Westlands Primary School, Sittingbourne

Structural Renovations Helifix

Structural Renovations secured the works to complete concrete repair and masonry stabilisation to Westlands Primary School in Kent, working as a specialist sub-contractor to Kier Construction.

Westlands Primary School was constructed in the 1960’s and is a typical example of many schools built during the period with brick facades, reinforced concrete features such as window cills, window surrounds, columns and flat roofs with overhangs.

The window cills, lintels and surrounds are constructed from reconstituted stone or ‘engineered stone,’ using natural stone aggregates, such as portland, mixed with a cementitious binder, that is intended to resemble natural quarried stone. A recurring issue with this type of construction is that the embedded mild steel reinforcement which is used to provide tensile strength is compromised by both low cover and the relative high porosity of the reconstituted stone. This leads to expansive corrosion of the reinforcement (due to the presence of moisture and oxygen) and causes the ‘stone’ to crack and spall. Entire sections can be damaged by this process and repair is generally the most cost effective and practical method of treatment.

The treatment in this instance was to mechanically remove all loose and defective ‘stone’ together with any reinforcement that had lost significant section. New stainless steel reinforcement was fixed in position using a two part polyester resin. A temporary timber shuttter was formed to the profile of the area to be reinstated, which included drip, upstands and falls. The prepared broken back surface and reinforcement was coated with Sika MonoTop 610 and reinstated with Sika MonoTop 615 back to the original surface profile.

The brickwork in places at Westlands Primary School had diagonal, stepped cracking which required stabilisation. These were reinforced using Helifix Helibars set in Helifix Helibond Grout, a non-shrink cementitious grout, within the bed joints at regular centres along the length of the crack. Once installed the reinforced areas were repointed to match the existing pointing.

The works are to be completed over a number of phases to suit both the major refurbishment scheme by the Principal Contractor as well as the school term times and operating hours.

Royal Hospital Chelsea

Royal Hospital Chelsea

Grade I listed and designed by Sir Christopher Wren, ‘The Royal Hospital’ was founded by King Charles II in 1682 as a retirement and nursing home for soldiers of the British Army.

The hospital is situated close to the River Thames, in the the Royal Borough of Kensington and Chelsea on a 66 acre site. The residents of the hospital are known as ‘Chelsea Pensioners.’

Structural Renovations were employed by Wates Construction to stabilise the chimney breasts within the building, reform feature brickwork dressings around windows and repairs to stonework within a number of the rooms.

The chimney breasts had the timber panelling removed exposing the cracked brickwork beneath. Bed joints at regular centres were ground out, being careful not to damage the 300 year old hand-made bricks. Stainless steel helical bars, set in non-shrink cementitious grout were installed into the pre-soaked slots. The slots were then repointed using a lime mortar.

The deep red brickwork dressings around some window openings had, over time cracked and spalled due to expansive corrosion of metal inclusions and frost damage following moisture ingress. The defective brickwork was removed using only hand tools to avoid further damage.

Stainless steel pins were drilled in to sound substrate and set in a two part polyester. Usually a specially colour matched, modified mortar, the repaired areas were reinstated and whilst still not fully cured the brickwork was carved to the required profiles to include ‘dummy’ perp and bed joints, which were subsequently pointed with another colour-matched mortar.

Stone work repairs were completed using stainless steel pins for support and a colour-matched, modified mortar.

This project was secured with Wates following successful completion of masonry repairs to Somerset House another one of London’s Grade I listed buildings.

Salters Hall, Fore Street

Salters Hall

Salter’s Hall is situated within the City of London, close to London Wall. The Worshipful Company of Salter’s is a livery company first licensed in 1394 to trade in salt and is ranked 9th in order of precedence and therefore one of the ‘Great 12.’

Their original building in St. Swithin’s Lane was bombed during a German air-raid in 1941 and the decision was taken to move to their current location on Fore Street, adjacent to the Barbican in 1976. The building, designed by renowned architect Sir Basil Spence, was listed in 2010 and carried Grade II status. It is built in the brutalist style of architecture.

The entire structure has received a major refurbishment (its first since construction) and has been honoured with a special livery award by the Company of Chartered Architects, in the City Building of the Year 2016.

Structural Renovations secured the first package, which was concerned with significant concrete repair to columns and beams, using Weber.Cem HB40, a high strength polymer modified repair mortar. The package also required us to replicate the ‘knapped’ rib finish and various other profiles. This was achieved using Weber.Cem Lightweight and whilst still ‘green’ the mortar was hand carved to form the required finish.

We returned for a second phase of works in autumn 2015, which involved the installation of replacement reinforcement and re-profiling of concrete elements.

Summer 2016 saw us return to carry out concrete repairs to areas that were not accessible during previous visits. In addition we were instructed to carry out site trials using a lime and silicate based thin coat render, followed by the application of a highly specialised mineral paint system. The site trials were specifically for the new pavilion, which has been built to the east of the building and where the architect required a particularly smooth and uniform finish. The trials were subsequently approved and we returned to site in autumn 2016.

The various phases were undertaken within strict programme periods, involving multiple interested parties that included City of London Corporation, DMFK Architects, Capita, as well as the Salter’s.

Bush House

Bush House

Grade II listed Bush House, which was home to the BBC World Service for over 70 years, was commissioned and designed in 1919, planned as a major new trade centre and designed by American architect Harvey Wiley Corbett.

Built from Portland stone, Bush House was in 1929 declared the “most expensive building in the world,” built at a cost of around £2,000,000.

The building underwent a period of refurbishment and due to the basements current use the works were coordinated effectively to accommodate the tenants as well as meeting the strict programme deadlines.

Due to historic water ingress issues into the basement Structural Renovations successfully tendered and were subsequently employed to carry out repairs to the defective concrete soffits, beams and columns. Repairs were completed using Sika MonoTop 610 and 615 and corrosion control was installed by way of Sika Margel 580 VPI vapour phase inhibitors drilled and fixed into the soffits at regular centres to prevent any latent defects.

Additionally the failed render was removed from two retaining walls and replaced with a new traditional sand and cement render before being over coated with Flexcrete Cementitious Coating 851. This coating acts as a structural waterproof membrane and can resist positive and negative pressure under 100m head in water retaining structures and enhances the durability of reinforced concrete by reinstating effective cover.

The works were completed within budget and programme.


Broadbent Building, Heron Hall Academy

Heron Hall Academy

The Broadbent Building and adjacent gym block on the site of the former Middlesex University campus in Enfield, has undergone a major refurbishment as part of the new Heron Hall Academy project.

The art-deco facade is of a special interest and incorporates, now listed ceramic tiles. The building is constructed from brick with reinforced concrete floor slabs supported by reinforced concrete columns and beams.

Working as a specialist sub-contractor to Willmott Dixon Construction, following successful completion of other recent projects, we have been repairing and coating the external concrete elements which include the window cills, window heads and roof overhang, which project around the full perimeter of the buildings on all facades, as well as the entrance canopies.

The works have been carried out using Flexcrete materials and have included; Monolote hand-placed repair mortar for the repairs the the defective concrete and Monolevel 250F as a fairing coat, which has been specially formulated for application over existing coatings, being applied to all exposed concrete surfaces. To complete the system two coats of Monodex Smooth, a protective anti-carbonation coating primed with Bond-Prime, was applied. The system provided the client with 15 year guarantee.

Whilst on site we were also instructed to carry out internal concrete repairs using Flexcrete Monomix repair mortar, external brick stitching using Helifix Helibars and the installation of new expansion joints.

We are due to return to site in the new year to compete the second phase of the works.

Worth Abbey

The Abbey Church at Worth in West Sussex was built in 1966 and consecrated for worship in 1974. It is has the largest capacity of any church in Sussex seating up to 900 people and the monks gather 6 times daily to pray.

The grade II* listed church was designed by the Architect Frances Pollen and is constructed from insitu concrete with a felt roof. To achieve the large open space he used a bridge building technique never before used in a church.  It is considered by many to be the finest example of 1960s modernist architecture in Britain.

Kier were awarded the year long refurbishment contract and we secured the subcontract to restore both the internal and external concrete.

Whilst our works were carried out, other trades completed lowering of the floor to the choir area, upgrading lighting and sound systems, alterations to M & E, re-roofing and window replacement.

External repairs were carried out to all reinforced concrete, with preparation by dry ice blasting to remove old coatings from the ribbed surfaces and high-pressure water jetting to prepare uncoated smooth surfaces. The prepared concrete was treated using a migrating corrosion inhibitor, followed by the application of a pigmented, elastomeric coating. All products were manufactured by Sika Ltd.

Internally, the reinforced concrete ribs which support the roof above, together with the two chapel areas, were prepared and treated using a micro-porous pigmented coating, providing a uniform finish to otherwise patchy surfaces. Products for this element of the works were manufactured by Keim Mineral Paints Ltd.

The refurbishment of the church was successfully completed in time for reopening on Pentecost Sunday as planned.