Crack Stitching Case Study

The Crack Stitching Case Study

The summer of 2018 has been the hottest summer that we have endured since 2006, with temperatures averaging 25°C – 27°C you would think that we were in a tropical country! The weather may have been ideal for a nice bbq down by the river or a few casual drinks in the garden with friends but unbeknownst to you, the weather has been less ideal for your property.

The Issue

This years heatwave caused serious problems for the UK’s landscape, what was once green turned yellow and dried up, not because of the level of heat but the absence of water. The average fully grown tree consumes round about 200 gallons of water a day, in simpler terms that’s a whopping 757 litres! With trees and plants fighting for the little moisture they can get, the dryer the earth becomes creating a potential threat of subsidence to your property.


Subsidence is the act of the foundations of your house being pulled further into the earth’s surface because the land that your property’s been build on has dried out. Unfortunately, this happens at different speeds in different patches causing the land to stretch and or shrink at different rates which pulls or pushes your property unevenly leaving you with some nasty surprises E.g. Doors tighten in their frames, cracks appearing on the interior or exterior of your house and worst case scenario  your house falls down!

The Fix

Like many things we don’t have control over we can never stop the earth’s surface shifting. The only thing that we can do is correct the problems and strengthen the foundations of our property, this can be achieved through a series of methods such as:

  • Crack Stitching
  • Mass Concrete
  • Beam and Base Underpinning
  • Mini-Piled Underpinning
  • Resin Injection

In this Blog post we will be focusing on Crack Stitching and why we chose to use this process to help strengthen a lovely little house in the Dachet area that was effected by subsidence due to this years heatwave.  


This cute little cottage was unexpectedly hit by a case of subsidence, Luckily the owners of the property had spotted the issue and contacted us immediately to voiced their concerns. The same day we managed to get one of our Structural Engineers out to the property to view the issue and what we found was that the cottage had suffered minor movement causing the newly built extension to pull away from the house. This is shown in the images below.
By looking at that wall you can’t really see much wrong with it correct? Catching subsidence issues early is vital for your properties structural health that’s where our Structural Engineers come in. We sent Andy Walker over to the property and he will point out all the issues that you should look out for with your property.
As you can see from where Andy is pointing to, there is a crack running through the join connecting the side extension to the house.
The crack runs the length of the wall and is visibly wider at the top of the join which indicates that the extension is being pulled away from the house.
As you can see in the image above cracks have appeared on the house wall which could end up threatening the properties foundational integrity
The red arrows in the image above point to the cracks that run close to a concrete support beam and also an air vent which are both vital points in the wall.
Once all the cracks had been analysed it was time to start addressing the problem. The structural repairs team was called out and briefed on the situation.
After being briefed our Structural Repairs team member got his PPE on and started the crack stitching process.
The process starts with making cuts in between the bricks so that crack stitching rods can be inserted into the wall to help improve the structural regidity
The cuts were then inspected to make sure they were the right depth and also that they were clean, the cuts being clean is an important factor in the next stages.
We then prepped our crack stitching kit.

  1. Thor Helical W60 Flexi Grout
  2. Grout Gun
  3. Thor Helical Twisted Rods
  4. Pointing Tool
The flexi grout was then mixed to the correct consistency for maximum effectiveness.
Flexi grout was then put into the grout gun and carefully put into the cuts made in the wall.
The twisted reinforced crack stitching rods were then inserted into the cuts that have the flexi grout in.
Once the bars had been placed within the cuts filled with flexi grout and left to dry it was time to mix up some cement to fill in the cuts.
Using the pointing tool our Structural Repairs team member filled in the remaining space within the cracks with the cement to seal in the stregthening rods and flexi grout.
The above image is the end of the crack stitching process, as you can see it looks good as new! All the cracks have been regrouted and the strengthening rods that are now safely hidden away within the walls help strengthen the wall. The Thor Helical twisted strengthening rods have a TEN YEAR guarantee on them so you’ll be covered if anything goes wrong with them although that is very unlikely. If you have noticed cracks appearing in your walls it’s better to be on the safe side and give us a call so we can come and get an inspection started. For anymore information feel free to contact us at any time. We’re based around London and the surrounding areas. We look forward to hearing from you.

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