Remedial expansion movement joints Archives

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.

1950s style four-storey block of flats

A substantial 1950s style traditionally built four-storey block of flats typical of London and Kent, with bowing cracking brickwork – remedial expansion joints to solid construction

The subject buildings were substantial 1950s style traditionally built four storey blocks of flats, stepped to accommodate a sloping site.

The Structural Problem

• Visible cracking movement was noted to the front and rear elevations of each building comprising 225mm thick solid brickwork.

• The smaller of the two buildings was constructed with a central step. Cracking in line with the step was noted to the external brickwork, to the rear and to a lesser degree to the front elevations.

• The larger of the two buildings was constructed with two steps. Cracking in line with the steps was noted to the external brickwork to the rear and to a lesser degree to the front.

Discussion

The movement noted was considered attributable to seasonal moisture and the resulting thermal expansion and contraction (i.e. hygrothermal) – a predictable defect, as this large area of brickwork had been constructed without the benefit of any expansion joints.

Solution for Structural repairs

AWT completed a remedial scheme providing a viable repair through the introduction of expansion joints.

1. Flexible joints installed: We introduced crack inducement joints. With a twin diamond bladed saw, we cut a 10mm wide joint, 110mm deep, into the external brickwork between each window and thereafter installed a flexible joint – as indicated with red lines on our proposal images – all in accordance with AWT’s methods.

2. Making good: To the crack line schedule for new joints, 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.

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 on all types of properties, including Low rise housing blocks. Contact us on Canterbury 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 brickwork in 1970s low-rise blocks

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.

14-storey concrete frame block with bowing brickwork

A 14-storey concrete frame block with bowing brickwork and brick slip failing – re-tie, brick slip fixing, introduction of remedial expansion joints

The subject building was a 14-storey block of residential apartments, believed to have been constructed in the 1960s.

Problem with the brick slips

The building was of concrete frame construction. Cavity infill walls with two rows of brick slips concealed the concrete floors, forming the appearance of continuous brickwork.

The infill brickwork walls consisted of an external skin of half-brick thick stock bricks with a 60mm cavity and an internal skin of 100mm solid clinker rich blocks. The concrete floor slab was in line with the head of the window and there were two rows of brick slips that became detached from the concrete floor and in many cases had fallen.

Structural Repair Solution

Under the direction of Conisbee’s structural engineers, AWT completed a remedial scheme – which included the replacement and re-bedding of the brick slips and the mechanical fixing to the brick slips, the introduction of remedial ties and remedial expansion joints, and general brick repairs.

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems including cracked, lifting and falling brick slips on apartment blocks in the London area. Contact us on 01227 721 255, or email us to discuss your brick slip repair options.

Eight Storey Concrete Frame Block with Bowing Brickwork & Brick Slips Movement

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.

C1 300x225 - Eight Storey Concrete Frame Block with Bowing Brickwork & Brick Slips Movement

C2 300x225 - Eight Storey Concrete Frame Block with Bowing Brickwork & Brick Slips Movement

C4 300x225 - Eight Storey Concrete Frame Block with Bowing Brickwork & Brick Slips Movement

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.

Bulging Brickwork and Brick Slips on 60s /70s Apartment Blocks

Concrete frame blocks of social housing in Wandsworth, London with clearly visible bowing to the brickwork and infill brick slip. Defective support to infill wall with cracked and detached brick slips.

The Structural Problem

The structural survey report on this South West London social housing block

The survey of these circa 1960s/1970s blocks of flats revealed, that due to a construction defect, the external brickwork had insufficient support. AWT also found heavily corroded wall ties plus a lack of weep vents and no horizontal expansion joints.

The infill wall external brickwork was originally only supported onto the concrete floor beam by less than 50mm. Where the wall had bulged outward this was reducing the support to just 30mm with the loads onto the brick-slips causing them to bulge out.

Our Structural Repair Solution

The infill wall brickwork was leaning and in danger of becoming detached. AWT promptly made the elevation floor safe (erecting a scaffold to provide access) by installing AWT’s specially developed props.

The remedial work included:

Installation of stainless steel support angles and cavity trays
Clearing debris from the wall cavities
Rebuilding the brickwork by removal, re-bedding and fixing of brick slips
Installation of stainless steel wall ties
Provision of horizontal expansion joints.

Repair and Replacement of Brick Slips

The original bricks and brick slips were reused when possible. Replacement bricks, mortar and sealants were colour matched to maintain the visual integrity of the apartment blocks.

Action Wall Ties are the apartment block structural repair specialists. Our brick slip and wall tie replacement solutions are available to clients in the South East i.e. in London & in Kent, Sussex, Surrey & Essex.

Action Wall Ties (AWT) are specialists in structural repairs to concrete framed buildings and tower blocks. From movement issues to wall tie replacement and brick slip repairs. We provide specialist professional solutions to a wide variety of structural problems. Contact us on 01227 721 255, or email us.