Public Sector Archives - Action Wall Ties

London School with Bowing Brickwork

London School with Superstructure Issues & Bowing Walls

wall bulge repairs 01 300x225 - London School with Bowing Brickwork — After – No Visible Fixings

This primary school in Southwark, London, had significant visible bowing to the second-floor right side flank wall, putting the structure at risk of collapse. Progressive movement was impacting the entire building and required a plan to reinforce and restrain all the brickwork. Previous repairs had failed to halt the movement of the structure.

According to estimates, to repair the defects using traditional building methods the school would need to close for 6 months. AWT completed their work in just over 2 weeks during the school summer holiday. AWT’s work was also significantly cheaper, accounting for less than 25% of the original projected cost.

wall bulge 03 225x300 - London School with Bowing Brickwork — Bowing Wall

wall bulge 10 225x300 - London School with Bowing Brickwork — Wall Bowing Outwards

AWT worked with the Education Service and the consulting structural engineers to design a permanent, cost-effective structural repair that would minimise disruption to the school’s staff and pupils.

The Structural Problem

wall bulge 09 225x300 - London School with Bowing Brickwork — Bulging Brickwork

wall bulge 08 225x300 - London School with Bowing Brickwork — Bowing Wall

wall bulge 07 225x300 - London School with Bowing Brickwork — Bowing Brick Wall

The building was a Victorian/Edwardian period property that had been extended and converted into a school. There was significant visible bowging to the front section of the second-floor right side flank wall. There was also bulging brickwork between the rear third floor windows.

These structural defects were severe – nearing the tipping point. Without urgent action, the structure would collapse. The rest of the property was also suffering from movement within the structure, therefore the entire building required remedial work.

during bowing brick repairs 01 300x225 - London School with Bowing Brickwork — Failing Timber Beams

The building appeared to be solid brickwork, however, AWT was prepared for the possibility of decaying timbers within the structure. When the internal plaster was removed, it revealed failing wooden beams that could not support their load.

The Structural Solution

during bowing brick repairs 03 225x300 - London School with Bowing Brickwork — Bowing Wall Realignment

during bowing brick repairs 04 225x300 - London School with Bowing Brickwork — Realigning Bowed Wall

The structural repairs included:

Brickwork Realignment
Removal of Failing Timber
Internal Restraint Posts for Severely Bowed Areas
Bed Joint Reinforcement Beaming
Lateral Restraints
Resin Bonded Ties
Resin Bonded Stainless Steel Pins
Brickwork Repairs

wall bulge repairs 04 230x120 - London School with Bowing Brickwork — Brickwork Reinforcement

wall bulge repairs 02 230x120 - London School with Bowing Brickwork — Realign & Strengthen

wall bulge repairs 03 230x120 - London School with Bowing Brickwork — Realign & Reinforce

AWT’s specialist tools and techniques allowed them to straighten and reinforce the brickwork without visible fixings. The severely bowed wall was reinforced with internal restraint posts that would be hidden when the plasterwork was reinstated.

AWT introduced stainless steel reinforcements deep within the masonry. The formation of continuous beams within the existing masonry redistributes the upper-storey loads and restrains diagonal cracking and bulging tendencies.

after brickwork realignment 01 225x300 - London School with Bowing Brickwork — After Structural Repairs

after brickwork realignment 02 225x300 - London School with Bowing Brickwork — Repaired Bowing Brickwork

AWT stabilised the superstructure of the building and repaired the bowing brickwork in just over 2 weeks. This allowed plenty of time for the internal finishes to be reinstated before the start of the new school year, thus avoiding any disruption to the pupils.

As well as providing an efficient, long-term solution, AWT’s work was also very cost-effective, accounting for less than 25% of the original projected cost.

Action Wall Ties are specialist structural repair contractors with the knowledge and experience required to stabilise period properties with severe brickwork defects, such as superstructure issues or bowing brick walls. AWT work with property owners, structural engineers, project managers, education boards, borough councils, local authorities etc. on large and small projects.

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

Crash Damaged Ornate Stone and Brickwork Colonnade

Repairing a Car Crash Damaged Stone & Brickwork Colonnade

Impact damage from a car had severely damaged the ornate stone and brick colonnade of Chertsey’s Old Town Hall. Temporary supporting props had been put in place to stabilise the structure.

One of the ornate columns had been shunted 10cm from its original position putting the structural integrity of the masonry above in danger.

The Structural Problem

The Old Town Hall in Chertsey is a beautiful Italianate style building. It was built in 1851 and features a ground floor arcade.

When a car crashed into the ornate stone and brickwork column of this heritage property it shattered the stone base of one support column. Some of the brickwork above collapsed and the column was shunted 10cm from its base. The building was being supported by temporary props.

The Structural Repair Solution

The structural integrity of the stone and brick column needed to be restored. The ornate stone and brick arches above the column had been compromised and required strengthening. The column also required substantial realignment. All of this work needed to preserve the original appearance of the building and allowed wholesale demolition and rebuilding to be avoided.

Once additional support had been put in place, AWT designed realigning equipment was used to bring the column back to vertical alignment.

Precision drilling equipment was used to install resin bonded stainless steel pins within the arches. This reinstated structural integrity without any visible fixings. Areas of disturbed mortar were re-pointed with colour matched mortar.

c1 225x300 - Crash Damaged Ornate Stone and Brickwork Colonnade

c2 225x300 - Crash Damaged Ornate Stone and Brickwork Colonnade

c3 225x300 - Crash Damaged Ornate Stone and Brickwork Colonnade

Reinforcing was required to restore the tensile strength of the brickwork column. Grout welded bars were installed within the brickwork as well as a grip bar in the footings of the column. Selective re-building of the areas of smashed masonry with colour matched bricks and mortar completed the works and ensured the repaired column blends with the rest of the building.

The stonework base was reconstructed using some of the original stone plus repair mortar chosen to match the other columns in both colour and texture.

AWT provided an efficient and cost effective solution that avoided slow and costly demolition and rebuilding.

c4 300x225 - Crash Damaged Ornate Stone and Brickwork Colonnade

c5 300x225 - Crash Damaged Ornate Stone and Brickwork Colonnade

AWT can provide specialist stone and masonry repairs for heritage and public sector buildings in Surrey, Kent and London.

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

Concrete Cill, Mullion and Lintel Repairs

The Canterbury North Control Building, part of the UK power network infrastructure, was suffering from “concrete cancer”. Cracked and crumbling concrete window cills, mullions and lintels needed specialist concrete repairs to remedy the underlying issues and prevent further deterioration.

The Problem

AWT was contracted by AMEC Foster Wheeler to provide structural repairs on part of the UK power network infrastructure. Corroded reinforcing bars within the concrete window mullions and lintels was causing the concrete to crack and crumble from within. This is commonly known as “concrete cancer”. Weathering had also taken its toll on the concrete framework around the windows and doors.

Failing lintels and mullions can cause difficulties opening and closing doors and windows as the frames become distorted. There is also a danger of injury from falling masonry. More than superficial repairs by traditional building techniques was required.

The Solution

Action Wall Ties’ skilled operatives used specialist cutting tools to cut away larger areas of damaged concrete. Specialist tools were used to scabble the remaining areas to remove layers of loose scale, corrosion and unsound concrete.

The existing steel reinforcing bars were restored by this process to a clean, bright condition and coated with a suitable steel primer to prevent further corrosion. New stainless steel reinforcing bars were installed as necessary.

The bare concrete surface was treated with a Flexcrete 842 Bonding Bridge to prepare the surface. The damged areas of concrete were then restored using Flexcrete Monomix concrete repair mortar system. The finishing touch was achieved by applying Monolevel FC, a cosmetic grade mortar, to seal the repairs and leave a smooth surface finish ready for painting.

The concrete repairs achieved by AWT’s skilled staff restored the integrity of the masonry by getting to the root of the problem. A long term solution was provided that maintained the appearance of the property.

Greater London, Essex, Sussex and Kent are all covered by the professional services of Action Wall Ties.

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

1930s Purpose Built Library

1930s Public Library

A 1930s purpose built library in Welling, near Dartford, Kent. Corroding support angles to the flat brick soldier course lintel required bed joint reinforcement beaming, fenestration lintel repair, grout tie injection and resin bonded ties and removal of the corroding angles.

The subject building was a substantial purpose built library constructed in the mid-1930s of brick on a concrete foundation.

Structural Problems and Issues

Visible cracking and lifting movement noted to the window openings to the top floor front and two side elevations. A total of 20 windows.

The external brickwork soldier course formed a flat arch above the window openings. The flat arches were built on a 50mm × 50mm mild steel angle that was found to be heavily corroding and delaminating.

Severe corrosion of the embedded mild steel support angles and its resulting expansion had caused severe distress to the adjacent brickwork.

The internal brickwork was being supported by an independent concrete lintel.

Structural Repair Solution

AWT completed a remedial scheme, introducing bed joint reinforcement beaming, fenestration lintel repair, grout tie injection and resin bonded ties.

1. Bed joint reinforcement beaming:
The introduction of two rows of twin cord reinforcement, forming a composite deep masonry beam – as indicated with red double dotted lines on our proposal images.

2. Fenestration lintel repair:
To the underside of the fenestration openings head, we drilled for, and injected, grouted 8mm helical stainless steel pins through the brick arch, passing into the line of the composite deep masonry beam installed within the existing masonry – as indicated with green parallel lines on our proposal images.

3. Resin bonded ties:
Within the area of the beaming we drilled for (wherever possible to the centre of a brick), and resin bonded, new 6mm stainless steel remedial ties (four per square metre) above window openings, then re-pointed disturbed areas only with coloured sand and cement mortar.

After the proposed reinforcing works had been completed the windows were removed (by others) to enable the removal of the mild steel angles and making good of the brickwork.

High Quality Structural Repairs

The gallery below shows the completed structural repairs after 15 years. The repairs are as good as new.

Traditional building methods are only able to provide short term, cosmetic repairs. Our skilled structural repair specialists can identify the underlying causes of structural defects and provide long lasting repair solutions.

Councils, housing associations and other public sector organisations across the South East have turned to AWT for cost effective, long term solutions to a wide range of structural issues.

Library c2 300x225 - 1930s Purpose Built Library

Library C1 300x225 - 1930s Purpose Built Library

Library c3 300x225 - 1930s Purpose Built Library

Library c4 300x225 - 1930s Purpose Built Library

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair across Kent and London, providing professional solutions to a wide variety of structural problems and issues from cracks to wall movement and window sill defects. Contact us on 01227 721 255, or email us.

King’s Cross Station Cintec Sock Anchors

One of London’s King’s Cross station’s main entrance brick arches was sagging and losing structural integrity. AWT was contracted by Network Rail to drill for and install Cintec sock anchors to repair the structural defect.

The subject building was central London’s King’s Cross station. This Grade I listed building’s eastern large spanning brickwork entrance arch was found to be de-bonding.

Action Wall Ties was contracted to drill for, and install, Cintec cementitious grouted sock anchors to reconnect the brickwork.

This entailed drilling 75mm holes into the 225mm arched timber frame and drilling into the brickwork with a 38mm diamond drill vertically to a depth of 1200mm. We then prepared for, supplied and installed cementitious grouted sock anchors with grade 304 stainless steel M12 threaded bar washer and nut.

Action Wall Ties (AWT) are experienced structural repair contractors with the capacity to work on both large and small public sector and infrastructure projects. We can assist with a wide range of structural repairs including the installation of Cintec cementitious grouted sock anchors.

AWT are available for contracts in London, Kent, Essex, Surrey and Sussex. Please contact us via our contact form, by email or call 01227 721 255.

Hanger Lane Underpass Detached Parapets

The Hanger Lane Underpass in North West London is part of London’s North Circular Road. This vital part of the road infrastructure required specialist structural repairs because the parapets, which have very large copings, were becoming detached. Transport for London contracted AWT to install remedial fixings and stabilise the underpass.

The Structural Issues

Action Wall Ties’ expertise was sought to undertake the securing of large concrete copings to the Hanger Lane underpass retaining walls. The specification, provided by Transport for London, was to introduce a pattern of large stainless steel fixings to be drilled down into the concrete of the wall.

This presented a series of obstacles to overcome. Firstly, to enable the proposed drilling we had to initially design equipment and methods to enable the efficient drilling for the pattern of fixings. Secondly, we had to be self-sufficient for the delivery of water and electricity supply to the working place on truck mounted working platforms, together with all that is involved in working on the closure of a major road at night.

The Structural Repair Solution

To enable the efficient drilling Action Wall Ties designed and manufactured four working saddles that clamped over the head of the wall, each supporting two diamond core drilling rigs set at the correct spacings with connections for water, electricity and lighting.

To provide water to the diamond drills we mounted a large water tank and pumps with a diesel generator supplying power into a large Sprinter van, together with other mobile generators which provided the services required for the proposed works.

Works

With the access platforms in place the AWT designed manufactured drilling saddles were lifted and clamped into place and connected to the services (as listed above). Adopting wet diamond drilling techniques a pattern of 20mm holes 400mm deep were drilled. Each saddle was set in place to drill two holes simultaneously, and a second set by sliding the rig forward before resetting the saddle, deploying four maned drilling saddles to meet with the program.

The pre-drilled holes were cleaned before we resin bonded 16mm stainless steel grip bars, and made good the disturbed areas with coloured concrete repair mortar.

AWT can provide cost effective structural repairs for a wide range of structural faults including large infrastructure projects. We operate not only in London but across the whole of the South East of England. We have experience working on the road and rail network including work for Transport for London, many London borough councils and public sector organisations across the South East.

Action Wall Ties (AWT) are specialist structural repair contractors for large and small projects. Please get in touch to discuss your requirements. Contact us on 01227 721 255, or email us.

Cross Rail Projects Victorian Connaught Tunnel

Crossrail Projects Victorian Connaught Tunnel

AWT were the chosen contractors for the Crossrail project at the Victorian Connaught Tunnel in central London. Strengthening, pinning and pressure grouting techniques were used for this vital infrastructure project.

The Crossrail project was to breathe new life into the old Connaught Tunnel. It was built by the Victorians but was, at the time of this work, a disused brick-arched structure lying beneath London’s Royal Docks that survived a hit from a bomb during WW2. This was to be the only existing tunnel to be re-used for Crossrail. Works involved the widening, deepening, as well as strengthening, of the existing structure.

Action Wall Ties’ expertise and experience was sought to undertake the proposed strengthening works to the brickwork arches to the approach cutting, and the damaged area of brickwork rings that form the tunnel. This was to be carried out with the introduction of injected grout, grouted ties and pressure grouting areas where the brick work rings had separated, which was believed to be due to bomb damage.

In line with the Crossrail specification to reconnect the brickwork with the temporary supports in place we firstly drilled vertically 20mm holes 1000mm deep and injected cementitious grout, filling any contiguous voids. Once this was set we revisited the grout filled holes and re-drilled to 25mm for, and injected, cementitious grout and 16mm stainless steel bars simultaneously pinning the brickwork rings together.

After the completion of the pinning, in an attempt to fill any voids to complete the reconnection, we drilled a pattern of 16mm holes with the entrance counter drilled to receive injection packers, ready for the pressure grouting injection. With the pre-batched TamCrete MFC grout mixed and holes flushed with water we injected the grout up to 1 bar over injection pressure, until either hydraulic lock or venting grout from adjacent holes is attained.

Finally, AWT made good the entrance holes with concrete repair mortar.

AWT can provide cost effective structural repairs for a wide range of public sector and infrastructure projects. We operate not only in London but across the whole of the South East of England. We have many years of experience working on large projects, liaising with structural engineers and local authorities.

Contact AWT today to book a survey with one of our experienced team of structural repair specialists. Contact us on 01227 721 255, or email us.

Harrow High School. Corroded Window Arch Bars

Harrow High School. Corroded Window Arch Bars.

As can be seen in the photos, there were cracks in both the external brickwork and the internal plaster work around the windows of these school buildings in Harrow, Greater London. In places the external brickwork was crumbling.

The Structural Problem

The brickwork above the windows was visibly lifting and cracking. An inspection by Action Wall Ties quickly identified the cause as corroding mild steel arch bars which were reducing the support from the existing lintel arrangement. This type of fault also results in difficulties with opening and closing windows.

The flat brickwork arches in the building were of differing ages but all were built on mild steel arch bars. As these bars had rusted the resulting ferrous oxide (rust) expanded to several times the thickness of the original metal in turn lifting and cracking the brickwork above. In places the facing brickwork had crumbled to reveal the metalwork.

The Structural Repair Solution

The remedial works were designed to add tensile strength and reinstate the brickwork’s integrity without detracting from the appearance of the building.

The brickwork openings required remedial support and the arch bars needed to be removed to stop any further damage to the building. Bed joint reinforcement and beaming fenestration lintel repair techniques were used to restore the tensile strength of the masonry.

Bricks were carefully removed to allow the cutting and removal of the corroding arch bars. Two rows of twin 8mm stainless steel corded joint reinforcement fixings were installed forming a deep masonry beam. The formation of continuous beams within the existing masonry redistributes the upper storey loads and assists in restraining diagonal cracking and bulging.

Specialist drilling rigs were used to drill for and install helical stainless steel pins through the brick arch and into the line of the deep masonry beam that had been installed within the existing masonry.

Where possible the existing bricks were reused. Replacement bricks were colour matched to blend in with the original brickwork. The cracked mortar was raked out and repaired with new coloured sand and cement mortar to match the existing mortar.

Action Wall Ties serve customers not only in the Harrow area but throughout the South East i.e. Kent, Greater London, Sussex, Surrey and Essex.

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems including issues with window arches. Contact us on 01227 721 255, use our contact form or email us.