How To Fix a Sinking Driveway Drainage System

A sinking driveway can be more than just an eyesore—it can pose safety risks and potentially damage your vehicles. Fortunately, repairing a sinking driveway, particularly one with a drywell, is a manageable DIY project for many homeowners.

In this guide and accompanying video, This Old House expert Mark McCullough shows a homeowner how to fix a sinking drywell in their driveway, demonstrating key techniques and offering valuable insights along the way.

*Cost information in this article sourced from estimates used by HomeGuide.

Signs You’re Facing a Sinking Driveway

Recognizing the signs of a sinking driveway early on can prevent more severe damage to your property. Look out for the following indicators:

• Cracks are forming, particularly around the recessed area
• Difficulty in driving over certain sections
• Visible depressions in the driveway surface
• Water pooling in specific areas

Understanding all your driveway repair options can help you determine whether you need a simple fix or a more extensive solution for your sinking driveway problems.

Assessing the Situation

Before beginning any repair work, it’s crucial to assess the extent of the problem.

Here’s how to do so:

1. Inspect the entire driveway for signs of sinking or settling
2. Check the grade around the drywell to ensure proper water flow
3. Examine the drywell itself for any visible damage or deterioration
4. Test the drainage capabilities of the drywell

McCullough notes that the drywall is still draining effectively despite its sunken state, which is a positive sign for the repair process. However, it’s essential that the water flows properly into the drywall and does not get trapped elsewhere, which could exacerbate the problem.

For driveways with persistent drainage issues, considering effective drainage solutions like permeable pavers or gravel systems might help prevent future sinking problems.”

In one Ask This Old House project, homeowner Anna described how her dry well drain had been “slowly sinking over time” over six years, eventually dropping deep enough to risk damaging cars entering the garage and creating a tripping hazard for her two small children. The lesson: don’t wait for a sinking drain to become a safety issue. Early assessment—measuring the depth of settling and checking that water still flows properly into the dry well—can help you plan a manageable repair before the problem worsens.

When assessing a sinking driveway drain, look for two common culprits. As explained on Ask This Old House, “When I see a hole like this, I think of two things. Number one, there was a tree that was here. They cut the tree off and left the stump behind—over time that rots and everything just goes down. The other thing is sometimes they put in big rocks for a base and they leave a lot of space between the rocks and these fines can wash down into the stone and when they do everything settled and that creates a hole.” Understanding the root cause will determine the best repair approach.

Preparing for the Repair of a Sinking Driveway

Proper preparation is fundamental to a successful drywell repair. Gather the following tools and materials:

• Asphalt patch
• Bricks
• Chipping hammer
• Crushed stone
• Garden hose and nozzle
• Masonry chisels
• Masonry trowel
• Mortar mix
• Mortar tub
• Safety glasses
• Small mason’s float
• String line

Once you’ve cleared the damaged area, don’t skip compacting the subbase before rebuilding. As demonstrated on a This Old House driveway repair, the key is to work in thin layers: “The key to a good base is compaction. So I’m only putting in one bag at a time and compacting that down and then building up in lifts.” Make sure you have a hand tamper on your tools list—proper compaction at every stage is what prevents the repair from sinking again.

Step-By-Step Driveway Drainage System Repair Process

Remove the Grate and Debris

The first step is to remove the grate from the drain.

1. Clear out all debris, including leaves, dirt, and sediment.
2. Inspect the interior of the drywell for any obvious issues.

This initial step is crucial for understanding the depth and nature of the problem. Removing debris clears the workspace and allows you to see any hidden damage that might need addressing.

Expose the Frame

To access the underlying structure:

1. Put on safety glasses.
2. Use a chipping hammer and masonry chisel to remove the asphalt around the grate frame carefully.
3. Remove approximately 6 inches of asphalt surrounding the drain.
4. Once the lip of the frame is exposed, carefully lift it out of the hole.

Exposing the frame can be labor-intensive, but taking the time to do this step properly ensures you won’t miss any critical issues.

Inspect and Clean

After exposing the frame, take the following inspection and cleaning steps:

1. Remove any loose asphalt and dirt with a masonry trowel.
2. Take out any broken or deteriorated bricks.
3. Thoroughly clean the exposed area, using a garden hose to rinse away the remaining debris.

A clean workspace is essential for the repair’s longevity. Thorough cleaning allows for better adherence to new materials and ensures that no old, damaged parts compromise its integrity.

Rebuild the Grate Setting

Now, it’s time to rebuild the structure. Here’s how:

1. Mix the mortar according to the manufacturer’s instructions.
2. Lay a bed of mortar over the existing bricks.
3. Set new bricks into the mortar, tapping them down with the butt of the masonry trowel.
4. Ensure you stagger the joints between bricks and maintain a consistent height.
5. Apply mortar to the inside, outside, and top of the bricks for added strength.

Using proper brick setting techniques is critical when rebuilding the grate structure, as it ensures long-term stability and prevents future sinking issues.

Proper mortar mixing and brick placement are crucial for the new structure’s stability. Follow the manufacturer’s instructions closely and check your work frequently for consistency.

When mixing mortar, aim for what masons call an “oatmeal type consistency”—not too wet, not too dry. As you lay each brick, spread a bed joint and create what’s called a furrow by dragging your trowel through the center of the mortar, which helps spread it evenly under the brick. Apply mortar to the head joint (the vertical joint at the end of each brick), then push the brick into position, working it back and forth so it seats down and in properly.

Pro Tip: Before laying new brick, dampen it first. As one This Old House expert demonstrates: “I wanna spray the brick down just a little bit so it won’t be dry because a dry brick will suck the water out of our new mortar causing it to crack.” A small piece of plywood, known as a mortar board, makes it easier to load and work with mortar right at the job site rather than working from a wheelbarrow or bucket.

Reinstall the Grate Frame

Now it’s time to position the grate frame.

Take these steps:

1. Place the grate frame on top of the new brick setting.
2. Use a string line stretched across the hole to ensure proper height.
3. Aim for approximately 2 inches of space between the top of the frame and the string line.
4. This spacing allows for adequate drainage without creating a depression that is too deep.

Ensuring the correct height for the grate frame helps maintain an even driveway surface and promotes proper water drainage, prolonging your repair’s lifespan.

Securing and Finishing

Follow these final steps to complete the repair:

1. Apply a bed of mortar around the outside of the grate frame to anchor it.
2. Pour crushed stone around the outside of the ring and tamp it down.
3. Fill the area around the grate ring with an asphalt patch.
4. Use a mason’s float to press and tamp the asphalt into place.
5. Smooth the asphalt, tapering it towards the drain.
6. Replace the grate.

Confirm that the asphalt patch blends smoothly with the surrounding driveway to create a seamless finish. Proper tamping and smoothing are essential for a professional-looking and durable repair.

Aftercare and Maintenance of Your Driveway

Proper aftercare is essential for the longevity of your repair:

• Allow the repaired area to set for about two weeks before driving over it.
• Inspect the repaired area periodically for any signs of settling or damage.
• Regularly clean the drywell grate to prevent debris accumulation.
• Seal the entire driveway to protect the repair and improve the overall appearance.

Consider implementing broader landscape drainage techniques around your driveway to prevent water from pooling and causing future damage to your repaired drywell.

Regular maintenance activities, such as cleaning and sealing, are small efforts that can result in significant long-term benefits for your driveway.

Preventing Future Drainage Issues

To avoid future driveway sinking:

• Ensure proper grading around your driveway to direct water away from the structure.
• Obtain professional inspections every few years to catch potential problems early.
• Regularly maintain your driveway, addressing small cracks or issues promptly.
• Use quality materials designed to withstand local weather conditions.

For properties with persistent drainage problems, installing a channel drain installation can help direct water away from trouble spots and prevent future drywell issues.”

Preventive measures can save you considerable time and money by mitigating the risk of future repairs. Often, a little proactive care goes a long way.

When to Call a Professional To Repair Your Sinking Driveway

While many drywell repairs can be DIY projects, some situations—such as those listed below—may require professional help:

• Drainage problems that extend beyond the drywell itself
• Extensive settling or sinking across large areas of the driveway
• Lack of confidence in performing the repair safely and effectively
• Signs of significant structural issues beneath the driveway

For complex drainage issues affecting the entire property, consulting professionals about effective stormwater management solutions may be necessary to address the root causes of driveway sinking.

We strongly recommend hiring a licensed and reputable contractor for extensive or complex issues. If you’re unsure about any part of the repair process, don’t hesitate to seek expert advice.

Our Conclusion

By following the steps outlined and taking proper precautions, you can restore your driveway’s functionality and prevent future issues. Remember to assess the situation carefully and don’t hesitate to call a professional for more complex problems.

Resources

McCullough raised a drywell in a driveway that sunk below grade. After using a chipping hammer and chisel to break away the sunken asphalt, McCullough removed the grate and added gravel. He used EZ Street ready-to-use asphalt and ProMasonry Type S Mortar mix to level out the drywell.

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