Your porch's concrete steps take a lot of abuse over time from foot traffic and the elements. Eventually, the concrete can crack, crumble or fall apart, becoming a tripping or slipping hazard.
Assess and Prepare
Carefully examine the structural shape your steps are in. Depending on the kind of damage there is, you may have to do various types of repairs. In most cases, damage goes deeper than what the eyes can see on the surface. First and foremost, you'll need to prepare the surface of the steps. Use a hammer and mason's chisel to chip away at any soft or crumbling concrete in and around the cracks or crumbling areas. Chip Away Soft or Crumbling Concrete with a Hammer. Clean the surface with a stiff brush to remove all loose particles. You can also try an air compressor or a can of compressed air to blow out particles and dust. Rinse the steps well, making sure the surface is damp, but free of any standing water.
Use gloves, goggles and a dust mask when preparing the steps or handling cement products.
Don't use a wire brush when cleaning off your steps. Any broken bits of wire left behind can cause rust stains on your steps.
With the concrete prepared, now it's time to repair the damage. Depending on the shape your steps are in, you may need to do one of the following tasks. See below.
Patch Small Cracks
Step 1: Apply Bonding Compound (Optional)
If you have thin hairline cracks, you can usually use a vinyl patching compound to fix concrete stairs. Most Vinyl patch products contain a bonding agent, but if yours does not, apply a bonding compound to the surface prior to patching. This will create the best bond possible between the old surface and the patching material. Use an old or inexpensive paintbrush to work the liquid into the surface. Wash the brush immediately after use with soap and water or discard it.
The primer will stain so avoid getting it on any adjacent surfaces. Wash it off promptly if it does get on any other surfaces.
Step 2: Apply Patching Compound
Depending on the size of the crack, use a putty knife or a trowel to apply a vinyl patching compound in multiple layers, as directed by the manufacturer. Mix only the amount of patching you'll need for each layer. Press it firmly to force the initial layer into all nooks and crannies and allow drying time between layers. Vinyl patch will repair most surface damage of 3/8” or less and will span stable hairline cracks up to ¼”.
You can also patch thin cracks with a cement mixture. In a small bucket, mix one part cement and three parts sand with enough water to make a stiff paste. In a separate container, mix a small amount of cement with more water— enough to make a cement "paint."
If you can, ''paint'' the inside of the crack with the thinner cement mixture. This will act like a primer. Then take the paste mixture and pack it firmly into the crack with a putty knife or trowel. Level the mixture with a straight-edged concrete-finishing trowel. Let the patch sit undisturbed for about an hour, then go over the entire surface with a float or trowel in a circular motion, blending it well with the surrounding surface.
When applying the patch, make sure you cut deeply into the mixture with your trowel to remove any air pockets.
Repair Large Cracks
Step 1: Prepare the Crack
Simple patching is for simple cracks. If the cracks in your steps are deep (more than 1/4'' wide and 1/2'' deep), use foam backer rods. Sold in a variety of lengths and diameters, foam backer rods are great for supporting crack sealant and preventing it from sinking into any cracks as it dries and ages. Use a putty knife to force the flexible rod into the crack, placing it about 1/4'' below the surface. An alternative to backer rod is using fine dried sand swept into the prepared crack to a level ¼” below the surface.
Step 2: Apply Crack Sealant
Once the foam backer rods are in place, follow Step 2 under Patching Small Cracks to apply the patching compound. After smoothing the patch with a trowel, let it set for a couple of hours. Then cover it with a sheet of plastic, weighing the plastic down at the edges with bricks or rocks. Keep the area covered for an entire week, making sure to give it a little water each day to keep it moist.
When making a patch repair using a vinyl patch, its best to dampen the surface prior to application to prevent premature drying. When applying a crack seal, work on a dry surface and avoid rain or excessive moisture on either repair for 24 hours,
If you don't have the time to completely repair a crack in your stairs, try a stop-gap repair solution. Simply pack the crack with sand and seal it with waterproof tape. This type of repair will hold for the short term until you have enough time to properly repair the crack.
Repair Broken and Crumbling Cement
Step 1: Build a Form
You may have to build a form to repair missing corners and edges of the stairs. These forms hold the patching material in place while it hardens. Measure the height of the step you are repairing and use a board that's as long and as tall as the damaged step — a 2" x 6" board will work in most cases. Place the board lengthwise against the vertical face of the damaged step, and stack several bricks against it at each end, holding the board firmly in place. Additional forms may be needed for an outer corner. Brace the side boards as needed to form the outer edges. You can strengthen the formed corner by screwing the boards together using a power drill and some wood screws. For best results, the top edge of the form should be level with the flat surface of the step.
Remember that your form doesn't need to be built to last long-term. Be sure it can be easily taken apart after your repair has set. To avoid disturbing the patch as you remove the form, remove any screws or braces/weights. Then carefully slide the form as you lift it away from the step.
Step 2: Apply the Patch
Depending on the depth of the damage, you will need to use either sand mix (up to 2” thick) or a standard concrete mix (over 2”) to make the repair.. Apply a liquid concrete bonding agent to the surface of the damaged concrete with a small, stiff paintbrush. Use either the sand mix or concrete mix as directed by the manufacturer. Using a trowel, press the initial material firmly into the space between the existing surface and the wood form to assure a good bond and fill the broken area completely.
Step 3: Texture the Repair
When the patch has set, but before it has dried (time varies according to the mix and weather conditions), texture the area you repaired so it matches the surrounding area. After removing the form, use a block of wood or a float to smooth the surface. Use a swirling motion to level the patch and blend it into the surrounding area. If the surrounding area is a rougher texture, use a stiff brush or broom in a similar manner. For a smooth finish, use a steel trowel. Use an edging tool to round over the corners to match the existing shape.
Step 4: Slow Cure the Patch
Cover the patch with plastic to slow down evaporation. This is also known as slow curing. This process prevents the patch from cracking. Dampen the surface a couple of times a day and recover with plastic for the next two to three days.
Congratulations! Your concrete steps look like new again.
Project Shopping List
Here’s what you’ll need to complete this project successfully.
- Mason's chisel
- Stiff brush
- Air compressor
- Can of compressed air
- Garden hose
- Dust mask
- Concrete bonding adhesive or primer/additive
- Old paintbrush
- Putty knife
- Vinyl patching compound
- Polyurethane or Latex based self-leveling crack seal
- Caulking gun
- Cement mix
- Float (optional)
- Straight-edged concrete-finishing trowel
- Foam backer rod
- Plastic sheeting
- Bricks or rocks (to hold the plastic in place)
- Wood (2" x 6")
- Bricks or concrete blocks
- Power drill
- Wood screws (optional)
- Sand mix
- Concrete mix
- Stiff brush
- Edging tool