Rendering Bungaroosh Walls: Techniques and Common Pitfalls
Rendering bungaroosh walls requires more care than applying a standard render system to modern blockwork.
Bungaroosh is an irregular form of mixed masonry found throughout Brighton and Hove. It can contain flint, brick fragments, rubble and other materials bound within lime-based mortar, and the condition can vary considerably across the same elevation.
For that reason, successful rendering starts with the wall beneath the finish.
Before choosing a render system, the construction should be identified, existing defects investigated and any unstable masonry repaired.
Safe-Bricks specialises in bungaroosh, lime render and traditional solid-wall construction across Brighton and Hove.
Why Bungaroosh Is Different to Modern Masonry
Modern blockwork provides a relatively consistent substrate.
Bungaroosh often does not.
Once the existing render is removed, the surface may reveal:
- Flint
- Soft brick
- Broken brick fragments
- Lime-rich areas
- Voids
- Irregular joints
- Previous cement repairs
- Loose masonry
- Areas of historic patching
The background can therefore vary substantially in hardness, suction and stability.
A render specification that ignores those differences is more likely to fail.
Inspect the Existing Render Before Removing It
Existing render should not automatically be stripped from a bungaroosh wall.
Before removal, establish:
- Whether it is cracked
- Whether it has lost its bond
- Whether large areas sound hollow
- Whether water is penetrating through defects
- What type of render is present
- Whether it is causing or contributing to deterioration
- Whether the underlying wall requires structural repair
Where the existing finish remains sound and appropriate, local repair may be preferable to complete removal.
Wholesale stripping creates cost and risks damaging the original wall.
The Main Risk When Removing Hard Render
A common problem is that the existing render is significantly stronger than the masonry beneath it.
This is particularly relevant where a dense cement-rich render has been applied to soft brick, lime-bound bungaroosh or deteriorated mixed masonry.
If large sheets of render are aggressively levered away, the force can remove part of the original wall with them.
Potential damage includes:
- Pulling out flints
- Breaking soft bricks
- Removing original lime material
- Enlarging existing voids
- Damaging wall edges
- Destabilising weak sections
Controlled removal is therefore often necessary.
The objective is not to remove the old render as quickly as possible. It is to remove defective material while retaining as much sound original wall as reasonably practical.
Do Not Use the Bungaroosh as a Levering Surface
One particularly damaging removal method is to drive a tool behind hard render and lever directly against soft original masonry.
Where the substrate is weak, this can crush or pull away the wall itself.
A safer approach can involve working progressively, reducing the size of the render sections and avoiding unnecessary leverage against vulnerable areas.
The exact method depends on how strongly the existing finish is bonded.
Assess the Wall Once Exposed
Removing the render is only the beginning of the repair.
The exposed wall should then be assessed for:
- Loose material
- Voids
- Deteriorated mortar
- Cracking
- Failed previous repairs
- Unstable flints or bricks
- Water damage
- Defective areas around openings
- Structural weakness
A new render should not be used to conceal a defective background.
Repair Bungaroosh Before Rendering
Where the masonry is loose or damaged, it should be repaired before the render coats are applied.
Depending on condition, this may involve:
- Removing friable material
- Re-bedding loose flints
- Re-bedding bricks
- Filling voids
- Rebuilding localised areas
- Repairing wall edges
- Repointing
- Lime mortar repairs
- Structural repair where necessary
The aim is to create a stable background rather than expecting the render to hold the wall together.
Identifying Moisture Sources
Render failure can sometimes be caused by defects elsewhere on the building.
Potential sources of moisture include:
- Leaking gutters
- Failed downpipes
- Roof defects
- Cracked parapets
- Failed flashings
- Poor sill detailing
- Plumbing leaks
- High external ground levels
- Open joints
- Defective window surrounds
If water continues to enter the wall, replacing the render alone may only postpone further failure.
The source should be investigated and repaired first.
Moisture-Meter Readings Are Not Enough
Elevated moisture-meter readings do not automatically prove that the render system is the cause of damp.
They also do not establish whether the moisture is coming from:
- Rainwater penetration
- Plumbing
- Condensation
- Ground-related moisture
- Salts
- Another defect
The building and the pattern of deterioration need to be assessed as a whole.
Where the assessment shows that moisture is being retained within the wall rather than merely passing across its surface, the remedy lies in lime-based damp remediation: repairing the defect supplying the water, allowing the wall a proper drying period, and reinstating in permeable materials before any decorative finish is considered.
Lime Render on Bungaroosh
Lime render is often appropriate for bungaroosh because it can be more compatible with the softer lime-bound masonry beneath it than very rigid cement-rich systems.
Benefits can include:
- Better compatibility with softer substrates
- Greater tolerance of small movements
- Improved drying potential
- Easier future repair
- Reduced risk of concentrating stress into weaker masonry
However, lime render is not a universal answer to every wall problem.
Its success still depends on:
- Substrate preparation
- Repair quality
- Exposure
- Correct mix selection
- Application
- Curing
- Detailing
- Final decoration
Not All Lime Render Is the Same
The term “lime render” covers different products and specifications.
Depending on the project, the system may use:
- Air lime
- Natural hydraulic lime
- Proprietary lime systems
- Different aggregate grades
- Different coat compositions
The appropriate material depends on the wall, weather exposure and required performance.
A highly exposed elevation may require a different specification from a sheltered internal courtyard.
The strongest available lime is not automatically the best choice.
Render Strength Should Relate to the Wall
A basic principle of traditional masonry repair is that the render should not be excessively strong relative to the substrate.
If the render is substantially harder and more rigid than the wall beneath it, stresses can be transferred into the weaker material.
The aim is to provide a protective finish that works with the masonry rather than dominating it.
Typical Multi-Coat Lime Render
A bungaroosh lime-render system will commonly be built up in more than one coat.
A project may involve:
- 1Preparing and repairing the masonry
- 2Controlling suction
- 3Applying an initial coat
- 4Building the required depth with further coat or coats
- 5Straightening and consolidating the surface
- 6Applying a finishing coat
- 7Allowing appropriate curing and drying
- 8Completing with a compatible decorative finish
The exact number and thickness of coats should be determined by the selected system and substrate.
One standard specification should not be assumed to suit every elevation.
Controlling Suction
Bungaroosh can contain areas with very different absorption rates.
For example, soft brick and porous lime-rich material may absorb water rapidly, while flint can absorb very little.
This variation can affect how the render behaves during application and curing.
Substrate preparation may therefore include controlled dampening or other preparation appropriate to the selected render system.
The aim is to prevent the render from losing moisture too quickly into highly absorbent backgrounds.
Flint Creates a Difficult Background
Flint presents a particular challenge because it is hard, smooth and relatively non-absorbent compared with surrounding lime mortar.
Where large flints are exposed, the render needs appropriate mechanical and material preparation to achieve a reliable bond.
The surrounding wall condition is just as important as the flint itself.
Voids and Irregular Surfaces
Bungaroosh is often highly uneven once exposed.
Deep voids should not simply be hidden behind an unnecessarily thick surface coat.
Depending on their size and location, they may require:
- Filling
- Pinning with suitable masonry
- Local rebuilding
- Lime mortar consolidation
This allows the subsequent render coats to be applied over a more stable background.
Reinforcement and Mesh
Reinforcement may be appropriate in selected areas, but it should not be treated as a substitute for repairing defective masonry.
Potential locations can include:
- Junctions between different materials
- Areas around openings
- Localised repaired sections
- Vulnerable transitions
The reinforcement system should be compatible with the render being used.
Applying mesh over unstable bungaroosh and then rendering over it does not repair the wall itself.
Render Beads
Beads may be required at:
- External corners
- Stop ends
- Openings
- Changes in finish
The bead material should be suitable for the render system and exposure.
In lime-render work, the selected bead should not create unnecessary corrosion or compatibility problems within the finished system.
Traditional detailing may also justify forming some edges without conventional modern beads, depending on the building and specification.
Windows and Door Openings
Render failures frequently develop around openings.
Particular attention should be given to:
- Reveals
- Sills
- Lintels
- Corners
- Perimeter seals
- Drips
- Junctions between frames and masonry
These areas can experience both movement and concentrated rainwater exposure.
Poor detailing can undermine an otherwise well-applied render system.
Do Not Render Over Structural Cracks
A new render coat should not be used to conceal unexplained structural cracking.
Where cracking appears significant or continues through the masonry, the cause should be established first.
Potential causes include:
- Movement around openings
- Foundation movement
- Structural alterations
- Failed bearings
- Differential movement between materials
Structural problems may require engineering input before rendering proceeds.
Cement Render on Bungaroosh
Cement render is not automatically defective simply because it contains cement.
Some existing cementitious finishes remain stable for many years.
The relevant questions are:
- Is it well bonded?
- Is it cracking?
- Is it significantly harder than the substrate?
- Is water entering behind it?
- Is the wall deteriorating beneath it?
- Does it need removal to complete the required repairs?
Where a dense and rigid system is contributing to deterioration, replacement with a more compatible render may be justified.
Where it remains sound and the wall is performing satisfactorily, unnecessary removal can do more harm than good.
Common Bungaroosh Rendering Mistake: Treating It Like Blockwork
A contractor familiar only with modern masonry may attempt to:
- Strip the wall rapidly
- Apply a standard bonding product
- Mesh the entire surface
- Apply a hard proprietary render
- Finish as quickly as possible
That approach can overlook the actual condition and variability of the bungaroosh.
Traditional walls often require more preparation before the finishing system begins.
Common Mistake: Rendering Over Loose Material
Render applied to a weak background can detach even if the render itself is perfectly mixed.
The substrate needs to be capable of supporting the system.
Loose masonry should be repaired first.
Common Mistake: Ignoring Active Water Entry
If a leaking gutter continues to saturate the wall, replacing the render will not solve the problem.
Building defects should be addressed in the correct sequence.
Common Mistake: Using an Excessively Hard Mix
A render that is substantially harder than the traditional substrate can increase the risk of cracking and damage to the underlying masonry.
Material strength should be appropriate to the wall.
Common Mistake: Poor Curing
Lime render requires suitable curing conditions.
Rapid drying can impair performance.
Factors such as:
- Hot sun
- Strong wind
- Cold weather
- Frost
- Heavy rain
These conditions can all affect the render during application and early curing.
The work should be protected as necessary.
Common Mistake: Painting Too Soon
The final decorative coating should not be applied before the new render has reached an appropriate condition.
The drying period depends on:
- Coat thickness
- Weather
- Exposure
- Render type
- Substrate moisture
Applying a dense decorative coating prematurely can also reduce the drying potential of the system.
Compatible Decoration
Where a vapour-permeable lime system has been specified to support drying, the decorative finish should normally be selected with that objective in mind.
Potential finishes can include appropriate mineral or lime-based coatings depending on the system.
The final paint should not undermine the performance intended by the render specification.
Coastal Exposure in Brighton and Hove
Brighton and Hove buildings can be exposed to significant wind-driven rain and coastal weather.
A render system therefore needs to balance:
- Weather protection
- Moisture movement
- Durability
- Substrate compatibility
- Maintenance
“Breathability” alone is not a sufficient specification.
An external wall still needs to resist weather effectively.
Listed Buildings and Conservation Areas
Many bungaroosh buildings sit within Brighton and Hove's historic areas.
External render changes can affect:
- Texture
- Detailing
- Colour
- Historic fabric
- Architectural appearance
Listed Building Consent or other planning considerations may apply in relevant cases.
The required permissions should be established before significant changes are made to protected elevations.
A Better Sequence for Rendering Bungaroosh
A considered bungaroosh rendering project normally follows this order:
- 1Identify the construction.
- 2Inspect the existing render.
- 3Investigate active moisture defects.
- 4Repair the causes of water entry.
- 5Remove defective render carefully where justified.
- 6Assess the newly exposed bungaroosh.
- 7Repair loose or unstable masonry.
- 8Prepare the substrate.
- 9Apply the specified lime render system.
- 10Protect and cure the render appropriately.
- 11Allow sufficient drying.
- 12Apply a compatible final finish.
Skipping the masonry-repair stages can leave a visually new render system attached to an unresolved wall defect.
Rendering Bungaroosh Walls in Brighton and Hove
Safe-Bricks undertakes bungaroosh wall repair and lime rendering throughout Brighton and Hove.
Our work can include:
- Controlled render removal
- Bungaroosh repair
- Local rebuilding
- Lime mortar work
- Substrate preparation
- Multi-coat lime rendering
- Window and reveal repairs
- Internal lime plastering
- Compatible decoration
Need Advice on a Bungaroosh Render Repair?
If your render is cracked, hollow, detached or exposing bungaroosh beneath it, send Safe-Bricks photographs for an initial review.
Useful photographs include:
- The complete elevation
- Close-ups of cracks
- Hollow or detached areas
- Any exposed bungaroosh
- Windows and sills
- Gutters and downpipes
- The base of the wall
- Internal areas showing corresponding staining or damage
From these photographs, we can often establish whether the problem appears to be limited to the render or whether the underlying bungaroosh also requires investigation.
Not sure where to start?
Send us photographs of the area of concern. It is the most straightforward first step — we will look at what you can see and advise on the appropriate next steps.