How to Repair Cracks Caused by Inadequate Wall-Tie Bolts?

How to Repair Cracks Caused by Inadequate Wall-Tie Bolts

Repairing such cracks requires addressing the root cause(inadequate ties)first—fixing cracks alone will fail as unstable walls redevelop stress.Follow this structured process:

1.Diagnose&Resolve the Tie Bolt Issue

First,hire a structural engineer to assess tie inadequacy(e.g.,missing ties,incorrect spacing,corrosion).Replace or add ties per code:

For cavity walls:Install new stainless-steel or galvanized ties(match original type)using drill-and-anchor methods,ensuring proper spacing(typically 450–600mm vertically,900mm horizontally).

For solid walls:Use helical or resin-fixed ties to bind separating layers,verifying load capacity with the engineer.

2.Prepare the Crack for Repair

Clean the crack:Remove loose mortar,dust,or debris with a wire brush and compressed air.For wide cracks(>5mm),chisel a 10–15mm“V-groove”along the crack to improve filler adhesion.

Dry the area:Use a fan or dehumidifier to eliminate moisture—dampness reduces filler effectiveness and risks future mold.

3.Fill the Crack by Size

Narrow cracks(<3mm):Use masonry crack sealant(acrylic or polyurethane-based).Apply with a caulking gun,smoothing excess with a trowel.

Medium/wide cracks(3–15mm):Use mortar mix(matching original mortar color/strength)or hydraulic cement.Pack the filler into the groove,ensuring no air gaps,then tool to match surrounding joints.

Large gaps(>15mm):Insert metal lath or fiberglass mesh into the crack first for reinforcement,then fill with mortar in layers(allow each layer to dry 24 hours).

4.Finish&Protect

Once the filler dries(24–48 hours),sand rough edges and repaint/stain to match the wall.Finally,check wall drainage(e.g.,clean gutters,add weep holes)to prevent moisture-related tie damage and crack recurrence.