Home & Garden

Retaining wall cost to remedy backyard slope?

  • Last Updated:
  • May 31st, 2019 4:05 pm
[OP]
Jr. Member
Aug 21, 2017
195 posts
132 upvotes

Retaining wall cost to remedy backyard slope?

There's a 33% grading slope in my backyard, which takes nearly half of the yard space. :(

I'm trying to get a rough idea of how much it costs and what's invovled to build a retaining wall and level the ground surface. Below are some measurements - the red color fenced L shape area in picture 3 is the slope from top-down, and picture 1&2 are the side profiles (sorry they're in metric and pic 3 is imperial).

Any suggestions? Thanks!
Images
  • profile 1.jpg
  • profile 2.jpg
  • profile 3.jpg
14 replies
Deal Fanatic
Jan 25, 2007
9617 posts
5016 upvotes
Paris
That would be a great way to flood your basement. Water should run away from the house and thats why the lawn is graded this way.
Deal Fanatic
User avatar
Oct 15, 2007
5154 posts
2575 upvotes
20k
Everything has been said before, but since nobody listens we have to keep going back and beginning all over again. - Andre Gide
Deal Expert
May 30, 2005
44937 posts
5514 upvotes
Richmond Hill
Jerico wrote: That would be a great way to flood your basement. Water should run away from the house and thats why the lawn is graded this way.
OP probably meant to level it relatively flat and not completely flat. You don’t need a 33% grading to prevent flooding.
Artisan woodworker crafting live edge tables, end grain cutting boards, and other home decor
Silver Coins | Philips Wake-Up Light with Radio | Heatware
Deal Fanatic
User avatar
Oct 19, 2008
6580 posts
2142 upvotes
GTA
Jon Lai wrote: OP probably meant to level it relatively flat and not completely flat. You don’t need a 33% grading to prevent flooding.
Looks like the 33% is the swale and most of the yard is graded 4-5%
Deal Addict
Jan 21, 2018
4324 posts
4377 upvotes
Vancouver
In our city there is a flood-plain regulation that for all new home construction, the ground floor must be above the level of the crown of the nearest road. This is supposedly to allow the city drainage system to work properly and prevent home flooding.

Most contractors are solving this by dumping in fill to raise the level of the property to the required height. If space is tight they may have to build a retaining wall around the property to do this, but I'm sure they would just leave a slope if they have the space to get away with it. Maybe this is the case with the OP's property.

Unfortunately this regulation was not well thought out, because many roads were already raised a meter above the surrounding land when they were originally built to assist in water runoff and snow clearing. So now in theory the regulation calls for the entire city to be raised by one meter via landfill one property at a time. In the meantime areas of new infill home construction are dotted with houses sitting in one-meter-high trays raising them above the level of surrounding houses and causing flooding on those properties.
[OP]
Jr. Member
Aug 21, 2017
195 posts
132 upvotes
Thanks for your input. I think my case is different though, because there're surrounding properties on the North, West and East. The road is on the South.

The house itself would be sitting on a higher ground than the other properties already (except the ones on the West towards the hilltop).
[OP]
Jr. Member
Aug 21, 2017
195 posts
132 upvotes
I'm now thinking about maybe asking the builder to change the grading so that the slope concaves towards the house.

In this way, I can build a deck to "cover up" most of the slope. Not sure how this impacts water drainage though.
Deal Expert
Feb 7, 2017
15436 posts
12640 upvotes
Eastern Ontario
fiddlewin wrote: I'm now thinking about maybe asking the builder to change the grading so that the slope concaves towards the house.

In this way, I can build a deck to "cover up" most of the slope. Not sure how this impacts water drainage though.
Concave
Toward the house ...

Never gonna happen
The slope has to go AWAY from the house, so the water runs off / away from your foundation
So slope will run highest to lowest front to back
(Most common ... and if in a subdivision, usually done cuz the back of the lot has an easement for drainage / storm sewar)

Occasionally, the slope will run side to side...
but it’s rare
Cuz usually a property has close neighbours / houses ... where your run off would just be affecting their home’s foundation

Honestly, you cannot eff around too much with the slope / grade on your property
It’s designed this way for a reason
And cuz it is a flood hazard the municipality is going to uphold that design
(It’s designed like this for the whole of a subdivision / municipality ... to compensate for all the non organic surfaces that happen in a community ... drainage is a serious matter ... so it’s not just your house, it relates to a far greater whole)
[OP]
Jr. Member
Aug 21, 2017
195 posts
132 upvotes
By "concave" I mean looking from top-down. It's just the "L" in the plot would be folded along the diagonal of the yard.

In this way, the house would still be on the high spot with the slope decling away from it. It's just the slope would be moved closer to the base, and will be covered by a future deck - similar to a look-out yard.
Deal Expert
May 30, 2005
44937 posts
5514 upvotes
Richmond Hill
fiddlewin wrote: By "concave" I mean looking from top-down. It's just the "L" in the plot would be folded along the diagonal of the yard.

In this way, the house would still be on the high spot with the slope decling away from it. It's just the slope would be moved closer to the base, and will be covered by a future deck - similar to a look-out yard.
I assume you mean you want it to look like this

----|
----\
------____________

Instead of

----___
----_______\
----________|
Artisan woodworker crafting live edge tables, end grain cutting boards, and other home decor
Silver Coins | Philips Wake-Up Light with Radio | Heatware
Deal Fanatic
User avatar
Oct 19, 2008
6580 posts
2142 upvotes
GTA
Jon Lai wrote: I assume you mean you want it to look like this

----|
----\
------____________

Instead of

----___
----_______\
----________|
When water fills his neighbours basement he can go like this:

¯\_(ツ)_/¯
[OP]
Jr. Member
Aug 21, 2017
195 posts
132 upvotes
Water will flow to the neighbouring properties anyway since they're lower.
Deal Addict
User avatar
Feb 10, 2010
1382 posts
733 upvotes
Toronto
Just an idea, since the road is on the south side maybe a horseshoe grading will work? so the water run on the sides of the house and to the road (sewers).
[OP]
Jr. Member
Aug 21, 2017
195 posts
132 upvotes
There would be other properties on the West and East. West property is higher - so basically this house is on the "corner" of a small hill, which creates this "L" shape. :(

Top