Corroding brickwork support tie bars, angles and embedded mild steel cracking brickwork Archives

Hazardous Masonry on Grade 2 Listed Building

Listed Building with Bulging & Cracking Masonry

This Grade II listed building in Thanet, Kent, was built in the 1840’s. The owners of this period property were facing the prospect of demolition and rebuilding of the facade of the property due to serious structural defects. Previous repairs using standard building techniques had failed to solve the structural problems. The property is currently in use as a nursery school. The business would have been forced to close for several months during traditional building works. AWT were able to repair the severe structural problems in a couple of weeks and preserve the period features without disrupting the running of the business.

The Structural Problem

The structural issues with this Victorian, Grade 2 listed property in Ramsgate, Kent were becoming hazardous due to the risk of falling masonry. Traditional building methods would have required several months of expensive and messy deconstruction and rebuilding work. The business would have been forced to close during the building works and the subsequent re-plastering and redecoration.

The front of the building had clearly visible bulging and cracking to the head of all the first floor windows. There were also cracks in the brickwork and stucco works each side and to the underside soffit of the window opening heads. There were clear signs of previous attempts at repairs that had failed to get to the root cause of the problems.

grade 2 listed structural defect - Hazardous Masonry on Grade 2 Listed Building — Buckling Brickwork

As shown in the photo below, the mild steel embedded within the masonry had corroded and the rust caused it to expand to several times the thickness of the original metal. The heavily corroded wrought iron arch bars were lifting and cracking the brickwork and the decorative stucco around the windows. The stucco stringer course frieze and cornice of the parapet wall was also cracking and distorting. Previous attempts at repairs had provided a temporary, cosmetic repair but had failed to solve the underlying structural defects.

The continued expansive corrosion of the wrought iron arch bars would, without remedial works, lead to the failure of the masonry and the risk of detached masonry falling from the building. Urgent structural repairs were required.

Rusting wall bars 300x225 - Hazardous Masonry on Grade 2 Listed Building

Rusted metal grade2 listed 300x225 - Hazardous Masonry on Grade 2 Listed Building

The Structural Repair Solution

Structural repairs to listed buildings need to be handled carefully to preserve the period features of the building. AWT have many years of experience working on listed properties. AWT can help the owners of listed buildings to navigate through the process of obtaining permission for repair works.

The specialist tools and techniques that AWT employ allow structural repairs to be made without the need for visible fixings. Using custom designed drilling and cutting tools, AWT can remove corroded metal fixings and embed new stainless steel fixings within the masonry.

In order to allow the business to remain open during the structural repair works, AWT arranged for the scaffolding to be erected at the weekend while the nursery was closed. The scaffolding was then double boarded and netted for safety. The AWT crew accessed the scaffolding from the side of the building allowing parents, children and staff to access the building as usual through the main entrance.

vertical wall ties 225x300 - Hazardous Masonry on Grade 2 Listed Building — Preparing Vertical Wall Ties

grade 2 listed structural works 225x300 - Hazardous Masonry on Grade 2 Listed Building — Drilling for Vertical Wall Ties

The AWT team used their specialist techniques to form composite beams within the existing brickwork and then remove and replace the corroded wrought iron arch bars. The team then reconnected and reinforced the brickwork above the windows and the parapet wall. They also repaired the cracked decorative stucco.

Before metal grade2 listed 225x300 - Hazardous Masonry on Grade 2 Listed Building — Before – Cracks & Broken Bricks

replacement lintel Thanet Kent 225x300 - Hazardous Masonry on Grade 2 Listed Building — During – Lintel Replaced

After metal grade2 listed 225x300 - Hazardous Masonry on Grade 2 Listed Building — After – Ready to Paint

This project required a combination of:

Bed joint reinforcement beaming
Grout tie injection
Resin bonded ties
Cintec sock anchors
Removal of corroded mild steel arch bars
Replacement arch bars
Brickwork repairs

The team at AWT strive to make all works as sympathetic as possible with the existing masonry. Not only do they try to match replacement bricks and pointing for colour and style they even match the mortar mixture texture.

The high quality fixings used by AWT combined with their thorough knowledge of structural defects ensures a long term solution to structural issues.

Action Wall Ties are structural repair contractors with the specialist skills required for listed buildings. AWT work along with property owners, architects, project managers and local authorities to preserve historic buildings.

AWT are available for large and small projects 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.

Bed Joint Reinforcement Beaming

Victorian property in Hampstead, NW3. Three-storey bay windows with pulling away outward movement, dropping brickwork (all with previous failing repairs) and bowing side flank wall. Repaired using bed joint reinforcement beaming, lateral restraints, crack stitching, and resin bonded ties.

The subject building was a substantial Victorian end-of-terrace domestic residence in North West London.

Structural Problems

Outward movement to the gable wall, patress plates and tie bars were noted, which indicated that a previous attempt to restrain the outward movement had been made. No significant cracking was noted. Also, a steel band to the front bay window on the first and second floors was found to be heavily corroded and delaminating.

Causation

The movement noted is progressive, attributable to historic subsidence (downward movement) compounded by outward movement due to ineffective or inadequate restraining to the main elevational walls and the bay window, allowing the brick arch to spread and drop and the brickwork above to crack.

Structural Solutions

AWT’s remedial scheme was to introduce bed joint reinforcement beaming, lateral restraints, crack stitching and resin bonded ties – adding tensile strength and restraint and thus reinstating the brickwork’s integrity and the uniformity of the wall.

After installation, pointing was raked out, reinstated and tinted to match the existing (see coloured remedial works on our proposal picture).

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

2. Lateral restraints:
In conjunction with the beam, 8mm stainless steel lateral restraints were introduced and screwed directly into the timber floor joists’ end grain or into the side grain, all resin bonded to the masonry – as indicated with yellow stars on our proposal images.

3. Crack stitching:
To stitch localised cracks, single 8mm stainless steel corded joint reinforcements were introduced – as indicated with red single dotted lines on our proposal images.

4. Wall ties to de-bonding brickwork:
Wherever possible, we drilled for and resin bonded 6mm stainless steel remedial ties to the centre of a brick. We then re-pointed the disturbed areas with a coloured sand and cement mixture – as indicated with blue line on our proposal plan images.

5. Making good and pointing:
We then raked out the existing 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.

High Quality Structural Repairs

The photo below shows the completed structural repairs 14 years after the project was completed. Unlike the previous repairs by traditional builders, AWT’s structural repair techniques got to the root of the problem.

AWT provide long lasting, cost effective structural repairs so you can enjoy your home.

Read our frequently asked questions about bay window structural repairs.

Action Wall Ties (AWT) based in Kent are specialists in masonry reinforcement and repair covering London, Kent and the whole South East area. AWT provide 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.

Cracking 18th Century water tower

Substantial cracking brickwork to 18th Century water tower due to corroded mild steel – reinforce, remove corroding steelwork and make good

This building is an interesting 18th century purpose built water tower constructed to service a country estate with running water.

Problem: Cracking brickwork

AWT was contacted by the owners of the water tower with concerns about significant cracking to the brickwork.

On inspection we noted that there was indeed substantial cracking and distortion to the external brickwork, together with corresponding internal cracking.

The cracking noted appears to originate from the embedded mild steel.

case 41 b 1 230x120 - Cracking 18th Century water tower

case 41 b 230x120 - Cracking 18th Century water tower

case 41 a 1 230x120 - Cracking 18th Century water tower

case 41 d 2 230x120 - Cracking 18th Century water tower

case 41 d 1 230x120 - Cracking 18th Century water tower

case 41 d 230x120 - Cracking 18th Century water tower

case 41 c 3 230x120 - Cracking 18th Century water tower

case 41 c 2 230x120 - Cracking 18th Century water tower

case 41 c 1 230x120 - Cracking 18th Century water tower

case 41 c 230x120 - Cracking 18th Century water tower

case 41 b 8 230x120 - Cracking 18th Century water tower

case 41 b 7 230x120 - Cracking 18th Century water tower

case 41 b 6 230x120 - Cracking 18th Century water tower

case 41 b 5 230x120 - Cracking 18th Century water tower

case 41 b 4 230x120 - Cracking 18th Century water tower

case 41 b 3 230x120 - Cracking 18th Century water tower

case 41 b 2 230x120 - Cracking 18th Century water tower

case 41 e 2 230x120 - Cracking 18th Century water tower

case 41 e 230x120 - Cracking 18th Century water tower

case 41 e 1 230x120 - Cracking 18th Century water tower

Causation

The cracking noted was found to be progressive, mainly due to expanding corrosion from the mild steel RSJ’s lifting and cracking the brickwork and stone work, together with a combination of ageing, seasonal moisture, thermal expansion and contraction (i.e. hygrothermal).

Corrosion of the embedded mild steel resulted in the formation of ferrous oxide that expanded to several times the thickness of the metal it had resulted from, thus breaking out the brickwork and causing lifting and bowing of the walls.

Structural repair solution

Our proposed remedial scheme was to provide a viable repair by firstly removing the corroding mild steel, thus addressing the causation, and thereafter introducing bed joint reinforcement beaming, crack stitching, and lateral restraints to reconnect and restrain the brickwork, together with brickwork repairs to reinstate the uniformity of the wall and apply dry seal.

Starting at the top level and repeating to the lower levels we provided working platforms to accommodate the proposed works, installing temporary support with AWT developed props to brace the steel beams and allow for the removal of the embedded mild steel channels and RSJ’s, together with the removal of the surrounding brickwork.

We then replaced the removed channel with suitable bricks.

Once the brickwork was set the horizontal bed joint between the rebuilt and original brickwork was dry packed providing a supporting connection.

To maintain lateral restraining we drilled the masonry for, and resin bonded, stainless steel 12mm grip bars together with brickwork repairs.

To reconnect the brickwork we installed rows of twin 8mm stainless steel corded joint reinforcement, forming a deep masonry beam to stitch localised cracks and to add cohesion and tensile strength to the brickwork.

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.