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concrete walkways poured before rough grade? any drainage experts?

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  • Aug 26th, 2021 3:37 pm
[OP]
Sr. Member
Dec 15, 2017
832 posts
937 upvotes

concrete walkways poured before rough grade? any drainage experts?

I moved into a home that is newly built. The city has failed me for rough grade inspection already due to some deficiencies around the lot. The builder has already poured driveway, front walkway and steps. The inspector said the walkway may be too low and require special grading like a retaining wall at the edge of the property. Rough grade contractor has not provided as-built elevations on the walkway and drive way, city inspector commented probably because they know it's going to fail and trying to sneak it by.

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The bottom of wood at the fence is close to design grade and a fill of 7" whereas my driveway and walkway are below that by several inches.

The rest of the neighbours are all getting their side entrance walks poured and we're getting a discount (this is all on our own, seperate from the builder). The concrete contractor wants to take the walkway to the 2nd landing which is about 2-3" above FG at the property line. I think the eventual resolution will end up being a retaining wall at the fence.

Now I'm worried that I'm putting the cart before the horse by pouring this concrete. The strange issue is design shows survey stake shows fill 0.18m at the property line. But adjacent to the property line is public walkway done by the developer and also low. I could be wrong but at this point it is sodded and I don't think the developer is going back there to raise it. Should I call off the concrete pour?
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3 replies
Deal Addict
Jun 26, 2019
1993 posts
1723 upvotes
GTA
First things first, you need to get the subdivision grading plan and the plot plans for your lot. Based on this you know what's proposed and can design accordingly.

The walkway should not cause any issues except for if it is poured low. If its at FG or above FG, it shouldn't cause any issues.

With the walkway being 2-3" above the FG at the property line, I again fail to see the issue. A 3:1 slope can grade out this difference in 9" or a 2% min slope would mean it can be up to 150" away. The better question for this, is how is the drainage supposed to work? Do you sheet drain to your neighbours lot? Is there a property line swale? or is your drainage self contained on your lot?

So in summary, its only an issue if its too low or screws up drainage in some way. Your landscaped area has to be minimum 2% in most cases and swale depths are usually required to be 6" or 0.15m. If you can take the lowest/farthest point on your walkway, and drain it at 2% grade to where it should leave the property, you are likely fine.

What does the plot plan show, and how low is the walkway vs the FG?
Deal Addict
Jun 26, 2019
1993 posts
1723 upvotes
GTA
I should also point out, that in a brand new subdivision you're building a concrete walkway on limited base, on what looks like fill, ie not native, adjacent to a new house.

It's going to settle and settle more closer to your house.
[OP]
Sr. Member
Dec 15, 2017
832 posts
937 upvotes
SubjectivelyObjective wrote: First things first, you need to get the subdivision grading plan and the plot plans for your lot. Based on this you know what's proposed and can design accordingly.

The walkway should not cause any issues except for if it is poured low. If its at FG or above FG, it shouldn't cause any issues.

With the walkway being 2-3" above the FG at the property line, I again fail to see the issue. A 3:1 slope can grade out this difference in 9" or a 2% min slope would mean it can be up to 150" away. The better question for this, is how is the drainage supposed to work? Do you sheet drain to your neighbours lot? Is there a property line swale? or is your drainage self contained on your lot?

So in summary, its only an issue if its too low or screws up drainage in some way. Your landscaped area has to be minimum 2% in most cases and swale depths are usually required to be 6" or 0.15m. If you can take the lowest/farthest point on your walkway, and drain it at 2% grade to where it should leave the property, you are likely fine.

What does the plot plan show, and how low is the walkway vs the FG?
This is an ongoing battle with the builder who is refusing to send me the plot plan or communicate with me. The reason the city failed the rough grade on the first inspection is that the civil contractor didn't as-built any elevations of concrete. I have no idea what the design is anywhere besides the single stake leftover. My property is adjacent to a public walkway and at that stake it is low 0.18m on both sides.


yes its going on non native fill, the contractor has installed steel brackets to the foundation to support the walkway.
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