350–£650 typical
• Building Control fee (LABC) — £200–£450
• Party Wall surveyor (each side) — £700–£1,400
• Skip (4 yard, debris) — £200–£350; often two skips needed (£400–£700)
• Lath and plaster make-good — £85–£140/m²
• Modern plasterboard make-good — £35–£65/m²
• Floorboard make-good (suspended timber) — £45–£85 per linear m
• Roof tile make-good (after stack removal) — £350–£900 typical
• Lead flashing replacement (chimney removal) — £180–£400
• Lateral restraint straps — £25–£60 per strap; typically 4–6 per job
• Standards — Building Regulations Part A (structure), Part J (combustion appliances retained), Party Wall etc. Act 1996

Quick Reference Table

Detailed Guidance

Three Scopes of Removal

Scope A — partial removal, one floor only: The chimney breast is cut out at one floor (usually ground), with the breast above (and the stack) supported on a "Gallows bracket" or similar metal frame fixed to the party wall above. Acceptable historically but increasingly disfavoured by Building Control because of the lateral loads imposed on the party wall. Many councils now refuse Gallows brackets and require full beam-and-padstone support.

Scope B — full removal, beam and padstone support: The breast at both ground and first floor is removed, with a steel beam at first-floor or ceiling level supporting the masonry above. Padstones at each end of the beam transfer the load into the party wall. This is the modern standard for chimney breast removal where the stack remains.

Scope C — full removal including stack: Stack removed above roof, both floor breasts removed, roof patched in matching tile. Eliminates all chimney structure. Most thorough; most expensive. Removes future maintenance concerns.

Structural Engineering: What's Calculated

The engineer calculates:

1. Dead load — weight of masonry above the cut, including stack
2. Live load — wind on the stack, snow, dynamic loads
3. Beam selection — UB (universal beam) sized to span across the room with appropriate deflection limits
4. Padstone size — concrete bearing block transferring beam load into party wall, sized for masonry crushing strength
5. Lateral restraint — additional ties or straps connecting the now-unsupported masonry above the cut to the floor or roof structure

A typical calc £350–£650; engineer issues a structural report and drawings used by Building Control.

Lateral Restraint: The Detail Frequently Missed

Removing a chimney breast removes a significant tie between the party wall and the rest of the house. Without proper lateral restraint, the gable wall above the cut can move independently in high winds, causing cracking and in extreme cases collapse.

The standard remedy:

• Galvanised steel restraint straps — 6 mm × 30 mm × 1200 mm, fixed to floor or roof joists at one end and to the party wall at the other
• Spacing — typically 2 m maximum
• Fixing to wall — through wall plug or resin anchor, into solid masonry
• Coverage — both at ceiling/floor level above the removed breast and at the roof level

This detail must be on the engineer's drawings and inspected by Building Control before the make-good is closed in.

Party Wall etc. Act 1996

The Act applies because:

• Most chimneys sit on or are part of a party wall
• Removing the chimney affects the party wall structure
• Section 2 of the Act (work on existing party walls) is the relevant clause
• Section 6 (excavations within 6 m of a neighbour's foundation) may also apply

Procedure:

1. Notice served on neighbour 2 months before work starts
2. Neighbour responds in writing — agree, dissent, or do nothing
3. If dissent or no response: a Party Wall Surveyor is appointed (usually one for each side, or one Agreed Surveyor)
4. Award document prepared and signed
5. Works proceed in line with the Award

Not following the Act is not illegal but exposes the homeowner to civil liability; if damage occurs the neighbour can sue and the absence of a Party Wall Award severely weakens the homeowner's defence.

Building Control Sign-Off

Required for any chimney breast removal involving structural change. Process:

1. Application before work starts — submit engineer's drawings and calc, scope of work
2. Inspection 1: After steel beam installed, before encasement
3. Inspection 2: After lateral restraints in place, before plaster
4. Inspection 3: Final completion inspection
5. Completion certificate issued — keep for property file

Time: typically 4–6 weeks from application to first inspection. Quote programme should reflect this.

Stack Removal and Roof Patching

Where the chimney stack is removed above roof level:

1. Scaffold the chimney — chimney scaffold £400–£700
2. Strip tiles around the stack — 1.5–2 m radius
3. Remove the masonry stack — break out with disc cutter and SDS, lower debris carefully
4. Insert new rafters — short rafters to span the void where the stack was
5. New deck and underlay — match existing
6. New tiles — match existing as closely as possible (often a problem with discontinued tiles)
7. New flashings — usually no longer needed (no abutment), but eaves and ridge details must continue

Roof patching is the trickiest visual element. Old tiles weather and discolour over time; new tiles in a 1m × 1m patch stand out. Reusing some original tiles around the patch and putting new tiles in less visible areas is the standard solution.

Floor Make-Good

When a chimney breast is removed at ground floor:

• The hearth space remains in the floor — fill with appropriate sub-base (compacted Type 1)
• New joists span where the breast was
• New floorboards or chipboard match existing
• Skirting board run continuously along the wall

For first-floor removal:

• The void above the original ground-floor breast is now opening between two rooms upstairs
• Floor joists may need extending and noggings installed
• New floorboards over the void

Make-Good and Decoration

The room loses ~1 m × 0.4 m of floor space behind the breast — desirable, since this is why the customer is doing the work. The make-good:

• Brick or block infill of the original opening
• Plasterboard and skim, or render and skim
• Coving to match existing
• Skirting and architrave to match existing
• Wallpaper or paint finish

A whole-room redecoration is often advisable. Discrete patching rarely matches existing decoration, and customers commonly decide on a full repaint anyway.

Live Stove / Open Fire Considerations

If the customer's chimney is currently in use (gas fire, log burner, open fire):

• Cap the flue at top first — bird-proof cap or full mortar cap
• Disconnect any gas appliance and have it Gas Safe certified as removed
• Remove appliance and dispose
• Survey for liner — if a liner exists, retract from top before removal

This affects Building Regulations Part J — combustion appliance removal must be certified and the flue rendered safe.

Frequently Asked Questions

Can the customer just remove the chimney without telling Building Control?

Legally no — chimney breast removal is a structural change to load-bearing masonry. Building Control notification is mandatory. Non-compliance:

• Sale of property may stall when surveyor flags unauthorised structural alteration
• Mortgage lender may require retrospective certification (which the council can refuse if the work is non-compliant)
• Insurance may exclude claims arising from the affected area

Always quote with Building Control sign-off included as a line item.

How long does the whole project take?

A typical full-removal job takes 5–10 working days on site, plus 4–6 weeks lead time for engineer's calc, Building Control application, Party Wall notice. Total elapsed time from quote to completion is often 8–12 weeks.

What if there's a flue from a working appliance below or above?

Flues must be considered carefully. If the ground floor breast is removed but there's a working stove on the first floor, the flue is now disconnected. Either:

• Cap the flue and disconnect the appliance (loses the appliance)
• Re-route the flue (rare, expensive)
• Don't do the removal

This is a key survey point before quoting — never assume.

Can the flue be retained as a "feature"?

Some customers want the chimney shape retained as a "feature" without the breast. This is possible — the breast removed at floor levels, the stack and breast above first-floor preserved, exposed brick or rendered. Costs more than full removal because more careful demolition is needed. Engineer's design typically more complex.

Why is the survey so important before quoting?

The variables are huge: brick or stone, single or twin flue, lined or unlined, working appliance or capped, party wall or solo, Victorian or 1930s, terraced or detached. Every survey reveals a different scope. A quote without a proper survey is a guess. Charge for a survey if needed, and re-quote after the survey.

Regulations & Standards

• Building Regulations Approved Document A — structural safety

• Building Regulations Approved Document J — combustion appliances (retention or removal of flues)

• Building Regulations Approved Document P — electrical (cables in chimney walls)

• Party Wall etc. Act 1996 — full text and notice procedures

• BS 5628 / BS EN 1996-1-1 — masonry design (engineer reference)

• BS 6178 / BS EN 1990 — actions on structures (loading)

• Building (Approved Inspectors etc.) Regulations 2010 — inspector competence

• Approved Document A Building Regs — structural safety

• Party Wall Act Explained — government guidance

• LABC Technical Guidance — Local Authority Building Control practitioner notes

• Institution of Structural Engineers — engineer's calc requirements

• Faculty of Party Wall Surveyors — surveyor selection

• British Constructional Steelwork Association — steel beam selection guidance

• structural removal and temporary shoring — the demolition-side process

• chimney survey before alteration — pre-quote survey method

• lath and plaster repair after removal — heritage make-good

• chimney repairs and removals on roof — roof-side stack work

• Party Wall notice template — customer-facing notice format