Collapsing Grade II Bay Window Repairs

Grade II Listed Building Bay Window Saved From Collapse

AWT was contacted by very concerned homeowners of part of a Grade II listed c 1800 farmhouse with several structural engineers’ reports stating the bay window was unstable and that rebuilding was the only recourse, but that was contrary to Historic England’s preferred solution and their wishes.

The double bay window was supported with props to prevent collapse. In common with many properties that AWT repairs, this property showed signs of previous ineffective structural repair work.

AWT was able to realign and reinforce the structure without the need for pattress plates, tie bars or other visible reinforcement. AWT’s specialist structural repair techniques also allowed the owners to avoid slow, expensive and inconvenient deconstruction and rebuilding of the ground floor bay to install new lintels. AWT’s specialist repair techniques were classed as a repair by Historic England which greatly simplified the entire process.

Read our frequently asked questions about bay window structural repairs.

The Structural Problem

When AWT was called in to repair this Grade II listed property the bay window masonry had been supported for 2 years with props to prevent collapse.

The homeowners structural engineer report had warned that the structure “could be close to the tipping point” and recommended that the ground floor bay be rebuilt and the first floor repaired. Deconstructing the ground floor masonry and rebuilding it with additional lintels would have been slow and costly, not to mention disruptive to the residents. AWT’s specialist structural repair techniques allowed the owners to avoid slow, very expensive and inconvenient deconstruction and rebuilding of the ground floor bay to install new lintels.

The owners were delighted that AWT could offer a much better solution to the property’s bay window’s many structural defects.

The structural problems included:

  • Brick arches over the ground floor windows slipped by 20-25mm
  • Brick arch nearest the left-hand brick pier pushed out by approx. 20mm
  • Fractured brickwork & mortar joints opened up
  • Pronounced, 60mm bulge in left-hand brick pier
  • 25mm bulge in right-hand brick pier
  • Cracks in brick columns
  • 650mm long crack in 1st floor internal wall
  • External brickwork movable & wall ties completely fractured
  • Ongoing movement with cracks and bulges increasing month on month
  • Collapse of outer brickwork only a matter of time

The Structural Repair Solution

AWT’s specialist repair techniques were classed as a repair by Historic England which greatly simplified the entire process.

AWT, adopting their uniquely developed realigning equipment, was able to lift and realign the original structure’s fabric, therefore, conserving the original features and textures. Despite the advanced nature of the bay window defect, only the outer layer of the brick columns required deconstruction and rebuilding with new handmade shaped brickwork (the original bricks were too decayed to be used.)

As can be seen in the gallery below, the doors and windows remained in situ throughout the work, keeping the disruption to the homeowners to a minimum.

AWT works realigned and reinforced the bay window, reinstated stability and maintained the appearance without the need for pattress plates, tie bars or other visible reinforcement.

Hydraulic realigning equipment, designed by AWT,  was used to lift and realign the arches and brickwork before reinforcing the masonry. Using AWT’s specialist drilling equipment, stainless steel fixings are installed within the masonry. This strengthens the structure and redistributes the load from the upper-story masonry. The hidden fixings and remedial wall ties also restrain the brickwork from bulging.

The reinforcement work included:

  • Bed Joint Reinforcement – Beaming
  • Fenestration lintel- brickwork arch repair
  • Precision Diamond drilling
  • Lateral restraints
  • Grout tie injection
  • Location and isolation of corroded wall ties
  • Remedial, resin-bonded wall ties
  • Deconstruction & rebuilding of just the outer skin of the bay pillars
  • Brickwork repairs and repointing.

Action Wall Ties are specialist structural repair contractors with the skills and experience required to repair Grade I, Grade II and Grade II* listed heritage buildings.  AWT work along with property owners, structural engineers, architects, project managers and local authorities on large and small projects.

AWT are available in Kent, London, Essex, Surrey and Sussex. To arrange a survey or to discuss project details, please use our contact form, email us or call us on 01227 721 255.

Remedial Wall Ties for Victorian Semi in Surrey

Bulging & Cracking Brickwork Across Front of Victorian Semi Detached Houses

These 2 Victorian semi detached houses in Egham, Surrey had a significant bulge in the brickwork above the first floor windows. There was also a failing brick arch lintel and cracking to the brickwork. Without swift action the masonry would collapse.

AWT were called in to repair the defects and allow the homeowners to avoid slow, expensive and disruptive rebuilding work. Equipment designed by AWT was used to realign the brickwork, stabilise and reinforce the masonry and then install new wall ties and lateral restraints.

Surrey bowing masonry repairs - Remedial Wall Ties for Victorian Semi in Surrey

The Structural Problem

The AWT survey team visited the property in Surrey, TW20 to identify the root cause of the visible bulging of the masonry at the front of the property. The AWT survey team quickly identified that this Victorian semi was built using cavity wall construction and that failing cavity wall ties were likely a root cause of the problem.

A limited inspection of the wall ties was undertaken by drilling 12mm holes in the outer leaf of brickwork to view within the cavity via an endoscope. This confirmed the diagnosis of failing wall ties, as can be seen from the photos taken with the endoscope, as the corrosion of the metal was clearly visible. The mild steel ties were all in a similarly heavily corroded condition and showing signs of de-laminating.

Failing Victorian wall ties surrey - Remedial Wall Ties for Victorian Semi in Surrey

Horizontal cracking, lifting and opening up of joints was noted at irregular intervals on the front elevation. Metal ties were located behind the cracks, with an electronic wall tie locator.

Corrosion of the embedded mild steel wall ties was causing them to expand to many times their original size. This was damaging the outer leaf of brickwork, splitting the bed joints and causing either lifting or bowing of the walls and damage to internal finishes. This left the wall vulnerable to vertical and wind loads, especially such a large gable wall.

Without structural repairs the wall would continue to bow further and eventually collapse. Traditional building methods would have required the partial deconstruction and rebuilding of the front of the properties.

The Structural Repair Solution

Completed wall tie repairs Surrey - Remedial Wall Ties for Victorian Semi in Surrey

Unlike some cavity wall tie repair contractors, AWT always works to the standards laid out in the Building Research Establishment Specification Digest. This means that the separation between new wall ties, the layout pattern of the new wall ties and the material used to manufacture the new wall ties all meet the highest standards to ensure a safe, long term structural repair.

To avoid failure of the brickwork and brickwork arch AWT realigned the bulged brickwork, installed new stainless steel wall ties, isolated the old ties to prevent them causing further damage and formed a composite beam within the external brickwork. The formation of deep masonry beams within the existing masonry supports the masonry and maintains the integrity of the brickwork.

AWT use their own custom designed hydraulic realignment equipment and diamond bladed precision drilling rigs. This allows the new fixings to be installed with minimal disturbance to the masonry. A variety of specialist fixings were introduced into the brickwork to restore the strength and stability of the wall.

As can be seen in the photo above, when the work is complete there are no visible fixing either inside or outside the property. The AWT team also take the time to colour match any replacement bricks as well as matching the colour, texture and pointing style of the mortar where work has taken place.

AWT provide cost effective structural repairs for a wide range of structural faults including failing cavity wall ties and bulging brickwork. We operate not only in Surrey but across the whole of London and the South East of England.

To book a time for one of our surveyors to visit your property or to discuss your requirements, call us today on 01227 721255, email us at enquiries@actionwallties.co.uk or use our contact form to get in touch.

Concrete Frame Remedial Works

Concrete Frame Remedial Works

Inspection of this 9 storey concrete frame tower block revealed serious defects in the previous remedial works by another company. AWT installed remedial head restraints and wall ties to restore structural integrity.

Oldmead - Concrete Frame Remedial Works

 The Structural Problem

This circa 1970s nine storey social housing apartment block in Dagenham that was over clad some two years previously with a polystyrene insulation system, that was deemed unsafe and removed to be replaced with PermaRock mineral Fibre EWI system. AWT was contracted to undertake an intrusive inspection of the wall ties, head restraints and visible concrete elements.

This concrete framed building’s cavity infill walls rely on wall ties to provide a degree of interaction between the two leaves, increasing vertical load and resistance to lateral movement (generally wind load) than two leaves acting separately and head restraints to tie the inner and outer walls to the concrete frame. Sound, correctly installed wall ties and head restraints are vital to the structural stability.

The British Standards Institution and the Building Research Establishment Specification Digest provide clear guidelines for the fitting of wall ties and head restraints in concrete framed buildings. Not only must the appropriate type and size of wall tie and head restraint be fitted but the number of fixings per square metre and the pattern of fixings within the masonry must also be considered.

Our Structural Repair Inspection

The AWT inspection comprised a limited inspection of the existing wall ties by drilling 12mm holes in the outer leaf of the brickwork to view within the cavity using an Endoscope. A metal detector was used to establish the remedial wall tie density and distribution and condition.

Our inspection revealed the original wire butterfly wall ties were in poor condition and found to be over their useful lifespan. Many of the original wall ties were also incorrectly installed or not embedded at all.

The remedial wall ties installed to replace the original butterfly ties were installed poorly and with insufficient population. Insufficient or incorrectly fitted head restraints dramatically reduce the load bearing capacity of the brickwork. If wall ties are broken, missing or incorrectly fitted this can allow the masonry to bow and crack.

The remedial wall ties were installed in an erratic pattern rather than the recommended pattern for maximum load capacity. The majority of the remedial wall ties had been installed in the mortar bed joints rather than into the bricks. The wrong length of ties had been fitted and insufficiently resin bonded. Many of these wall ties could be removed by hand!

The head restraint fittings were also incorrectly fitted with many being too long and protruding out of the brickwork rather than being securely fixed within the masonry.

oldmead head restraint - Concrete Frame Remedial Works

The Structural Repair Solution

AWT provided high quality remedial work that is designed to last. Our skilled operatives take pride in their work and are committed to ensuring that every project they complete is safe.

High quality remedial ties were carefully installed in the correct pattern and density. Head restraints were also fitted to restore structural integrity.

C1  - Concrete Frame Remedial Works

AWT provide cost effective, safe remedial repairs to concrete framed buildings throughout London and the South East.

To book a time for one of our surveyors to visit your property, call us today on 01227 721255, email us at enquiries@actionwallties.co.uk or use our contact form to get in touch.

Social street housing

Social street housing

An estate of terraced and semi-detached social street housing of cavity construction, with corroded mild steel cavity wall ties – wall tie treatment

case study 56e19a2e79c0d8.46786177 - Social street housing

The subject buildings form an estate of terraced and semi-detached social street housing of cavity construction under pitched roofs.

Problem

The existing wall ties viewed were found to be mild steel vertical twist ties, commonly known as fishtail ties. The galvanised coating was found to be in varying stages of corrosion, blackened with red rusting noted.

case 11 a 1 - Social street housing

The corrosion of the embedded mild steel wall ties had resulted in the formation of ferrous oxide, which had expanded to many times its original thickness lifting and cracking the brickwork.

An archetypical example of a wall with the symptoms of expansive corroding wall ties lifting the bricks cracking the bed joint horizontally that has simply been re-pointed. This action has only temporarily addressed the symptoms and NOT the causation.

case 11 b - Social street housing

Solution

AWT completed a remedial programme providing a comprehensive repair through the introduction of a pattern of remedial wall ties and isolating the existing ties, together with general brickwork repairs and re-pointing.

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems in London Surrey and Kent. Contact us on 01227 721 255, or email us.

1950s style two-storey semi

1950s style two-storey semi

Wall tie treatment and weather struck re-pointing to 1950s style two-storey semi-detached house of the type typical of Kent and London.

case study 56e19a3932fe02.00956868 - 1950s style two-storey semi

The subject property comprised a 1950s style two-storey semi-detached house of cavity wall brick construction.

Structural Problems with these wall ties

The existing wall ties viewed were found to be mild steel vertical twist ties, commonly known as fishtail ties. The wall ties were found to be heavily corroded, fractured and delaminated.

case 12 a - 1950s style two-storey semi

The corrosion of the embedded mild steel wall ties had resulted in the forming of ferrous oxide, which had expanded to many times its original thickness, lifting and cracking the brickwork.

case 12 b - 1950s style two-storey semi

Solution for a wall tie repair and replacement

AWT completed a remedial programme providing a viable repair through the introduction of a pattern of remedial wall ties and isolating the existing ties, together with general brickwork repairs and weather struck re-pointing.

case 12 c 2 - 1950s style two-storey semi

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems in Kent and London. Contact us on 01227 721 255, or email us.

 

1950s semi-detached wall ties

1950s semi-detached wall ties

Wall tie treatment and cavity cleaning to 1950s semi-detached house to provide a structural repair for rusting wall ties and DPC issues.

case study 56e29950c47c11.83163531 - 1950s semi-detached wall ties

The subject building was a conventional 1950s cavity-built semi-detached house.

Problem – corroded de-laminated wall ties

An AWT investigation with a metal detector and an endoscope revealed that the wall ties to the front, right side and rear elevations were galvanised mild steel vertical twist ties, all in a similar heavily corroded condition, showing signs of de-laminating.

Side gable wall:
This had a significant bulge at first floor level from the front to the window. This area required the external skin to be carefully dismantled and rebuilt.

Corroding wall ties were clearly visible. The internal walls at ground floor level were also found to be damp.

Corrosion of the embedded mild steel wall ties had resulted in the forming of ferrous oxide, which had expanded the metal to many times its original thickness, lifting and cracking the brickwork. It was considered likely that the lateral movement noted was due to the absence of effective wall ties.

Bridging of cavities at DPC:
Our investigation revealed that the building had areas within the cavity that were blocked with decayed mortar that bridged the DPC.

Discussion

Wall ties:
AWT’s opinion, based on the Building Research Establishment (BRE)’s recommendations, was that the symptoms/defects noted were consistent on all elevations requiring remedial work. It was considered that the building would benefit from remedial wall tie replacement and the isolation of the existing ties.

case 13 a - 1950s semi-detached wall ties

Bridging of cavities at DPC:
The bridging of the DPC had rendered it ineffective and could result in rising damp.

Solution – remedial wall tie replacement

AWT completed a remedial scheme providing a viable repair by introducing remedial wall ties, isolating the existing ties and cavity cleaning.

Wall tie treatment:
AWT operatives completed remedial wall tie treatments to the front, right side and rear elevations in accordance with AWT’s Wall Tie Treatment – Generic Repair.

Cavity cleaning:
We cleaned the cavities to the ground floor DPC at the front, right side and rear elevations in accordance with our specifications and AWT’s methods. This meant the removal of sufficient external brickwork to enable the removal of discarded mortar debris, leaving the cavity clear to below the DPC while at all times maintaining the integrity of the wall.

Action Wall Ties (AWT) are the South East specialists in wall tie replacement, masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems. Contact us on 01227 721 255, or email us.

 

Bowing gable wall 1950s style two-storey semi

1950s Semi with Bowing Gable Wall

Bowing gable wall to a 1950s style semi-detached house in Sittingbourne, Kent. Remedial wall ties, isolating the existing ties, bed joint reinforcement beaming, crack stitching and lateral restraints.

case study 572c74b2d05cb8.37806035 - Bowing gable wall 1950s style two-storey semi

The subject property in Swale, Kent, comprised a 1950s style two-storey semi-detached house of cavity brickwork construction.

Problem – Gable wall bowing & cracking

The gable wall: The right side gable wall had a visible outward bulge at the centre of the wall at first floor level and significant cracking was noted (no corresponding internal cracking was present). The front elevation external skin was rebuilt after suffering damage in a hurricane. No downward movement at DPC level was noted.

An AWT investigation with a metal detector and an endoscope revealed that the wall ties viewed to the right side gable wall and rear elevations were mild steel vertical twist ties, all in a similar heavily corroded condition and showing signs of de-laminating.

Horizontal cracking, lifting and opening up of joints were noted at irregular intervals on the right side and rear elevations, with corroding ties clearly visible.

Discussion

Right side elevations: We believed that the movement was progressive, due to ineffective and/or inadequate restraining, and not attributable to significant subsidence.

Wall ties: Our opinion, in accordance with the Building Research Establishment’s recommendations, was that the symptoms noted above were likely to be representative of the majority of the cavity wall ties to the right side, and the main rear elevation suffering from corrosion.

It was believed that the building’s right side and main rear elevation would benefit from remedial wall ties and the isolation of the existing ties.

The Ridgeway - Bowing gable wall 1950s style two-storey semi

Structural Repair Solution

AWT completed a remedial scheme providing a viable repair by introducing remedial wall ties, isolating the existing ties, then employing bed joint reinforcement beaming, crack stitching and lateral restraints.

Remedial wall ties and isolation of existing ties: Our operatives undertook remedial wall tie treatment to the right side and main rear elevations in accordance with AWT’s wall tie treatment – Generic Repair.

Bed joint reinforcement beaming: The introduction of two rows of twin 8mm stainless steel corded joint reinforcement forming a deep masonry beam – as indicated with red double dotted lines on our proposal plan.

Crack stitching: We stitched localised cracks with the introduction of single 8mm stainless steel corded joint reinforcement – as indicated by red single dotted lines on our proposal.

Lateral restraints: At approximately 900mm centres we drilled for, and screwed directly into alternate timber floor joist’s end grain or into the side grain, 8mm stainless steel lateral restraints into the timber floor and ceiling joists, all resin bonded to the masonry along with corresponding wall ties – as indicated with green stars on our proposal plan.

Make good the pointing: To the cracking schedule for reinforcement listed above, and to areas of weakness to pointing to the right side elevation, we raked out the existing cracked mortar and repaired with new coloured sand and cement mortar to approximately 20mm in depth. AWT operatives are highly skilled in traditional building methods and always attempt to match replacement bricks, pointing styles and mortar colour to be sympathetic with the existing building.

Homeowners, landlords, housing associations and councils across Kent, London, Surrey and Sussex can call on AWT’s experts to repair rusting wall ties and other structural problems. Action Wall Ties (AWT) are specialists in gable wall repairs, masonry reinforcement and repair. We provide professional solutions to a wide variety of structural problems. Contact us on 01227 721 255, or email us.

13-storey building with bi-metallic wall tie corrosion

13-storey building with bi-metallic wall tie corrosion

Circa 1960/70s 13-storey concrete frame building with bi-metallic corrosion to wall ties – replacement wall ties

case study 56e19acc773b12.45946151 - 13-storey building with bi-metallic wall tie corrosion

The subject building was a circa 1960/70s 13-storey, high-rise block of maisonettes of concrete frame construction with single and two-storey brickwork veneer to the South and North elevations and two-storey inset balconies of fenestrations and cavity infill walls to the East and West elevations.

Structural Problems with walls and brickwork

The cavity infill walls were constructed of good quality multi-red stock bricks externally (all in stretcher bond) with 70-80mm cavity and lightweight blocks internally.

The infill walls were constructed on the inset concrete floor with a bituminous felt DPC cavity tray on the concrete floor. No raked-out perps or weep holes were noted.

The brickwork was found to be generally in good condition, with some signs of cracking and distress noted to the south elevation. The pointing appeared to be of a good standard and had weathered well, with the exception of the brickwork below the windows to the east and west elevations.

Inspection with an Imp wall tie detector and the use of an endoscope to every brickwork panel revealed that the wall ties were vertical twist ties and were located in “Abbey Anchor” dovetail slots cast into the concrete wall.

The vertical twist ties had a fishtail end built into the brickwork and a dovetail end that engaged into the dovetail slots embedded to the concrete wall. The embedded slots appeared to be galvanised and in good condition, with no corrosion noted.

The ties viewed were in poor condition with varying degrees of corrosion noted.
• Loss of section had occurred on the built-in fishtails.
• Laminated corrosion was present on the upper surface.
• No corrosion was noted on the dovetail end.

case 26 a - 13-storey building with bi-metallic wall tie corrosion

Discussion

The aggressive localised corrosion was deemed to have been significantly exacerbated by bi-metallic action, with the slot becoming cathodic (positive) and the tie becoming anodic (negative), creating a “corrosion hot spot” fuelled by moisture and oxygen within the bed joint. It was also noted that the underside of the portion of tie within the cavity had not corroded, but the upper section covered in mortar had.

The severity of the corrosion noted was significant, and if left to continue without repair it would most likely result in the opening up of the bed joints and cracking of the wall panels and cost much more to repair.

Some horizontal cracking, lifting and opening up of joints were noted at irregular intervals.

Metal ties were located behind the cracks with an electronic wall tie locator. Some corroded wall ties requiring repair were clearly visible.

case 26 b - 13-storey building with bi-metallic wall tie corrosion

Wall Tie Replacement and Repair Solution

AWT completed a remedial scheme providing a viable repair through the introduction of a pattern of remedial wall ties and the isolation of the existing ties, followed by re-pointing.

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing cost effective wall tie replacement and repairs and professional solutions to a wide variety of structural problems in Surrey, London and Kent.

Replacing wall ties are a speciality of ours and we have developed cost effective repair techniques, avoiding more costly repairs if left later down the line, so to discuss these with us please contact us on 01227 721 255, or email us.

Failing concrete support toes

Failing concrete support toes

Twelve storey concrete frame building with failing concrete support toes – install stainless steel angles reinforcement and re-tie infill walls

case study 56e19ad841d6c3.98871744 - Failing concrete support toes

The subject of this case study was a 12-storey concrete frame building with brick infill walls believed to have been constructed in the 1960s.

Problem: Cracks and failing concrete toes/wall ties

The building was of a concrete frame and floor construction, with cavity brickwork infill walls. The infill walls were constructed with an external brick skin on a single course high concrete toe that was visible above the fenestration openings and balcony soffit.

a. Cracking movement was noted to the infill walls.

b. Sections of the concrete toes were found to be failing, along with sections of the external brickwork not supported by the concrete toe.

case 27 a - Failing concrete support toes

 

c. A wall tie deficiency was evident.

Solution – Concrete Repair

AWT completed a remedial scheme, providing a viable repair by the introduction of 10mm stainless steel reinforcement to the concrete toe, remedial wall ties and general brick repairs. Establishing our reputation as a quality concrete repair company.

case 27 b - Failing concrete support toes

Making good and pointing: AWT operatives are highly skilled in traditional building methods and always attempt to match replacement bricks, pointing styles and mortar colour to be sympathetic with the existing building.

Action Wall Ties (AWT) are a specialist concrete repair company, working with concrete, and offering masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems. Contact us on 01227 721 255, or email us to discuss your concrete and masonry cracks and issues for a quote and simple quick and reliable solution.

Corroded mild steel cavity wall ties

Corroded mild steel cavity wall ties

An 1950s estate of street housing with corroded mild steel cavity wall ties – remedial wall tie treatment

case study 56e19c2cec4b78.12947654 - Corroded mild steel cavity wall ties

The subject buildings form an estate of terraced and semi-detached social street housing of cavity construction under pitched roofs.

The wall tie problem

The existing wall ties viewed were found to be mild steel vertical twist ties, commonly known as fishtail ties.

The galvanised coating was found to be in varying stages of corrosion, blackened with red rusting noted.

The corrosion of the embedded mild steel wall ties had resulted in the forming of ferrous oxide (rust), which had expanded to several times the thickness of the metal it had resulted from, in turn lifting and cracking the brickwork.

Remedial Wall Tie Solution

AWT completed a remedial programme providing a viable repair through the introduction of a pattern of remedial wall ties and isolating the existing ties, together with general brickwork repairs and re-pointing.

Call us for a quote for our specialists wall tie repairs, our tools and techniques allow us to complete the work quickly with a minimum of disruption and at a very reasonable price.

Action Wall Ties (AWT), covering Kent, London, Surrey and Sussex are specialists wall tie replacement and in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems. Contact us on 01227 721 255, or email us.

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