Masonry Reinforcement Systems

CONCRETEREPAIRASSOCIATION

MASONRY REINFORCEMENT SYSTEMS

bersche-rolt.co.uk

[email protected]

01825 713000

Masonry Reinforcement

The advantages of using masonry reinforcement have been known to engineers for many years, but it was not until the early 1990s that corrosion resistant stainless steels were used on a large scale to repair and strengthen damaged masonry structures.

Masonry has excellent compressive qualities and the majority of buildings constructed using this material last for many years with little maintenance.

However, masonry has no significant tensile strength and differential movement caused by substrata changes, moisture or thermal effects usually causes cracking followed by general deterioration of the structure.

Thermal Cracking Between Window Openings

The Principle

Prior to the introduction of masonry reinforcement partial underpinning was often used, but this can result in further damage caused by differential movement between the original foundation and the underpinned section.

The introduction of reinforcing steel to a masonry panel provides that panel with an ability to resist tensile forces however generated.

The Bersche-Rolt system of reinforcement is widely used throughout the UK and it is based on the principle of reinforcing the walls from the outside to form composite masonry beams that spread the imposed loads evenly throughout the structure, which then moves as a single unit. Masonry reinforcement costs less than underpinning, and shows considerable cost savings when compared with pile and raft schemes.

The Design

The design is prepared after the cause of the defects has been established, and any remedial works to drains, trees, etc. has been carried out.

High tensile stainless steel reinforcing bars are bonded centrally into holes or grooves cut horizontally or vertically in the walls.

The reinforcing bars vary in diameter and length but all have a solid cross section with a ribbed surface and spacers to give superior bond and tensile performance.

The design may allow for forming masonry beams for the full perimeter of the building or for local stiffening and restraint of damaged areas.

Work Carried Out by In-house Site Teams

Advantages of Bersche-Rolt Reinforcement

• Significant cost and time savings

• Minimal disruption to building occupants

• Appearance of brickwork unaltered

• High tensile Grade 304 stainless steel reinforcing bars

• Various bar diameters with a greater cross-sectional area

• Bars cut to continuous lengths for full building perimeter applications

• Excellent grout coverage and bond with masonry

• Free of charge site surveys

• Design service and technical support by in-house Structural Engineer

• Only installed by in-house Approved Installers

• Ten or twenty year insurance backed guarantees

• Independently tested by The University of Bradford

Bersche-Rolt Masonry Reinforcement

Outer Leaf

Reinforcement is usually installed in horizontal grooves cut into the masonry of the outer leaf by removing bed joint mortar. In this way stitching may be carried out to stiffen damaged masonry or short beams formed to provide lintel support above windows.

If excessive ground movement has caused damage to the foundations then masonry reinforcement may be used to form ring beams above ground floor windows and above and below D.P.C. level which will act to spread the load away from the weakened area.

After the reinforcement has been installed and cracks filled, all the affected area is pointed in gauged mortar to match the existing finish leaving the appearance of the building virtually unaltered.

Joints Cut Out Ready for Reinforcement to Form Masonry Beam

Reinforcement Installed and Joints Pointed to Match

Inner Leaf

In cases of foundation movement it is often necessary to reinforce the inner leaf which supports the floor and roof weight.

This can be carried out from outside the building by first reinforcing the outer leaf and, after a suitable mortar curing period, cutting below the new reinforced masonry beam in a planned sequence to install reinforcement in the inner leaf.

This technique allows the internal leaf to be reinforced while the building is occupied.

Installing Reinforcement in the Inner Leaf of a Cavity Wall

Associated Works

Masonry reinforcement is one part of the overall remedial design package and the use of ties between the inner and outer leaves, joist restraint ties, straps to prevent roof spread and the formation of movement joints may also be necessary.

In addition to masonry reinforcement Bersche-Rolt have a proven track record in completing:

• Structural Repairs

• Concrete Repairs

• Underpinning

• Mini-piling

• Structural Investigations

• Bridge Repairs

• External Wall Insulation

Forming Masonry Beams Instead of Underpinning

Lintel Reinforcement

Many of the first houses constructed with cavity or collar walls did not have a lintel in the outer leaf and the brickwork was supported by the load bearing window frame.

Masonry reinforcement is often installed to form a lintel before non-load bearing uPVC windows are installed. This method of forming lintels costs less than installing conventional lintels.

It is also used on solid walls with defective timber lintels, to install cavity trays or where rotating boot lintels have resulted in cracking and damage to the brickwork over the windows.

Stretcher Course Before Lintel Installation

Lintel Design

The reinforcement design will vary according to the configuration of the brickwork, whether there is a cavity tray, the presence of air bricks, pipes and tile drip details, etc.

Calculations are provided for the lintel designwhich can be adapted to support the brickwork over windows under the eaves.

By using drilling and grouting techniques the system is readily adapted to deal with various forms of construction and above window brickwork details.

Lintel Installation

To form a lintel over a window the mortar is removed from the first horizontal bed joint above the window head. Mortar is also removed from selected perpendicular joints below that bed joint.

The beam is formed by injecting Bersche-Rolt cementitous bonding mortar into the grooves and then inserting horizontal stainless steel reinforcement mounted on fixed locating spacers, with vertical reinforcement to provide additional support to the lowest course.

The bonding mortar completely fills the grooves and is then compacted to remove voids and to form a 10-15 mm recess for final pointing in gauged mortar coloured to match the existing finish.

Completed Lintel Installation to Same Stretcher Course

Panel & Rig for Independent Testing of Bersche-Rolt Lintel

Reinforced Masonry Lintels

Survey and Proposals

Before it is possible to repair a structure it is essential that the cause of the problem is properly diagnosed. This may involve a period of monitoring by our Structural Engineer to assess the degree of movement.

Although many forms of damage have similar symptoms, each project is different and Bersche-Rolt will either carry out a full diagnostic survey or advise your own Engineer or Surveyor.

Detailed proposals can then be prepared and these will include all the necessary drawings, calculations, specifications and prices.

Each design is covered by our Professional Indemnity insurance and insurance backed guarantees are available on completed projects.

Structural Repairs & Lintel Installations, High-Rise Flats

Testing

Bersche-Rolt have a joint research and development agreement with the Department of Civil Engineering at The University of Bradford and this is co-ordinated by the company’s Technical Manager.

The remedial lintel system has been independently tested by the University and has been shown to conform to a standard which exceeds the requirements of BS5628: Part 2 for Reinforced Masonry.

Technical Support

The Bersche-Rolt Structural Engineer can provide full technical and design support, including the preparation of detailed specifications, proposals and costs for each project.

Arch Bridge Strengthening

Since 1994 Bersche-Rolt have developed masonry reinforcement techniques that allow the installation of stainless steel below the surface of masonry arch bridges.

The research and development programme has shown that “retro-reinforcement” installed in the direction of the arch span can improve the overall performance of the arch and increase its ultimate load capacity by a significant amount.

For more information about Bersche-Rolt reinforcement systems for masonry arch bridges and parapet walls, please ask for a copy of our Masonry Bridge Reinforcement brochure.

Test Facility at The University of Bradford

Services

Bersche-Rolt offer a complete structural repair service, which provides customers with cost and time savings as well as ensuring long-term solutions to their structural repair problems.

We have the in-house expertise to investigate and diagnose the cause of structural defects and then design specific structural repair solutions which are installed by our site teams.

Contact

If you would like to arrange a free of charge site survey or discuss a project with an engineer please call us on 01825 713000 or contact us through our website.

Investigation and Research & Development

Bersche-Rolt and Matrix Reinforcement Systems are Protected By Patents

East Sussex (Head Office) | London | Birmingham | Wakefield | Cardiff

01825 713000 | [email protected] | bersche-rolt.co.uk