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How To Guide: Crack Stitching
How to do Crack Stitching
A step by step guide to repairing vertical or stepped cracks in masonry walls. Repairs carried out using this system will stabilise the structure, provide resistance against further cracking and restore the structural integrity of the masonry. Repairs using this system are made quickly with the minimum of disruption, are inexpensive and cause no further damage to the wall.
Before attempting to repair a crack in a wall we suggest a structural engineer is consulted to determine the cause of the crack and how the masonry repair strategy should be undertaken.
1. Cut a slot in the mortar bed just over 500mm either side of the vertical crack and to the correct depth, dependent on the wall thickness (see below). Ensure the mortar is completely removed to reveal the top and bottom faces of the masonry. Remove all loose material using a blow out pump and then flush the joint with water. Normally vertical spacing is every 4 - 6 brick courses but check with a structural engineer if in doubt.
2. Mix the Perma Cem Anchor Grout thoroughly using the paddle mixer provided and load into the gun. Pump the grout to the back of the slot in a continuous even bead to approximately two thirds of the slot depth.
3. Push the helical bar firmly into the grout, making sure that the bar extends 500mm either side of the crack.
4. Apply a second bead of grout into the slot making sure that the bar is completely covered and with the trowel provided force the grout into the slot until it is approximately 10mm from the surface and ensuring that the bar and grout are firmly packed.
5. Finish by making good the bed joint and filling the vertical crack with an appropriate filler to match.
Notes: If two or more cracks are close together then bars can be lapped ensuring that the bar extends 500mm either side of the outer cracks and that the laps are at least 500mm. Helical Spiral bars should be bent and bonded at least 100mm around corners when cracks are within 500mm of the corner or a reveal etc. This system can be used for rendered or plastered walls.
It is important before carrying out the installation of this system that the cause of the cracking is established and remedied and a structural engineer consulted if necessary.
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