Can I easily create a small level place or terrace in my yard?

October 28, 2008 4:14 PM

How do I easily grade / level / terrace a small portion of my yard?

We keep our trash and recycling bins on the side of the house, which is on a steep-ish slope. What is the best way to level a small portion of the yard to house these? Bonus points for beginner solutions; I am no landscape engineer and unfortunately we can not afford to hire in. I don't want to risk life and limb on icy trash nights.

posted by Morrigan to home & garden (4 comments total)

I just did this. What you need is a retaining wall.

Go to the local building supply and buy retaining wall blocks. They'll each have a little lip, like the ones picture here.

Basic idea is dig a trench for them, stack em up, and fill behind them with dirt. The blocks have those little lips on them so that when you pile dirt behind them, they lock together.

If your wall is going to be high enough you'll need to also use some kind of cement or other gluing agent. My wall was just basically two blocks high, so I didn't bother.
posted by poppo at 4:36 PM on October 28, 2008

What is steep-ish? Permits are required for retaining walls over certain heights- where I live, it's 36".
posted by oneirodynia at 4:57 PM on October 28, 2008

There are some concerns if you're talking about a steep slope with the retaining wall washing out from below during rain or snowmelt. If you're going to use that idea, I suggest investing in a half-dozen or so 4-foot pieces of rebar to pound through/beneath the bottom row of blocks. Leave them about 6" from flush with the ground, and then backfill as per poppo's suggestion. Bonus points if you make sure there aren't any drains or pipes running through the area -before- you pound them in.

Also, you'll want to tamp down the dirt behind your blocks to keep it from settling and removing support from the blocks. This is about as simple as it sounds; just get something flat and heavy and use it to compact the soil as you put it in. Your feet work perfectly well if you A. make sure the soil isn't bone-dry as you backfill, and B. realize you aren't going to be able to tamp anything thicker than about 6 inches.
posted by Phineas Rhyne at 4:59 PM on October 28, 2008

The blocks poppo describes are called segmental retaining wall blocks -- googling that term will bring up more DIY guides (some from the block manufacturers themselves) than you can shake a stick at. This one has a good diagram about halfway down the page, showing what this kind of wall looks like from the side.

They are heavy (usually 60 to 80 pounds each, depending on the style) but are really easy to work with. Make sure you select a model of block that is designed for the height of wall you need -- a quick check of the manufacturer's website should give you that information. You can have everything you need (blocks, gravel, etc) delivered, so you don't need to transport thousands of pounds of blocks in your sedan.

(There are many other ways to build retaining walls, including timber, stone, poured concrete, and so on, but all of those are usually more trouble than the segmental blocks.)

However, do not do something that will adversely affect the drainage around your house. That means making sure not to change the slope so that water runs towards your foundation, or covering up the french drain that might be helping protect your basement from flooding. If you are at all in doubt, consult a qualified professional.

Have a chat with your local planning department about whether or not you will need a permit, or other issues that may apply. My planning department makes it really clear that it is ok to come in (or phone) and have hypothetical "so, if my friend were to be considering building XYZ" conversations -- they don't use those conversations as a tool to figure out who to go and check up on. YMMV, though I can't see any downside to phoning and asking a bunch of questions. Sometimes the planning and development rules are a real pain in the ass, but mostly they are common sense (such as limiting simple owner-built retaining walls to a safe 36 or 48 inches -- higher than that will usually need an engineered solution, which demands a bit more oversight).
posted by Forktine at 6:33 PM on October 28, 2008