Leveling a small concrete pad involves identifying uneven areas and applying techniques to create a flat, even surface. Here’s a breakdown of common methods:
1. Assessing the Concrete Pad
Before you begin, thoroughly inspect the concrete pad.
- Identify Low Spots: Use a level (a long one is best) to find areas where the concrete is lower than the surrounding surface. Mark these clearly with chalk or a marker.
- Consider the Cause: Is the pad simply uneven, or is it cracked and damaged? Significant damage might require more extensive repairs or even replacement.
2. Leveling Methods
Several methods can be used, depending on the severity of the unevenness and your budget.
a. Self-Leveling Concrete
This is often the easiest solution for smaller pads, especially if the unevenness isn't too extreme.
- Preparation: Clean the concrete pad thoroughly. Remove any loose debris, dirt, or oil. You may need to etch the concrete surface with muriatic acid (following safety precautions carefully) for better adhesion.
- Priming: Apply a concrete primer specifically designed for self-leveling compounds. This helps the self-leveler bond properly to the existing concrete.
- Mixing: Carefully follow the manufacturer's instructions for mixing the self-leveling compound. Use the correct amount of water and mix thoroughly to avoid lumps.
- Application: Pour the self-leveling compound onto the pad, starting in the deepest low spots. It will spread and level itself. You may need to use a gauge rake or trowel to help it along.
- Curing: Allow the self-leveling compound to cure according to the manufacturer's instructions. Keep it protected from direct sunlight, wind, and rain during this time.
Tips for Self-Leveling Concrete:
- For deeper depressions, consider adding a small amount of pea gravel aggregate to the self-leveling compound, as referenced, to extend the material's coverage and reduce cost, but be sure to check the product's specifications to confirm compatibility.
- Damming can be necessary: if the pad edges are not raised you can apply strips to create a wall.
- Do NOT use self-leveling compound if the concrete is spalling or crumbling, it will not adhere.
b. Using a Sand Mix (For Slight Depressions)
This is a cheaper option for very minor imperfections:
- Clean the area: Thoroughly clean the low spots.
- Apply a bonding adhesive: A concrete bonding adhesive can help the sand mix adhere to the existing concrete.
- Apply the Sand Mix: Mix sand with cement and water to create a workable mortar. Apply this mixture to the low spots, carefully leveling it with a trowel.
- Curing: Keep the area damp for several days to allow the mortar to cure properly.
c. OSB Shims and Self-Leveler (For Larger Depressions)
This method is mentioned in the reference and allows to fill large gaps without wasting too much self-leveler.
- Prepare OSB Shims: Cut OSB (Oriented Strand Board) sheets to fit the low areas.
- Secure Shims: Securely screw the OSB sheets to the concrete pad in the low spots. Ensure the screws are countersunk so they don't protrude above the OSB surface.
- Apply Self-Leveler: Pour self-leveling compound over the OSB sheets, burying them completely. This provides a stable, level base without using excessive amounts of self-leveler.
3. Considerations
- Drainage: Ensure that leveling the pad doesn't negatively impact drainage. You might need to create a slight slope away from buildings.
- Expansion Joints: Be mindful of existing expansion joints in the concrete pad. Avoid covering them entirely with leveling compounds, as this can cause cracking.
- Safety: Always wear appropriate safety gear, including gloves, eye protection, and a dust mask, when working with concrete products.
4. When to Call a Professional
If the concrete pad is severely damaged, cracked, or uneven, it's best to consult with a professional concrete contractor. They can assess the situation and recommend the best course of action, which might involve repairing the existing pad or pouring a new one.
