Patch a chipped concrete step
Rebuild a small missing edge on a stable step with a compatible repair mortar.
Home · 2–3 hr + cure · Medium
Before you start
Block access to the stairs. Wear eye protection, suitable gloves and dust control/respiratory protection for the material. Wet cement can burn skin. Avoid power grinding and stop if the step is unstable or damage extends into reinforcement.
Tools and materials
- Vertical/edge-rated repair mortar and its specified bonding additive or primer
- Stiff brush, small cold chisel and hammer if needed, trowels, mixing tub, measuring container, gloves and eye protection
Check the problem
Confirm this is a local chip
Inspect the whole step for rocking, deep cracks, rust staining or loose handrail fixings. A patch restores an edge; it does not make a failing stair structurally sound.
Choose a repair system
Measure chip depth and select mortar approved for vertical edges and that thickness. Read its minimum thickness, substrate preparation, bonding and curing instructions; generic concrete mix is not automatically suitable.
Steps
Isolate and remove loose material
Close the route to foot traffic. Remove only unsound fragments with controlled hand tools, stopping at firm concrete. Follow the repair product’s edge-shape requirements without enlarging sound damage unnecessarily.
Clean the repair area
Brush and collect debris, then remove dirt or contaminants by the product’s approved method. Prepare the required dampness or dryness; leave no standing water.
Prepare a small batch
Measure the specified water or additive exactly. Mix only what can be placed within working time. Do not retemper stiffening mortar by adding extra water.
Pack and rebuild the corner
Apply the specified bonding treatment if required. Press mortar firmly into the recess, eliminating voids, and build only to the permitted layer thickness. Support with a temporary form if the product requires it.
Shape to the existing step
When the mortar reaches the product’s finishing stage, reproduce the original edge and tread profile. Keep the repaired tread flush and match a slip-resistant finish; do not create a hump or change the riser height.
Protect, cure and inspect
Maintain the prescribed curing conditions and keep traffic off for the full stated period. Check the patch is bonded, firm and flush with no cracks or loose edges before reopening the steps.
Maintain the prescribed curing conditions and keep traffic off for the full stated period. Check the patch is bonded, firm and flush with no cracks or loose edges before reopening the steps.
Tips
Stage tools first
Fast-setting mortar can become unworkable before a second trip to the shed.
Keep the tread safe
A smooth glossy patch can be slippery; match the surrounding texture.
Watch for recurrence
A patch that separates again can signal moisture, movement or unsound concrete below.