Cracked balustrade brick walls due to expansive corrosion of embedded mild steel components 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.

1930s style low-rise apartment blocks

1930s style low-rise apartment blocks in London

An estate of 1930s style low-rise blocks of apartments with defective balustrade walls (half-brick thick) to access deck and private balconies – AWT’s remedial scheme – remedial restraint posts, removal of the existing reinforcing rebars.

The subject buildings are 1930s style low-rise blocks of apartments, conventionally built of solid brickwork and concrete floors, with open access decks and private balconies.

Structural Problems

• Visible cracking and previous repairs (in a similar pattern) were noted to the balustrade half-brick thick walls.

• Generally the brickwork and pointing was found to be in good condition, with little spalled pointing and bricks noted. Previous repairs to the access decks and private balconies balustrade half-brick thick walls in a similar pattern were noted.

• All access decks and a representative sample of private balcony balustrade walls were inspected and scanned, locating the reinforcing bar position. Some bars were uncovered, inspected and photographed. In the main, previous repairs correspond to the pattern of the existing reinforcing bars.

• The reinforcing bars uncovered were the old ½ inch rebar bent up from the concrete slab and built into the centre of the brickwork up to, and possibly into, the cast in-situ concrete coping.

Discussion

The existing half brick balustrade walls contained mild steel reinforcing bars. From our investigations it was apparent the damage to the brickwork (cracking/spalling/previous repairs) resulted from the expansive corrosion of these bars which reduced the effectiveness of the bar, especially at the asphalt tuck line leaving the wall vulnerable to failure represent a safety issue.

The reinforcing bars viewed had corroded, delaminated and expanded, rendering the bars ineffective. The half-brick thick balustrade wall’s stability is dependent on the reinforcing.

Wrought iron decorative panels, built in lugs viewed, assessed to be corroded, delaminated and expanded, lifting and cracking the brickwork.

Stuctural Repair Solution

AWT have previously successfully completed remedial schemes to ameliorate similar defects at many other blocks.

AWT’s remedial scheme involved the development of methods and the design of equipment to enable us to undertake the remedial reinforcement, installing restraint posts, expansion joints, removal of the existing reinforcing rebars and thereafter make good the brickwork to the balustrade walls, to the access decks and to the private balconies.

The remedial scheme also alleviated the need for the removal and replacement of the balustrade walls, along with all the associated problems that this would have entailed for the occupants with the added benefits of a considerable cost saving and resulting impact on the environment.

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

1930s style low-rise apartments with balustrade wall defect repairs

An estate of 1930s style low-rise blocks of apartments with balustrade wall defects – corroding mild steel balusters cracking masonry to half-brick thick balustrade walls – removal of the baluster embedded into the coping stone and brickwork,

The subject buildings are 1930s low-rise blocks of apartments in London, of conventional brick and filler joists construction, with open access decks and private balconies.

The Structural Problem

Cracking and dislodging of the brickwork and coping stones to the balustrade walls of the private balconies was reported and noted.

Discussion

Action Wall Ties investigated the defects and reported that the causation was found to be due to expanding corrosion of the handrails mild steel supporting balusters built into the masonry.

The corrosion of the embedded mild steel results in the formation of ferrous oxide that expands to several times the thickness of the metal it has resulted from, thus breaking out of the brickwork splitting bed joints and lifting of the brickwork.

Structural repair solution

Action Wall Ties remediation involved cutting the baluster at the coping stone line, removal of the baluster embedded into the copping stone and brickwork, and completing repairs to the brickwork and coping stone. AWT re-drilled holes down into the walls for grout and designed all the necessary stainless steel fixing plates, thereafter welding the original baluster to a fixing plate.

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

Balustrade wall defects

Balutrade wall defects in West London

An estate of 1930s style low-rise blocks of apartments in West London with balustrade wall defects – remedial restraint posts to walkway balustrade walls, cutting expansion joints

The subject building is part of an estate of 1930s style low-rise blocks of apartments in West London of conventional brick and filler joists built construction with open access decks and private balconies.

Problems with cracks in the Balustrade walls

This very large building is curved with convex walkway balustrade walls.

Outward stepping at the base of the walls, together with outward leaning and cracking of the brickwork and coping stones to the walkways’ balustrade walls, was reported and noted.

Discussion

Action Wall Ties investigated the defects and reported that the causation was found to be due to seasonal moisture, thermal expansion and contraction i.e. hygrothermal movement.

The expansion had pushed the walls outwards, in some cases stepping out the base of the wall and the wall leaned outwards.

Structural repair solution

Action Wall Ties remediation works are designed to provide a cost effective long term repair solution, ameliorating the defects noted, that retains the existing appearance with the minimum effect to the occupants and impact on the environment.

To stabilise the balustrade wall Action Wall Ties completed remediation, involving cutting expansion (movement) joints and the design fabrication and fixing of restraint posts.

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

1970s style low-rise block with defects to balustrade walls on balconies

1970s style low-rise blocks with defects to balustrade walls on private balconies – a combination of single corded bed joint reinforcement, AWT diamond drilled for grouted stainless steel pins, removing the existing reinforcing bars, cut handrail and injected grouted steel pins to repair.

The subject building is a 1970s style low-rise block of domestic apartments in South East London, of conventional construction with open access decks and private balconies.

Rusting of steel reinforcing bars and the handrail baluster fixings had caused potentially dangerous cracking of the balcony walls.

Action Wall Ties’ solution for fixing the cracked brickwork involved reinforcing the brickwork.

The rusted reinforcing bars and other corroded steelwork balusters were removed to prevent further cracking. New stainless steel fixings designed by Action Wall Ties were then fitted and the balcony walls were rendered and made good.

Detailed Case Study:

Balcony Problems & issues

Visible cracking of brickwork and previous repairs (in a similar pattern) was noted to the inside of the balustrade ½ brick thick walls to the private balconies.

The balconies’ balustrade walls were all of a similar construction – ½ brick thick stretcher bond brickwork, with faced brickwork externally and render finish to the inside.

They were finished with a concrete coping stone and a steel tubular handrail supported by tubular balusters embedded through the coping stones down into the first two courses of brickwork.

Generally the external bricks and pointing were found to be in good condition with little spalled pointing and spalled bricks noted.

There was visible cracking and previous repairs in a similar pattern to the internal render finish, and cracking to the coping stone and first two courses in line with the embedded steel baluster.

Action Wall Ties’ inspection revealed a heavily corroding 10mm mild steel reinforcing bar, set into the concrete slab adjacent to the brickwork and fixed to the brickwork with mild steel wire ties bent round the upright bar and built into the brickwork bed joint.

The cracking and previous repairs noted corresponded with the reinforcing bars built into the render finish.

In line with the embedded tubular handrail baluster some cracked bed joints and dislodged coping stones were noted.

In some cases the cracking continued down through the first two courses of brickwork, in line with the depth of the embedded baluster. The coping stones have no mechanical fixing required by modern day standards.

Discussion

From Action Wall Ties’ findings it is apparent that the cracking to the render finish and cracking to the coping stones and brickwork noted above were due to two generic defects – that of the advanced expanding corrosion to each of the embedded reinforcing bars and the handrail tubular baluster.

The brickwork has admitted moisture, resulting in expanding corrosion (i.e. the formation of ferrous oxide that expands several times the thickness of the metal it has resulted from) on the embedded mild steel, thus cracking brickwork and further fuelling the process by reducing the section of reinforcing bar and the effectiveness of the reinforcing bars.

The ½ brick thick balustrade wall’s lateral stability is dependent on this reinforcement.

The brickwork has admitted moisture running down from the baluster into the masonry resulting in expanding corrosion to the mild steel baluster, thus cracking the brickwork and dislodging the coping stones further fuelling the process.

From our findings an engineering appraisal and remedial strategy was adopted.

The judgment was to determine the extent of the remedial works that should be instigated to accommodate a maintenance program and safety issues assessment.

Structural Repair Solution

Action Wall Ties’ remedial works were designed to provide a cost effective, long term repair solution ameliorating all the defects noted, retaining the existing appearance with the minimum of disruption to occupants and impact on the environment.

Our proposed remedial scheme provided a viable repair with the introduction of a combination of single corded bed joint reinforcement – to remove the handrail and baluster from the brickwork, drill for and grout in AWT designed stainless steel fixings, cut and weld original handrail in place.

AWT Diamond drilled the full height of the balustrade wall into the concrete slab and injected grouted stainless steel pins, removing the existing reinforcing bars from the brickwork and made good the render, drilled for resin bond stainless steel ties and made good coping stones.

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, replacing corroded embedded steel and re rendering the surface, providing professional solutions to a wide variety of structural problems in the south east including Kent and London. Contact us on 01227 721 255, or email us.