Historic dockyard Chatham The Smithery – long 3500mm diamond drill for and installing grout ties and Cintec ties
The Smithery at The Historic Dockyard Chatham, a Scheduled Ancient Monument and Grade II* listed building.
The Smithery, built in 1808 and the last building within the walls of The Historic Dockyard Chatham on the English Heritage ‘at risk’ register has been saved.
This important historic building fell out of use in 1974 and is in a very poor condition, funding has enabled emergency stabilisation works to commence.
Action Wall Ties diamond drilled a pattern of 50mm diameter holes horizontally, 3500mm in depth through mass brickwork, prepared for the supply of Cintec sock anchors M16 x 3500mm anchors and inflated in accordance with the specification and manufacturers recommendations by certified operatives.
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.
Substantial cracking brickwork to 18th Century water tower due to corroded mild steel – reinforce, remove corroding steelwork and make good
This building is an interesting 18th century purpose built water tower constructed to service a country estate with running water.
Problem: Cracking brickwork
AWT was contacted by the owners of the water tower with concerns about significant cracking to the brickwork.
On inspection we noted that there was indeed substantial cracking and distortion to the external brickwork, together with corresponding internal cracking.
The cracking noted appears to originate from the embedded mild steel.
Causation
The cracking noted was found to be progressive, mainly due to expanding corrosion from the mild steel RSJ’s lifting and cracking the brickwork and stone work, together with a combination of ageing, seasonal moisture, thermal expansion and contraction (i.e. hygrothermal).
Corrosion of the embedded mild steel resulted in the formation of ferrous oxide that expanded to several times the thickness of the metal it had resulted from, thus breaking out the brickwork and causing lifting and bowing of the walls.
Structural repair solution
Our proposed remedial scheme was to provide a viable repair by firstly removing the corroding mild steel, thus addressing the causation, and thereafter introducing bed joint reinforcement beaming, crack stitching, and lateral restraints to reconnect and restrain the brickwork, together with brickwork repairs to reinstate the uniformity of the wall and apply dry seal.
Starting at the top level and repeating to the lower levels we provided working platforms to accommodate the proposed works, installing temporary support with AWT developed props to brace the steel beams and allow for the removal of the embedded mild steel channels and RSJ’s, together with the removal of the surrounding brickwork.
We then replaced the removed channel with suitable bricks.
Once the brickwork was set the horizontal bed joint between the rebuilt and original brickwork was dry packed providing a supporting connection.
To maintain lateral restraining we drilled the masonry for, and resin bonded, stainless steel 12mm grip bars together with brickwork repairs.
To reconnect the brickwork we installed rows of twin 8mm stainless steel corded joint reinforcement, forming a deep masonry beam to stitch localised cracks and to add cohesion and tensile strength to the brickwork.
Large ornate Victorian square stone and brick bay window failing and rotating – stabilizing, realignment, reinforced and make good
The subject building was a substantial traditionally built semi-detached Victorian residence.
On our inspection we found a scaffold in place and it was apparent that a recent attempt at remedial works had been aborted with temporary timber props and packers left in place.
The handsomely designed front elevation and bay window structure, consisted of a ground floor cant bay of brickwork columns, arches with stone corbels, and supporting columns to each external corner supporting a two-storey square bay window of stone column brickwork with stone quoins above.
To the ground, first and second floors, signs of distortion spreading of the 13½ inch brickwork arches with stone quoins to the front and right side cracking the supported brickwork spandrels above were noted. What appears to be a recently installed bed joint reinforcement and resin injected into the open bed joints was also noted.
Discussion
The movement to this complicated bay window structure was believed to be progressive due to ineffective, inadequate, restraining which has allowed the brick arch to spread drop and the brickwork above to drop and crack, resulting in the stone columns leaning outwards and becoming unstable.
Structural repair solution
Although we can make no comment about the suitability/efficiency of either the design or works undertaken as part of the aborted scheme, the first stage of the remedial works that we undertook was to provide temporary support by deploying AWT designed and developed realigning cramping equipment to realign the masonry elements closing the open joints. Thereafter, we used Action Wall Ties’ specially designed diamond drilling jigs to drill the full width of the bay, through all the different elements, and install stainless steel cords locking the bay together adding tensile strength and forming composite beams together with lateral restraints, finally making good.
As indicated with red double dotted lines on our proposal 1, we introduced twin 8mm stainless steel corded joint reinforcement to form a deep masonry beam.
As indicated with green parallel lines on our proposal 1, to form the beam and reconnect the bay window elevational brickwork and stone quoins, we diamond drilled a 20mm hole through each elevation and installed a grouted 8mm helical bar.
As indicated with green stars on our proposal 1, to reconnect the head of the bay windows to the main elevational brickwork, we diamond drilled a 20mm hole through the side of the bays into the main elevational wall and installed a grouted 8mm helical bar.
As indicated with yellow stars in a circle on our proposal 1, in conjunction with the temporary supporting we drilled a 12mm hole counter bore to 20mm, and screwed directly into floor joists 8mm stainless steel lateral restraints and, with a thick stainless steel washer and nut, applied pressure to assist in realigning the masonry. Once completed this was resin bonded to the masonry.
To the second floor cracked capita, we drilled for, and resin bonded, new 6mm stainless steel remedial ties, making good to disturbed areas only with coloured sand and cement mixture.
Making Good Pointing
To cracked brick arches scheduled for reinforcement listed above, we raked out the existing cracked mortar and repaired 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 works to be sympathetic with the existing by attempting to match replacement bricks, pointing style and mortar mixture for texture and colour.
This Grade II listed mansion in London W1 is now a national museum housing the Wallace Collection. AWT were called in to repair cracked brickwork in the courtyard walls. The brickwork repairs on this heritage building needed to provide a cost effective, long term solution while preserving the appearance of the red brick and render walls.
The subject building in central London, known as Hertford House, dates from the 1770s and features red brick and render courtyard walls.
As part of a major refurbishment cracking to the front courtyard walls was to be addressed.
Working with the main contractor and architects we proposed and completed remedial works including bed joint reinforcement, brickwork repairs and render finish repairs.
AWT used their specialist structural repair techniques to restore structural integrity without the need for visible fixings or slow, costly rebuilding work. The beauty of the red brick and render finish was preserved.
Action Wall Ties are structural repair contractors with the specialist skills required for listed buildings. AWT work along with architects, project managers and local authorities to preserve historic buildings.
AWT are available for large and small projects in London, Kent, 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.
One of London’s King’s Cross station’s main entrance brick arches was sagging and losing structural integrity. AWT was contracted by Network Rail to drill for and install Cintec sock anchors to repair the structural defect.
The subject building was central London’s King’s Cross station. This Grade I listed building’s eastern large spanning brickwork entrance arch was found to be de-bonding.
Action Wall Ties was contracted to drill for, and install, Cintec cementitious grouted sock anchors to reconnect the brickwork.
This entailed drilling 75mm holes into the 225mm arched timber frame and drilling into the brickwork with a 38mm diamond drill vertically to a depth of 1200mm. We then prepared for, supplied and installed cementitious grouted sock anchors with grade 304 stainless steel M12 threaded bar washer and nut.
Action Wall Ties (AWT) are experienced structural repair contractors with the capacity to work on both large and small public sector and infrastructure projects. We can assist with a wide range of structural repairs including the installation of Cintec cementitious grouted sock anchors.
AWT are available for contracts in London, Kent, Essex, Surrey and Sussex. Please contact us via our contact form, by email or call 01227 721 255.
AWT were the chosen contractors for the Crossrail project at the Victorian Connaught Tunnel in central London. Strengthening, pinning and pressure grouting techniques were used for this vital infrastructure project.
The Crossrail project was to breathe new life into the old Connaught Tunnel. It was built by the Victorians but was, at the time of this work, a disused brick-arched structure lying beneath London’s Royal Docks that survived a hit from a bomb during WW2. This was to be the only existing tunnel to be re-used for Crossrail. Works involved the widening, deepening, as well as strengthening, of the existing structure.
Action Wall Ties’ expertise and experience was sought to undertake the proposed strengthening works to the brickwork arches to the approach cutting, and the damaged area of brickwork rings that form the tunnel. This was to be carried out with the introduction of injected grout, grouted ties and pressure grouting areas where the brick work rings had separated, which was believed to be due to bomb damage.
In line with the Crossrail specification to reconnect the brickwork with the temporary supports in place we firstly drilled vertically 20mm holes 1000mm deep and injected cementitious grout, filling any contiguous voids. Once this was set we revisited the grout filled holes and re-drilled to 25mm for, and injected, cementitious grout and 16mm stainless steel bars simultaneously pinning the brickwork rings together.
After the completion of the pinning, in an attempt to fill any voids to complete the reconnection, we drilled a pattern of 16mm holes with the entrance counter drilled to receive injection packers, ready for the pressure grouting injection. With the pre-batched TamCrete MFC grout mixed and holes flushed with water we injected the grout up to 1 bar over injection pressure, until either hydraulic lock or venting grout from adjacent holes is attained.
Finally, AWT made good the entrance holes with concrete repair mortar.
AWT can provide cost effective structural repairs for a wide range of public sector and infrastructure projects. We operate not only in London but across the whole of the South East of England. We have many years of experience working on large projects, liaising with structural engineers and local authorities.
Contact AWT today to book a survey with one of our experienced team of structural repair specialists. Contact us on 01227 721 255, or email us.
