Wall tie treatment and weather struck re-pointing to 1950s style two-storey semi-detached house of the type typical of Kent and London.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Large expanse of brickwork with extensive cracking
Contemporary terrace of houses with large expanse of brickwork with extensive cracking – introducing remedial movement joints and repair the cracking brickwork.
The subject buildings were a terrace of domestic residences of cavity construction, circa 1970s typical of London and Kent.
The Structural Problems
Our inspection revealed many significant cracks to and from windows and to the lower valley of the roofs, along with evidence of many previous repairs. No expansion joints were noted.
Discussion
The cracking noted was not attributable to significant subsidence but to seasonal moisture, thermal expansion and contraction (i.e. hygrothermal).
This considerable length of continuous brickwork had been constructed without the benefit of any expansion joints.
Structural Repair Solution
AWT completed a structural repair / remedial scheme that provided a viable repair by introducing expansion joints, bed joint reinforcement beaming and crack stitching.
With a hydraulic twin diamond bladed saw we cut a 10mm wide joint to the full depth of the external skin and thereafter formed a flexible joint, all in accordance with AWT’s methods.
Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems in London and Kent. Contact us on 01227 721 255, or email us.
Cracking to brickwork façade to 1970s low-rise blocks with short wall returns – install remedial expansion joints
The subject buildings are 1970s low-rise blocks of domestic apartments in North London of conventional brick built construction, featuring a stepped out entrance section leading to a central stairway.
Detailed Case Study:
The buildings are three-storey blocks with a repeating front façade, featuring a stepped out entrance section leading to the stairway serving wings either side.
Each short wall return (dogleg) protruding corner has been largely rebuilt and further cracking to the junction to both rebuilt and old brickwork was noted.
One of the buildings with two entrances totals some 40 metres in length.
Cause of the Structural Problems
The returns are approximately 450mm. It was recognised that short wall returns (dogleg) on these long façades have performed as one long span with regard to hygrothermal movement, and this has resulted in cracking to the front corner to both old and rebuilt brickwork.
Discussion
From Action Wall Ties’ findings it is apparent, bearing in mind the large area of brickwork façades that have been constructed without the benefit of any expansion joints, that the cracking noted is due to seasonal moisture, thermal expansion and contraction i.e. hygrothermal movement.
Structural Repair Solution
Action Wall Ties’ remedial works are designed to provide a cost effective, long term solution ameliorating all the defects noted, retaining the existing appearance of the brickwork with the minimum of disruption to occupants and impact on the environment.
Action Wall Ties completed a remedial scheme that provided a viable repair by introducing expansion joints, bed joint reinforcement crack stitching.
Action Wall Ties’ experienced skilled operatives installed remedial wall ties either side of the joint before fixing the saw track to the wall and connecting a hydraulic twin diamond bladed saw set to cut a 10mm wide joint to the full depth of the external skin.
Action Wall Ties services are available to clients in the South East i.e. in London, Kent, Sussex and Essex.
Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional structural repair solutions to a wide variety of structural problems from brickwork cracks to more serious movement. We can retrofit new expansion joints, repair cracks and stabilise walls with a minimum of disruption or fuss. Contact us on 01227 721 255, or email us.
Eight Storey Concrete Frame Block with Bowing Brickwork and Brick Slips Movement
Five circa 1950/60s eight storey blocks of concrete frame construction with cavity brickwork infill walls in London SW19. Bowing brickwork and brick slips movement, due to concrete frame shortening. Repaired by some rebuilding brickwork and brick slips fixed insitu – mechanically fixed with Action Wall Ties designed method .
The subject development comprised of five circa 1950/60s high-rise blocks of flats in South West London. The blocks are of concrete frame construction with cavity brickwork infill walls below windows and full height to flank elevations.
The Structural Problem
The infill cavity brickwork walls were constructed with an external skin of LBC type bricks, 75mm to 95mm cavity, and a hollow clay pot internal skin.
The infill walls were constructed from each concrete floor beam to the underside of the floor beam above with approximately 65mm support to the external brickwork.
This left 40mm protruding to accommodate six/seven courses of 35mm brick slip bedded onto the floor beam, forming the appearance of continuous brickwork. The bricks have weathered well, with little sign of spalling, though some damaged bricks were noted.
The manufactured brick slips were 35mm thick with a bedding groove to the rear.
The brick slips were bedded down onto the last brick course of the infill wall and onto the face of the concrete beam, with sand and cement mortar up to the first course of the brick wall above (no horizontal soft joints were found).
A cast-in wire butterfly tie was uncovered that had not been bent out and bedded into the mortar as intended. Previous repairs, bulging leaning movement, and hollow and missing brick slips were all noted.
Hollow clay blocks formed the internal skin of the cavity walls constructed in-between the concrete floor/beams and columns.
The wall ties were found to be galvanised vertical twist, generally adequately bedded, clear of building debris, installed to a good pattern and of adequate density.
No head restraints were located with the last row of ties six/seven courses down from the head of the wall. No significant corrosion to the existing ties was noted.
Discussion
We found that the buildings had generally performed well, including the buildings’ brickwork infill walls, with the exception of the brick slips and the head of the infill walls.
Since the buildings had been completed, the concrete used in their construction had shrunk, the concrete frame had shortened and the bricks’ first irreversible expansion had taken place.
Where brickwork and concrete frame abut these opposing stresses were putting the brickwork in compression, locking in the brickwork to the continuous brick slips to the flank walls.
This effect was further augmented by thermal expansion, especially to the south-facing walls.
Where the walls were not adequately tied the compression force had been released laterally, causing bulging and leaning of the brick slips and the head of the wall down to the first row of effective ties.
Most of the brick slips had become detached from the concrete beam, probably due not only to the compression force described above but to differing movements and poor fixing details. Modern-day standards require a mechanical fixing to each brick slip.
Long Lasting Structural Repair Solution
AWT completed a remedial scheme providing a viable repair by rebuilding sections of the brickwork and brick slips, introducing a pattern of mechanical fixings to the brick slips and angled head restraints along with a number of horizontal soft joints.
The gallery below shows the blocks 13 years after work was completed. The quality repairs by AWT are still going strong. In the long term, quality structural repairs provide better value for money than repeated, ineffectual repairs using traditional building methods.
All of our work to low and high rise blocks follows the guidelines provided by the British Standards Institution and the Building Research Establishment Specification Digest.
Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of low, mid and high rise block structural problems.
AWT work with councils, housing associations, project managers and architects across London, Kent, Surrey & Sussex.Contact us on 01227 721 255, or email us.
Grade 2* listed Spa Green Estate in London EC1, designed by Bertholt Lubetkin. Extensive remedial reinforcing including work to the hit and miss vents, brick slips and widespread brickwork repairs.
Spa Green Estate is a public housing estate in central London designed by Bertholt Lubetkin and Grade 2* listed in 1998.
It is widely viewed as being the finest example of public housing of its type, but remedial works were required and Action Wall Ties were engaged to undertake elements of the project.
Extensive remedial reinforcing was required including work to the hit and miss vents, brick slips and widespread brickwork repairs.
AWT operatives were made aware of the importance of the buildings and accordingly ensured that all works were carried out with the appropriate level of care and respect for the structure, and were completed to be sympathetic with the Grade II* facade all to the approval of English Heritage.
Long Lasting Structural Repairs
The After photos in the gallery below shows the building 14 years after the work was completed. This shows the quality of workmanship provided by AWT.
During Remedial Work
After Remedial Work
After Remedial Work
After Remedial Work
After Remedial Work
After Remedial Work
Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems on Grade 2 Listed Buildings in Kent, Surrey, Sussex and London. Contact us on 01227 721 255, or email us.
Failing and Rotating Victorian Pentagon Bay Window
Unstable Victorian pentagon bay window. The masonry of this 5-sided bay window was failing and rotating. It required stabilising, realignment and reinforcement. AWT was able to restore the structural integrity of the ornate period bay window without slow and expensive rebuilding work.
The bay window at the corner of this end-of-terrace domestic Victorian property was in danger of collapse. There was significant visible outward leaning movement and the dropping of the brickwork arches in the pentagon bay window.
The Structural Problem
This two-storey, pentagon-shaped (also known as 5 lite/5 panel/5 pane) bay window with a brickwork crenellated parapet wall was found to be unstable. It suffered from rotational outward movement, dropping of the brickwork arches at ground floor level, and significant rotational outward movement to the masonry columns, causing spreading and dropping of the brickwork arches above, which was of great concern.
Sagging Bay Brickwork
Cracking Brick Arches
Gaps & Cracks
Dropping Brick Arches
Collapsing Brickwork
Leaning Bay Window
The structural defects in the bay window were having a knock-on effect on the rest of the house. Similar movement was reflected in both the front and left side elevations, with outward bulging noted and some cracking of the front ground floor arches.
The movement noted by the AWT survey team was progressive and advanced. The structural failings were attributable to ineffective, inadequate restraining to the bay window structure, This has allowed the masonry columns to bulge outwards and the brick arches to spread and drop, cracking the brickwork above and becoming unstable and in danger of collapse.
The Structural Repair Solution
Action Wall Ties proposed remedial scheme was to provide a viable repair by realignment and then introducing Bed Joint Reinforcement Beaming. Other structural repair techniques were also used including:
brickwork arch lintel repair
lateral restraints
special diamond drilling for grout tie injection
resin bonded ties
This combination of specialist structural repairs enabled the AWT team to reinstate the uniformity of the wall and provide restraint to the masonry.
We provided temporary support to the underside of the ground floor, then the underside of the first-floor window brick arches, removed debris from the cracks and deployed AWT designed and developed realigning cramping equipment to realign the masonry elements, closing open joints and returning the arches back to a more level line with the adjacent brickwork, along with the masonry columns, and into a more upright line before proceeding with the proposed drilling and reinforcing.
As indicated with red double dotted lines on our proposals 1, 2 & 3, we introduced twin 8mm stainless steel corded joint reinforcement, forming a deep masonry beam.
As indicated with horizontal green parallel lines on our proposals 1, 2 & 3 to form the beam and reconnect the bay window elevational brickwork, once the brickwork had been realigned with AWT-designed drilling equipment we diamond drilled a 20mm hole through each elevation of the bay, through the main elevational wall and chased internally into the main elevation wall, injecting a grouted 8mm helical bar.
As indicated with vertical green lines on our proposals 1, 2 & 3, to the underside of the fenestration openings head, we drilled for, and installed, grouted 8mm helical stainless steel pins through the brick arch and passed them into the line of the deep masonry beam, installing them within the existing masonry.
As indicated with yellow stars on our proposal 2, we drilled for, and screwed directly into timber floor joists, 8mm stainless steel lateral restraints, all resin bonded to the masonry.
As indicated with vertical green parallel lines on our proposals 1, 2 & 3, once realigned and columns made more upright, we drilled with specially designed drilling rigs from the top of the parapet down through brickwork and passed into the top of the masonry columns in order to inject a grouted 12mm stainless steel grip bar.
For cracked brick arches scheduled for reinforcement listed above, we raked out the existing cracked mortar and repaired it with new coloured sand and cement mortar to approximately 20mm in depth.
Action Wall Ties have developed methods and trained skilled experienced operatives to strive to finish our work to always be sympathetic to the existing structure. Where possible AWT match replacement bricks, pointing style and mortar mixture for texture and colour.
Restored Pentagon Bay
Realignment of Brickwork
Realignment of Bay
Bay Window Repair
Reinforced Bay Window
Restored Bay Masonry
Period Bay Repairs
5-Pane Bay Repairs
Bay Window Crack Repair
As can be seen in the gallery images, AWT’s specialist structural repair techniques were able to save this beautiful pentagon bay window. The period features were preserved. A long-lasting repair to the structure was achieved without any visible fixings and without rebuilding work.
Restoration of Collapsing Bay
Restoration of Period Bay
Structural Repairs to Period Bay
Action Wall Ties services are available to clients in the South East i.e. in London & in Kent, Sussex & Essex. We regularly rectify problems and issues relating to cracking and movement around bay windows in properties of all ages and types.
Action Wall Ties (AWT) are specialists in bay window reinforcement and repair, providing professional solutions to a wide variety of structural problems. Contact us on 01227 721 255, or email us.
