So, what’s the deal with clay?

Leda clay, Ottawa’s Shaky Foundation

Do a quick Google search of “Leda clay” (also known as Quick clay or Champlain Sea clay) and you will learn that it is highly unstable. Unfortunately, this type of soil covers much of the Ottawa area.

Why should you care?

Take a look at the map below and identify where you live. Are you located in one of the salmon colored areas? If you live in Orleans, you are literally sitting in a pool of Leda clay. Constance Bay and parts of Kanata are built on Leda clay and there are pockets of it under the entire city.

Here is a list of questions and answers for you to consider as you read through your estimate.

Q: I notice you have included a POTENTIAL EXTRA COST – Excavation line in our estimate. What’s that about?

A: If you are situated in one of the identified clay “hot spots” in Ottawa, we tend to include this in the estimate. Consider this a “heads up” when budgeting. Depending on what we find when we lift up the current asphalt and dig test holes, we may or may not need to excavate.

Q: If I am located in a known “hot spot”, isn’t it true that I will have to excavate? Why do you even list it as an option?

A: Not necessarily.

Sometimes it is better to not touch the clay (for various reasons). We will make this decision once we have
evaluated the soil.

If you moved into your home after the driveway was initially paved, you may not be aware of the condition of the base. Perhaps, the previous homeowners already had the base dug out.

Q: Other contractors have stopped by and they didn’t mention anything about clay or the potential need for excavation. Why?

A: Many customers choose their contractors solely on the lowest price. Contractors know this. By not putting that potential extra cost line in your estimate, it appears less scary. Customers often look at the final number on our estimate and toss it aside for the cheapest one in the pile without considering this: just because you choose the cheapest estimate NOW, it doesn’t mean that you will come out on top in the END.

So, you need to decide. What scenario seems more appealing to you:

1. We tell you up front so you can budget accordingly. No surprises down the road. Yes, the number may be high right now, but we are preparing you for the worst case scenario.


2. We don’t mention anything about clay or the possibility of excavation. You see the low estimate and hire us. We arrive to pave your driveway and find out that we need to excavate. We ring your doorbell and tell you that, “Oh, by the way, your driveway requires excavation. That will cost you another X
amount of dollars on top of what I already quoted you.” Are you prepared for that? This scenario happens all too often in our industry.


3. We arrive to pave, dig test holes and find clay. We say nothing to you and simply pave over top. We take your money and hope for the best! And you are none the wiser. Again, another scenario that happens all too often in our industry. Digging out clay is not a pleasant experience for contractors and it requires a lot more time and care. When time is money, a lot of contractors just want to get in and out without dealing with the sticky clay and the responsibility of rebuilding a driveway PROPERLY.

So, you decide.

Q: How can you tell if my driveway will require excavation?

A: As soon as the existing layer of asphalt is ripped up, we will dig test holes in various locations and make a decision. Once we have made a decision, WE WILL DISCUSS THIS WITH YOU BEFORE WE PROCEED.

Q: How will I know if you are telling me the truth about the presence of clay in my driveway? You could just tell me anything and I won’t know any better.

A: You know more than you think!

You should know that we will never just go ahead with excavation without consulting with you first. We will actually take you out into the driveway to show you what we have found. And you will know clay when you see it. We have even had instances where customers have walked on previously soft spots in their driveway and sunk! And don’t be surprised if you feel like you are creating a wave when you walk. That is the clay shifting under your feet!

You can also use the map to help determine the likeliness of the need for excavation. If you are in a “hot spot” go look at your current driveway. Is your driveway littered with cracks? How about sink holes? Look at where your car wheels typically sit. Do you see depressions? What about in front of the garage? Is there a noticeable gap between the asphalt and the garage floor? And what about humps? Does the driveway look wavy? These are all indicators that you may be sitting on clay and that you may require excavation.

Believe me when I tell you that we would RATHER NOT touch clay. It is a messy, time consuming job. Once it is determined that you require excavation, we know that your job will most likely take twice as long to do (forcing us to redo our schedule) and our machinery will now be coated in muck. Everything slooooooowwwwwws down at this point. The clean up is often horrendous. So, if we are telling you that you SHOULD excavate, we really mean it.

Q: If you suggest that we proceed with excavation, do I have to do it?

A: The short answer is “no.” If you think this is your forever home, then we suggest you spend the extra money to properly prepare the base. This will ensure that you are not repaving the driveway prematurely down the road. But maybe you plan to sell the house in a couple of years and you are just looking for the “quick fix” to make it “look pretty” for the time being. In this case, maybe you would opt to not invest in the base. Really, we leave the decision to you. WE WILL NEVER PRESSURE YOU TO EXCAVATE. WE WILL ONLY ADVISE.

Q: I see that you only offer a one-year warranty when clay is present…even if I spend the money to get the base redone. Why is this? Why can’t you give me the two-year warranty?

A: As we’ve said, this type of clay is extremely unstable. Even if we dig down and rebuild your driveway properly, clay surrounds you. There are no guarantees that that clay won’t shift.

You should know that some companies won’t even offer a warranty in areas where clay is present (even if you opt for excavation). There are just too many unknowns to contend with. Clay is known to shift and in the winter there can be more issues with cracks because the clay prevents the water from draining properly. With our freeze / thaw cycles here in Ottawa, this can become a real issue.

Think of it like this: we are paving over a material akin to Jello. Would you warranty this?

Q: If I opt for the excavation option, can you guarantee that I won’t have issues down the road?

A: No. No, we can’t guarantee this and to be quite honest, nor can anyone else. There is only so much that we can control. We do our part by stabilizing the base as much as possible (using proper materials and following proper procedures), but the rest is up to Mother Nature.
Keep in mind that clay can shift. Asphalt can only flex so much.

Q: So, if you suggest that I excavate and I decide not to, what happens?

A: We will do as you please. You should know that at this point, you are saying “no thanks” to the warranty. We WILL NOT warranty your driveway in this case. You are essentially purchasing a sturdy table top with wobbly legs at this point. Sure, it may look strong on the surface, but apply a little pressure and you will see the consequences.

That’s the deal with clay.

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