Concrete frame building infill wall remedial supports angles, dowels Archives

Concrete Frame Remedial Works

Inspection of this 9 storey concrete frame tower block revealed serious defects in the previous remedial works by another company. AWT installed remedial head restraints and wall ties to restore structural integrity.

The Structural Problem

This circa 1970s nine storey social housing apartment block in Dagenham that was over clad some two years previously with a polystyrene insulation system, that was deemed unsafe and removed to be replaced with PermaRock mineral Fibre EWI system. AWT was contracted to undertake an intrusive inspection of the wall ties, head restraints and visible concrete elements.

This concrete framed building’s cavity infill walls rely on wall ties to provide a degree of interaction between the two leaves, increasing vertical load and resistance to lateral movement (generally wind load) than two leaves acting separately and head restraints to tie the inner and outer walls to the concrete frame. Sound, correctly installed wall ties and head restraints are vital to the structural stability.

The British Standards Institution and the Building Research Establishment Specification Digest provide clear guidelines for the fitting of wall ties and head restraints in concrete framed buildings. Not only must the appropriate type and size of wall tie and head restraint be fitted but the number of fixings per square metre and the pattern of fixings within the masonry must also be considered.

Our Structural Repair Inspection

The AWT inspection comprised a limited inspection of the existing wall ties by drilling 12mm holes in the outer leaf of the brickwork to view within the cavity using an Endoscope. A metal detector was used to establish the remedial wall tie density and distribution and condition.

Our inspection revealed the original wire butterfly wall ties were in poor condition and found to be over their useful lifespan. Many of the original wall ties were also incorrectly installed or not embedded at all.

The remedial wall ties installed to replace the original butterfly ties were installed poorly and with insufficient population. Insufficient or incorrectly fitted head restraints dramatically reduce the load bearing capacity of the brickwork. If wall ties are broken, missing or incorrectly fitted this can allow the masonry to bow and crack.

The remedial wall ties were installed in an erratic pattern rather than the recommended pattern for maximum load capacity. The majority of the remedial wall ties had been installed in the mortar bed joints rather than into the bricks. The wrong length of ties had been fitted and insufficiently resin bonded. Many of these wall ties could be removed by hand!

The head restraint fittings were also incorrectly fitted with many being too long and protruding out of the brickwork rather than being securely fixed within the masonry.

The Structural Repair Solution

AWT provided high quality remedial work that is designed to last. Our skilled operatives take pride in their work and are committed to ensuring that every project they complete is safe.

High quality remedial ties were carefully installed in the correct pattern and density. Head restraints were also fitted to restore structural integrity.

AWT provide cost effective, safe remedial repairs to concrete framed buildings throughout London and the South East.

To book a time for one of our surveyors to visit your property, call us today on 01227 721255, email us at enquiries@actionwallties.co.uk or use our contact form to get in touch.

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.

Failing concrete support toes

Twelve storey concrete frame building with failing concrete support toes – install stainless steel angles reinforcement and re-tie infill walls

The subject of this case study was a 12-storey concrete frame building with brick infill walls believed to have been constructed in the 1960s.

Problem: Cracks and failing concrete toes/wall ties

The building was of a concrete frame and floor construction, with cavity brickwork infill walls. The infill walls were constructed with an external brick skin on a single course high concrete toe that was visible above the fenestration openings and balcony soffit.

a. Cracking movement was noted to the infill walls.

b. Sections of the concrete toes were found to be failing, along with sections of the external brickwork not supported by the concrete toe.

c. A wall tie deficiency was evident.

Solution – Concrete Repair

AWT completed a remedial scheme, providing a viable repair by the introduction of 10mm stainless steel reinforcement to the concrete toe, remedial wall ties and general brick repairs. Establishing our reputation as a quality concrete repair company.

Making good and pointing: 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 a specialist concrete repair company, working with concrete, and offering masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems. Contact us on 01227 721 255, or email us to discuss your concrete and masonry cracks and issues for a quote and simple quick and reliable solution.

1980s Office Building with Failing Brick Slips

Imposing 1980s quadrangle designed head office building in Essex with failing brick slips. The contract for remedial fixing of the brick slips was awarded to Action Wall Ties.

The subject building was an imposing 1980s quadrangle design commercial head office building, over four floors, in four wings with entrance towers to each corner.

This building was undergoing a major refurbishment for new occupants Cofunds when some detached brick slips were noted. Action Wall Ties was invited by Como Interiors to undertake an inspection of the brick slips and any associated defects, and to report our findings and recommendations.

Action Wall Ties inspected Mayland house building, identified the defect, reported on our findings and recommended AWT designed fixing of some 20,000 brick slips.

Action Wall Ties was instructed and successfully completed the fixing of 20,000 brick slips to this building on budget and on program. Our work met with the approval of both Como and Cofunds.

The Structural Problem

The building was found to be of concrete frame construction, with cavity brickwork infill walls, an external skin of stretcher bond reddish multi-stock bricks constructed on each concrete floor beam with brick slip facing, and with windows up to the underside of the floor beam above in-between brick clad columns.

The external brickwork infill walls were found to be supported on the floor beam by approximately 60mm, with 50mm protruding to accommodate finishing and with brick slips bedded in front of the concrete floor beam, thus giving the appearance of brickwork. To each wing the brick slips formed a full brick soldier course with three courses of stretcher bond to the return wall and the entrance towers.

Since this building was built the concrete frame had shortened, and the bricks’ first irreversible expansion had taken place. We believed that these movements, together with thermal movement, had resulted in the sand and cement bedding mortar becoming detached from the concrete floor beam. Any further movement within the brickwork, and/or erosion/deterioration of the pointing mortar, could un-lock the brick slips allowing them to become dislodged and fall. Present-day practice is to mechanically fix all brick slips.

The Structural Repair Solution

Action Wall Ties have considerable experience in remediating brick slip defects and have developed methods and equipment to enable the successful fixing of brick slips in situ, avoiding damaging (i.e. cracking with impact hammer type drills) the delicate brick slips. With specially sharpened drills, developed to enable rotary drilling of the slips to complete the fixing, we inserted a special colour matched epoxy putty into the pre-drilled hole then drove a stainless steel fixing into the epoxy putty to fill hole, providing not only a mechanical fixing but bonding all the elements together. We then made good and sealed the access hole with coloured epoxy putty.

Action Wall Ties have developed a unique approach to fixing brick slip issues on low rise and high rise concrete frame buildings. Using their specialist drilling techniques and carefully designed fixings, AWT can repair brick slip defects in an economical manner that maintains the appearance of the building and minimises disruption.

Kent based AWT provide their expertise to customers in Kent, Essex, Sussex, Surrey & London. To arrange a survey or to discuss your project, please call us on 01227 721 255, email us or fill in the contact form.

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.