Localised subsidence Archives

Bowing brickwork on Victorian semi

Victorian mid-terrace house rear addition bowing and dropping brickwork – stabilisation, bed joint reinforcement beaming, crack stitching, fenestration lintel repair, grouted tie and lateral restraints

The subject building was a traditionally built Victorian mid-terrace domestic residence, consisting of three floors below a pitched tiled roof.

Problem

Signs of distortion and distress, with localised cracking, were noted to the far external gable wall of the rear addition – along with cracked and dropped brick arches to the first and second floor level. Previous repairs of old tie bars with patress plates, large steel straps, rebuilding and re-pointing were noted, indicating a history of movement.

A significant outward bulge to the side elevation at first floor level with localised cracking was also noted, as was significant downward movement at the rear doorway with all brickwork leaning towards that point.

Causation

The movement noted was attributed to subsidence, which may well be historic as internal redecoration shows no sign of cracking. Under these circumstances we did not consider that underpinning was warranted at this stage. Our pragmatic solution was to reinforce and tie back the building by using a combination of bed joint reinforcement and lateral restraints into the first floor construction to reinstate structural integrity.

Solution

AWT’s remedial scheme was the introduction of bed joint reinforcement beaming, crack stitching, fenestration lintel repair, grout tie injection and lateral restraints – 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.

1. Reinforcement:
We introduced two rows of twin 8mm stainless steel corded joint reinforcement to form a deep masonry beam – as indicated with red double dotted lines on our proposal images.

2. Grout tie injection:
We drilled into the party wall and bent into the hole one of the grouted 8mm stainless steel cords – as indicated with red stars on our proposal images.

3. 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 and passed into the line of the deep masonry beam installed within the existing masonry – as indicated with green parallel lines on our proposal images.

4. Crack stitching:
We stitched localised cracks with the introduction of single 8mm stainless steel corded joint reinforcement – as indicated with red single dotted lines on our proposal images.

5. Lateral restraints:
In conjunction with the beam, we introduced 8mm stainless steel lateral restraints 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.

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

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.

Victorian mid-terrace bay window repair

Victorian mid-terrace house bay window generic repair. Victorian mid-terrace house – Generic subsidence and cracking bay window repair

This building was a traditional two-storey mid-terrace domestic residence of Victorian vintage with a pitched tiled roof.

Problem – cracked bay window

The front bay windows showed visible distortion and distress, accompanied by significant cracking to both the main brickwork and brick entrance arches, which had also dropped.

Causation – subsidence

It was clearly evident that the bay window had rotated away from the main building line, owing to subsidence. The bay window’s foundations were shallow compared with those of the main building. This situation had been exacerbated by the close proximity of a tall tree that was further desiccating the clay subsoil, though the subsidence was not deemed severe enough at the time to warrant underpinning.

Bay window repair Solution

The bay window was tied back to the main elevation using stainless steel bed joint reinforcement. This served also to beam up the brickwork and repair the cracking. In addition, the bay was tied back to the two floors behind to provide proper lateral restraint. The arch was pinned up, using stainless steel pins, and resined into the brickwork above. After installation, pointing was raked out, reinstated and tinted to match the existing (see coloured remedial works on our proposal picture).

Arboricultural works were undertaken on the tree (by others), to reduce the crown and accordingly lower its water demand from the underlying clay.

Read our frequently asked questions about bay window structural repairs.

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

Bungalows with failing lintels and localised subsidence

Kent Bungalows with failing lintels and localised subsidence

Bungalows with failing lintels and localised subsidence – bed joint reinforcement beaming, fenestration lintel repair and crack stitching

This small development comprised detached purpose-designed bungalows and maisonettes for the elderly. Each block was of a similar design, facing a common central garden. To the front elevation of each block there was a central gabled section accommodating a first floor with a single-storey wing on both sides.

Structural Problems

Signs of distortion and distress with cracked and dropped brick arches, both cracking to the brickwork to the ground and first floor windows and cracking to the brickwork below the ground floor windows were noted.

Discussion

We believed that the movement noted was progressive, due to inadequate lintels. The cracking noted below the ground floor window could be attributed to some localised subsidence. The buildings were to undergo a window replacement programme and it was requested that our proposal included the restraining of the single brick arch above each window.

Structural Repair Solution

AWT completed a remedial scheme providing a viable repair by introducing bed joint reinforcement beaming, fenestration lintel repair and crack stitching.

Bed joint reinforcement beaming: The introduction of two rows of twin 8mm stainless steel corded joint reinforcement, forming a deep masonry beam – as indicated with red double dotted lines on our proposal images.

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 deep masonry beam installed within the existing masonry – as indicated with green parallel lines on our proposal images.

Made good the pointing: To the cracking schedule for reinforcement, 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 and around the Canterbury Kent area. Contact us on 01227 721 255, or email us.

Bay window cracking dropping subsidence

Failing Victorian terraced house bay window cracking dropping subsidence – bed joint reinforcement beaming, crack stitching and brickwork repairs

Victorian bay window subsidence repair.

The subject building was a socially-owned Victorian terraced house with significant bay window cracking and rotational movement reported.

Structural engineers had been engaged and their investigation revealed the bay windows’ footing had been affected by leakage from a damaged drain and repairs instigated.

To avoid costly underpinning and new footing, the structural engineers recommended delaying any further works to allow some recovery of the underlying clay to take place.

Thereafter, they recommended that remedial works should be undertaken to include some rebuilding of the rotated brickwork at ground floor and the reconnecting and restraining of the bay window structure at ground and first floor levels with bed joint reinforcement and lateral restraints.

Action Wall Ties designed and completed the remediation works

Our remedial scheme provided a viable repair by introducing bed joint reinforcement beaming, crack stitching and brickwork repairs to reinstate the uniformity of the structure.

To the basement level of the front bay window we provided temporary support and braced the brickwork columns to accommodate the deconstruction of a sufficient amount of distorted brickwork to accommodate the realignment and reconnection of brickwork and masonry elements onto the existing footing.

Action Wall Ties (AWT) are specialists in masonry reinforcement and repair, providing professional solutions to a wide variety of structural problems including Victorian bay window cracks and movement including subsidence and other issues in the South East (around Kent and London). Contact us on 01227 721 255, or email us.