Retaining Walls

failing retaining wall

Retaining walls can be constructed from a variety of materials, including landscape stone, fieldstone, ledge rock, brick, poured concrete, concrete blocks, and even railroad ties. These structures are typically designed to support soil on steep or vertical slopes, helping to prevent the land—and potentially your home—from shifting or sliding downhill.

In addition to stabilizing terrain, retaining walls often serve to address drainage and erosion concerns. Regardless of their specific function, retaining walls represent a significant investment and require regular care to ensure their long-term performance and safety. It’s important to periodically inspect your retaining wall for signs of damage such as shifting, displacement, bulging, leaning, or loose materials. If you discover any loose components or cavities that could lead to structural failure, it’s highly recommended that you or a qualified contractor address these issues promptly. Delaying repairs can result in further deterioration and substantially higher costs down the line.

retaining wall fail

If your property features timber retaining walls—such as those made from railroad ties (as pictured above)—it’s important to inspect them regularly for signs of internal damage. Over time, Carpenter Ants and Termites can infest these wooden structures, hollowing them out and significantly weakening their integrity. To check for potential issues, periodically probe the wood for soft or hollow areas, especially if the wall has been in place for several years. If an infestation is detected or suspected, the affected sections may need to be replaced.

If you're planning to replace a wood retaining wall, consider upgrading to more durable materials such as landscape stone, poured concrete or other masonry options. These alternatives offer greater longevity, enhanced structural integrity, and typically require less maintenance over time compared to wood. Remember, a retaining wall lacking proper drainage can result in significant and costly repairs down the line.

Drainage and Erosion Protection for Retaining Walls

Ensure that the lower footings of your retaining wall are well protected from erosion, as this can significantly compromise the structure's integrity. One critical feature to check for is the presence of weep holes—small, exposed openings located at the lower outside portion of the wall. These holes typically contain pipes that penetrate through the wall, allowing water to drain from the soil behind it.

Drainage from behind a wall is essential in preventing water buildup, which can lead to pressure, shifting, and long-term damage to a retaining wall. For larger retaining walls, weep holes are commonly 4 inches in diameter to ensure sufficient drainage. Proper spacing between them allows for even water flow across the wall’s base. In certain situations, perforated drainage pipes, typically encased in geotextile fabric or placed in a gravel filter bed, are used to direct water from deeper sections of the backfill to the weep holes. However, not all retaining walls include weep holes. Some retaining walls have perforated piping placed within the aggregate, which channel water around the structure.

retaining wall drainage

If your retaining wall is solid and no weep holes are visible, I strongly recommend consulting a professional landscaper to confirm that your retaining wall has integrated drainage. The absence of proper drainage can result in serious issues, such as heaving, displacement, or leaning of the wall over time due to water retention. During our freezing winter months, the water that gets trapped behind the wall can freeze as temperatures drop. When water freezes, it expands, which can further increase pressure on the wall and lead to cracking or shifting of the wall structure. Conveying water from behind any retaining wall is crucial.

SEE MY CLIENTS FAILED RETAINING WALLS ON GOOGLE PHOTOS

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Hi Dave,

I want to thank you for the home inspection you did for us at 144 Avis Ave. in Dracut MA. We did not get the house because the home owners did not want to split the cost of fixing that wall. I had gotten two estimates, one from a landscaper and one from a Mason. Both gave an estimate of $15,000.00, for which I am grateful for your inspection and pointing out the wall problem. It would of been an undue burden on us, not to mention I am also grateful about the radon testing also. I just got the results today and they came back at 7.5 and 8.4, so that would of been another expense. I do hope that when we find a new house that you will be able to do our home inspection. Your fee was a drop in the hat, to what it would of cost us to fix the wall and then the cost of venting the basement. My husband was also very impressed with your report and how well it was written. Just wanted to drop you a line to let you know what happened, and hopefully will be doing business with you again very soon.

Have a Good Day
Jackie Sliney