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Installing Crack Stitching and Bow Ties

May 10, 2018

Case study

Project Description

Works – Installing Crack Stitching and Bow Ties to specifications provided in the Structural Engineer’s report

Client – London Council Property

The appearance of cracks to the flank wall and separation between the flank wall and a first-floor internal wall prompted a call for a structural survey by Frankham Consultancy Group.

Initial External Observations

A vertical fracture was evident to the flank wall which extends approximately 2 metres down the wall from just below the sill of the window located close to the winders near the top of the staircase providing access from the hallway to the first-floor landing.

At the top of the wall fracture and just below the window sill, bricks are seen to have been laterally displaced adjacent to each side of the fracture.

The external crack width varies in the range of 2mm to 5mm.

Actions Proposed and Undertaken by Premier Contractors

Premier Contractors has many years’ experience of this type of issue and identified that a treatment of Crack Stitching was needed to ensure an effective and permanent repair.

Crack Stitching is a quick, simple method of effecting lasting repair to cracked brickwork. It is also extremely successful when used to reinforce and strengthen brickwork.

Our repair systems use steel bars connected across cracks in mortar to reconnect and stabilise brickwork.

The Process

Stage 1

Premier first used a cutter machine to cut slots into the horizontal mortar beds, extending 1.5 metres either side of the crack, as specified in the Structural Engineer’s report. A video showing the work can be viewed <here>.

Stage 2

Next, the slots were cleaned to ensure a clean cut for installation of the 6-diameter bar

Stage 3

Using a Helfix CS Pointing Gun Kit, Premier injected Heli-bond to the back of the slot and bedded the bar into the Heli-bond.

It is crucial to ensure the bar is covered, and extra bonding is applied.

Stage 4

Finally, BowTie HD was installed to the flank wall into 3no joist. This is a process for which Premier has extensive experience and was as specified in the Structural Engineer’s report.

A video showing the process can be seen <here>.


The property is a residential three-bedroom end of terrace house. Building construction is of solid brickwork external walls, solid internal walls, suspended timber floors and a duo pitch roof of cut timber construction with a tiled covering. The building was likely constructed circa 1930s. The west facing side boundary fence is 3.3 metres from the flank wall of the property and a further 1.5 metres from four trees located on the bank of Pymmes Brook.

May 10th, 2018