Block Retaining Wall Question

[dartsportsteve]

Guys - I'm attempting to build a short retaining wall along the east side of my sloped driveway. The plan is/was to have the rows of block level and step them up as the elevation increased. I had not thought about how they would leave a gap between the concrete driveway and each stepped new row of block, since they have the lip that catches the back of the row just below.

My question is with that gap. I can just fill it with pea rock or decorative rock and be done with it, but I'm wondering if that is what the pros would do? I've also thought about setting the first row of block directly on the concrete, letting the wall slope at the same degree as the driveway, but I'd run into issues 4' from the garage where I have less of an incline.

I'm leaning toward continuing the way I've been doing it, but just filling the gap as I go with decorative rock. And no, I don't want to dig down far enough to have one continuous bottom row at the same level...


Here are a few pics:

 

[wnstwolf]

I would bury one more course of blocks under that even with the drive level. Would just make a nicer look and may even keep out the weeds..
Great work on the driveway by the way. Nice finished product..

 

[dartsportsteve]

I would bury one more course of blocks under that even with the drive level. Would just make a nicer look and may even keep out the weeds..
Great work on the driveway by the way. Nice finished product..

I had thought about that, but I'll still have a gap between the concrete and the second row. My budget is already pretty well busted, too so I'm trying to get by without buying any more block.

Thanks for the complement! I'm pretty proud of my work so far.

 

[wnstwolf]

Think you need to dig deep and bite the bullet on more block. Something with that much effort and eye appeal needs to be done right the first time..

 

[GirlnAgarage]

I'm not understanding how you want to use pea gravel on the driveway side of the blocks. How many courses are you going up? How do you expect little rocks (the most annoying type of rock btw imo) to pile up and stay on that little ledge of each brick?

Lay the bricks and be done. The slight offset of each should add aesthetics.

 

[buening]

A full block should always be buried when installing landscape block retaining walls. A bed of compacted pea gravel should be used as a base, otherwise the dirt beneath a block will erode and you will have settlement under certain blocks (this will make it look pretty bad). The only way to eliminate the block stepping backwards is to use a block that doesn't utilize the lip, which often uses rods in a pocket at the back of the block (or use split face CMU/cinder blocks). Short of returning the block and getting a different type, there isn't a way of eliminating the setback of the courses. Its only going to get worse as you get closer to the garage

 

[dartsportsteve]

I'm not understanding how you want to use pea gravel on the driveway side of the blocks. How many courses are you going up? How do you expect little rocks (the most annoying type of rock btw imo) to pile up and stay on that little ledge of each brick?

Lay the bricks and be done. The slight offset of each should add aesthetics.

There should only be three courses. The space that I'm talking about filling is the space where you see gravel between the concrete and the wall block in the first picture. The pea gravel wouldn't sit on top of the blocks, it would fill that gap.

 

[dartsportsteve]

A full block should always be buried when installing landscape block retaining walls. A bed of compacted pea gravel should be used as a base, otherwise the dirt beneath a block will erode and you will have settlement under certain blocks (this will make it look pretty bad). The only way to eliminate the block stepping backwards is to use a block that doesn't utilize the lip, which often uses rods in a pocket at the back of the block (or use split face CMU/cinder blocks). Short of returning the block and getting a different type, there isn't a way of eliminating the setback of the courses. Its only going to get worse as you get closer to the garage

I'm using compacted road gravel as a base, so I shouldn't need to worry about settlement. So the only right way to do it is to run the first course of blocks all the way from the start of the wall to the edge of the garage, then step the subsequent courses, correct?

I hadn't thought about it until now either, but the gap due to the offset of the blocks will also translate into a gap at the garage wall. I'll have to do something there too.

I'm beginning to think I should have just done poured concrete for this wall. I'm no landscaper.

 

[GirlnAgarage]

There should only be three courses. The space that I'm talking about filling is the space where you see gravel between the concrete and the wall block in the first picture. The pea gravel wouldn't sit on top of the blocks, it would fill that gap.

Ohhh I looked at it again and think I got it now, the circled part right? Sorry 'bout that


I think like buening said you'll need to step the bottom row. Do it the entire length of the driveway. Sure, will take a little more work and time to ensure it is level, but that will eliminate that gap problem. Remember the quality of the work is often in the details

 

[buening]

Looking at your pics closer, it appears the last block in the bottom course of your block in the first picture is fully buried. Pea gravel could be used to fill the gap between blocks and driveway, just make it thick enough to keep weeds from growing. It appears you will have at least three lays/step ups of block based on your driveway slope. This means you will have three times the gap at the garage than what you will at the sidewalk. Something to think about

 

[GirlnAgarage]

I'm using compacted road gravel as a base, so I shouldn't need to worry about settlement. So the only right way to do it is to run the first course of blocks all the way from the start of the wall to the edge of the garage, then step the subsequent courses, correct?

I hadn't thought about it until now either, but the gap due to the offset of the blocks will also translate into a gap at the garage wall. I'll have to do something there too.

I'm beginning to think I should have just done poured concrete for this wall. I'm no landscaper.

Can you make a 90* at the end when you get up to the garage wall? You'll still have the gap but that corner will angle back and it'll seal the end.

 

[dartsportsteve]

Looking at your pics closer, it appears the last block in the bottom course of your block in the first picture is fully buried. Pea gravel could be used to fill the gap between blocks and driveway, just make it thick enough to keep weeds from growing. It appears you will have at least three lays/step ups of block based on your driveway slope. This means you will have three times the gap at the garage than what you will at the sidewalk. Something to think about

Yup! That was the plan that I had mentioned. I just must not have described it very well.

I just realized though that I'll have to run a perpendicular wall at the garage to fill the gap at the top of the wall there. I'll get it figured out. Thanks!

 

[dartsportsteve]

Can you make a 90* at the end when you get up to the garage wall? You'll still have the gap but that corner will angle back and it'll seal the end.

I think that's what I'll have to do.

 

[enrare]

I think the only way to avoid the gap you are dealing with is to use a different block that dosn't have the built-in set-back shoulder.

 

[MoonRise]

Looks like insufficient base prep and depth (looks like you are putting the lowest blocks right on 'dirt' and not on a sufficient depth of properly compacted base material such as 'crusher run' or 3/4 mix gravel), not burying the blocks deep enough at the step-up transitions (the lower block is supposed to be fully buried and then the next 'upper' course sits on top of that), and seems like the 'wrong' block for that severe of a side slope.

http://www.allanblock.com/retainingwalls/Installation/Landscape/stepups/stepup.aspx?ta=1

http://www.allanblock.com/retaining...e/FieldstoneStepUps.aspx?ta=3&Fieldstone=True

By the time you lay block up near the house, I think you would be looking at a step-back gap caused from the side-slope around 4 inches or so. Which IMHO is going to look like ****.

IF you are set on using that block with the lip, I think you have to knock the lip off of the 'underground' blocks and then use mortar or a masonry construction adhesive to hold the lower blocks in place and set the blocks so that your blocks up near the house
line up with the front edge even with the edge of the concrete driveway.

http://www.keystonewalls.com/pages/products/GardenWall.html?tab=3#Landscape_tabs

Or go with a 'pinned' type of block and set the blocks in the 'front' position with esentially no step-back between courses. Or do the mortar or adhesive between courses and no step-back using either your existing block with the lip knocked off or another stackable no-lip block.

http://www.dannylipford.com/how-to-build-a-stackable-block-retaining-wall/

 

[dartsportsteve]

Looks like insufficient base prep and depth (looks like you are putting the lowest blocks right on 'dirt' and not on a sufficient depth of properly compacted base material such as 'crusher run' or 3/4 mix gravel), not burying the blocks deep enough at the step-up transitions (the lower block is supposed to be fully buried and then the next 'upper' course sits on top of that), and seems like the 'wrong' block for that severe of a side slope.

http://www.allanblock.com/retainingwalls/Installation/Landscape/stepups/stepup.aspx?ta=1

http://www.allanblock.com/retaining...e/FieldstoneStepUps.aspx?ta=3&Fieldstone=True

By the time you lay block up near the house, I think you would be looking at a step-back gap caused from the side-slope around 4 inches or so. Which IMHO is going to look like ****.

IF you are set on using that block with the lip, I think you have to knock the lip off of the 'underground' blocks and then use mortar or a masonry construction adhesive to hold the lower blocks in place and set the blocks so that your blocks up near the house
line up with the front edge even with the edge of the concrete driveway.

http://www.keystonewalls.com/pages/products/GardenWall.html?tab=3#Landscape_tabs

Or go with a 'pinned' type of block and set the blocks in the 'front' position with esentially no step-back between courses. Or do the mortar or adhesive between courses and no step-back using either your existing block with the lip knocked off or another stackable no-lip block.

http://www.dannylipford.com/how-to-build-a-stackable-block-retaining-wall/

I have 4-5 inches of compacted 3/4 road gravel under the first course. The first course is buried to the point that the bottom of the next course will be below the level of the concrete driveway where the "step" is. Compacted gravel under the next level, up to level with the first course.

Why would this block not work for this slope? I understand the gap/offset issue with the lips, but why would there be an issue with the slope? It will only be holding back 18-21" of backfill.

 

[dartsportsteve]

I think I understand what you're saying; because of the slope and the number of stepped courses, the gap is greater at the top of the wall near the garage foundation wall. This is what we'd talked about a couple posts earlier, that there will be the need for a set of perpendicular blocks at the top of the driveway next to the garage to compensate for the gap. The longer runs from the slope could then fill the offset created in the small perpendicular wall.

 

[buening]

Lipped block typically can handle up to 3' of retained earth before issues arise, so I don't see an issue with the block structurally. The setback of the wall actually helps with retaining the soil. Similar to someone trying to push you standing upright verses you leaning against them slightly, harder to push you over when you are leaning in. Knocking the lips off and grouting each section could work but will be a ton of work for you. It would eliminate the setback issue, but you also need to keep in mind you lose the retaining benefits of the setback and will risk the wall trying to tip in (since it doesn't have enough block depth for a good "footing").

 

[dartsportsteve]

Lipped block typically can handle up to 3' of retained earth before issues arise, so I don't see an issue with the block structurally. The setback of the wall actually helps with retaining the soil. Similar to someone trying to push you standing upright verses you leaning against them slightly, harder to push you over when you are leaning in. Knocking the lips off and grouting each section could work but will be a ton of work for you. It would eliminate the setback issue, but you also need to keep in mind you lose the retaining benefits of the setback and will risk the wall trying to tip in (since it doesn't have enough block depth for a good "footing").

Thanks. I think I'll stick with my current plan and fill the gap with decorative rock or pea gravel.

 

[jhelrey]

Retaining wall block steps back 3/4 of an inch every 6 inches. Just part of the game

 

[jhelrey]

Since it is a tiny wall, you could bust the backs off of them and stack then straight up.