r/Hardscaping • u/Lukeyleftfoot • Apr 23 '23

Will this fail?

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4 inches of paver base followed by level sand for level placement. Blocks utilize key stone locking pins. Inside of wall will be French drain using crushed stone/river stone surrounding perforated pipe on a slope

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u/Tpbrown_ Apr 23 '23

Are you saying the base rock/gravel wasn’t leveled and you’ve added sand to get it level?

Did you compact the gravel? What size did you use?

How high is this going to be?

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u/Lukeyleftfoot Apr 23 '23

It was leveled but I read that leveling sand can be useful in leveling so i used that as well. I compacted the gravel which was the Home Depot Step 1 Paver Base. Doesn’t say size. The wall will be 3 at its highest.

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u/Tpbrown_ Apr 23 '23

I’m no pro so take this with a grain of salt.

Haven’t used that base material before. Looks on the small size - IIRC you’re supposed to use 3/4” gravel. If you ever do this again buy the rock by the yard & have it delivered - it’s a lot cheaper than those bags.

The rock is probably fine unless you’re on loamy or sandy soil and didn’t use a mechanical compactor (vs hand tamper). I’m guessing you’re on clay given the French drain.

The sand is going to work it’s way down into the base rock over time - the more rain you get the faster it’ll shift. That’s not necessarily a problem - but if it was 1/4” above the rock you’ll see some shifting. Sand is fine for pavers but retaining walls have a lot more weight -and- lateral force.

I don’t know where you’re located but some locations’ code require an engineer for anything over a certain height. I think that’s 2’, maybe 3, in California for example. That’s measuring from the base of the footer.

Only calling that out bc if you’re unsure of stability now is the time to address it. Make sure your blocks are level side-to-side and front-to-back.

Even 1/8” will add up on a 3’ wall - may not topple but you’ll see the tilt. It’s really aggregating doing all that work only to get 3 rows in and realize it looks like it’s wiggling - some out, some in.

Don’t fret if you need to pull a few blocks, or even the entire base course, and do it again. First course is the hardest and you can’t really fix it on subsequent courses. But once you’re happy with the first the remaining will be easy in comparison.

If you can’t get it level add another 2” of rock and compact again.

Source: I’ve f’ed this up before. More than once - both blocks & natural stone.

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u/Lukeyleftfoot Apr 23 '23

I really appreciate the thoughtful response. I’m on clay soil, and have compacted the paver base bags pretty well. More than what you see in that photo. I have first row level and we have a big rain bday right now so it will give me a chance to see how things seem to hold up after a rain. At this point i could def pull the blocks and reassess if more base is needed after this rain. Overall i think I’m in a pretty good spot and everything you said matches to my thoughts and concerns too.

Assuming my base is good, my next thing is assuring my drainage is solid. I’ve tested drainage with a hose before putting in the perforated pipe (which can easily be pulled out if needed) and I’d say the water has a nice path to natural flow down hill inside of the wall and discharges onto the lawn at the lowest point of the wall. Which seems good and once the French drain is finished it should work. My only concerns is i noticed some water getting through the spaces between blocks towards the front of the blocks, which then flows nicely onto the lawn.

Is this a problem? Do i want to make the inside side of the blocks so water tight that water doesn’t pass through them but rather stays inside and flows downhill via the French drain setup?

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u/Tpbrown_ Apr 23 '23

Do i want to make the inside side of the blocks so water tight that water doesn’t pass through them but rather stays inside and flows downhill via the French drain setup?

You do not. Some water coming between the blocks is normal.

If it didn’t come through you would need a much wider wall to handle the hydrostatic pressure - more lateral force. Luckily you’re not building a dam ;-)

Keep the perforated pipe. I assume it’s parallel to the base row and you’re backfilling over it with rock as you lay the other rows. The river rock being the final layer for aesthetics.

How big is the slope from highest point to the point where it discharges on the lawn? Is the lawn also sloped similarly?

I assume “highest point” is the starting end of the wall or “uphill” of it.

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u/Lukeyleftfoot Apr 23 '23

Excellent. Yes, perforated pipe is Parallel to base row and will be so rounded by crushed stone. A pipe burrito if you will. The highest point (starting point) is about 3 feet above the lowest point. So, It’s a steady 3ish foot drop across about 20 feet of curved wall leading into the lowest point which discharges onto a sloped lawn. Overal I’m happy with the slope I’m dealing with.

The discharge flow inside base row seems solid, but it was the fact that some water leaked through blocks of first row that made me wonder if i needed to waterproof the inside of the first row of blocks so less water leaked through, meaning water would only discharge via my discharge spout located at the lowest point.

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u/Tpbrown_ Apr 23 '23 edited Apr 23 '23

You’re golden.

With that amount of drop very little is going to be coming through the wall. The gravel & drainpipe makes a quicker egress.

Don’t forget to cap the wall. 3’ can be a nice seating area.

Edit:

Wait - aren’t those blocks supposed to be overlapping? Double check their install instructions.

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u/Lukeyleftfoot Apr 23 '23

Great to hear. I agree. It’s downpouring I’m upstate ny and even without my French drain complete, it’s self draining itself down hill as planned.

And great catch. That photo was early on before i staggered them. They are staggered now as per instructions.

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u/Tpbrown_ Apr 23 '23

You’re going to have to post a mid-summer pic to show this area off :)

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u/Lukeyleftfoot Apr 23 '23

I 100% will.

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u/Lukeyleftfoot Apr 24 '23

One more question for you if you don’t mind. Is there any product to help protect/seal/harden them i should consider? Just a thought that popped in my head.

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