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Terracing/redi-rock retaining walls

Posted by marisany (My Page) on
Tue, Mar 29, 11 at 18:23

We are trying to make a quick decision about terracing our yard, which slopes so much that it is unusable. We've wanted to do it for years, but put it off because of cost. We now have an opportunity to do it for a reasonable price by piggybacking on our neighbors' project.

They had their similar yard terraced last fall, and are now putting in a pool. They brought their yard up 12' at the rear using two 6' retaining walls separated by 6' (this part of their yard they have effectively lost). We were talking last fall about having their landscaper give us a quote, but I did not pursue it, assuming that the cost would be too high. Now they are back, digging out the pool, and I finally spoke to the guy. The cost is reasonable, and we are considering it and would like to make a decision by the weekend. They would use as fill some of the dirt dug out for our neighbors' pool (giving us a cost savings).

Our yard slopes so much that the grade difference between our patio next to the house and the lowest point along the rear property line is 16'. Our plan would be to put a 6' (max) retaining wall along the rear property line; the ground is uneven enough that the wall would fade away to nothing behind the garage. We would extend our patio 4-6', and the ground would be cut away, giving us a larger patio with an adjacent 6' retaining wall, and a flatter (1.5' grade to the rear) yard.

The material that the landscaping guy uses is cast concrete blocks (Redi-rock) that fit together like Legos. I have photos below showing the material in our neighbors' yard. I am wondering whether this material would look all right - it is white, although it is supposed to darken over time. It would need to be masked with plants. We would also have steps made out of this material leading from our bluestone patio through the wall to the lower level.

Any opinions/advice would be welcome. I have some photos:

Looking up at house from back of yard. That overgrown bush will go. The pile of dirt is from our neighbors' pool; it will either be used in our project or removed next week. The old stone retaining wall will be buried if we do the project.

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Our neighbors' upper retaining wall at the corner of our property. This is the material we would use. Our existing old retaining wall can be seen:

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Another view of our neighbors' two retaining walls from our yard:

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The rear of our house from halfway down the yard. Our patio would be extended forward 4-6', and the ground cut away so that there would be a 6' retaining wall with steps going through it from the patio to the rest of the yard, 6' below. This wall could be straight or curved.

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View of our neighbors' terracing from our patio:

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View of our garage at the opposite side of the yard from our neighbors. With the new grading, the ground would be fairly level at about 1' below the siding:

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Follow-Up Postings:

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RE: Terracing/redi-rock retaining walls

Two quick questions first: what is down below your lot - are there other houses, or a creek/ravine, or a road? In other words, if your wall fails, what does it fail onto? And similarly, who if anyone will see this wall, other than you when you are down on a lower level?

Second, just to clarify that where you plan to build the wall, you will be covering a portion of the stone foundation of your garage?

KarinL


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RE: Terracing/redi-rock retaining walls

There are much newer houses behind us, fairly small lots, like ours. These houses are very low, we look over their rooftops. They have significant drainage problems (across the street from them is a bit of conservation land and a tidal inlet from the ocean). They are built on slabs and are in a flood plain. My neighbors' wall has already helped the drainage situation for the house behind her. This is the first spring in years (since a new house was built on what had been a vacant lot on the other side of my neighbors) that her backyard has not been flooded. The woman behind me has done some landscaping that is designed to absorb water, to help her flooding problem - a rain garden? If we do this project, it should help. As it is now, the water sheets down our yard onto her property. If the wall should fall, it would fall onto her yard (but why would it fall?). In terms of seeing the walls, my neighbor will be planting in front of both of her walls (the woman behind her has chosen the plants). I will do that as well for the woman behind me for the lower wall. And I will be planting something in front of the upper wall (just below the terrace).

Yes, we will be covering quite a bit of the stone foundation of the garage. I assume that it was built up so far to make it possible to construct a garage on the slope.


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RE: Terracing/redi-rock retaining walls

I can't see those blocks without picturing Fred Flintstone sliding off a dinosaur, but if it's on the downhill/away side, whatever.

You're having these walls engineered, right? Please say yes.


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RE: Terracing/redi-rock retaining walls

Yes, we are, and the town building department inspects at several stages.

I'm wondering whether it might be possible to have a veneer of stone mortared on top. I will have lots of leftover dark stone, matching the garage foundations, from the old retaining wall.


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RE: Terracing/redi-rock retaining walls

Because everything needed for this project is already on site; heavy equipment, fill dirt, manpower...go for it! Savings should be considerable. Sounds like a win, win situation for you and the neighbors.


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RE: Terracing/redi-rock retaining walls

To me there are two issues, aesthetic and safety.

Regarding the safety issue, or "why would it fail?" your description of your neighbour's installation with pool reminded me of a local disaster in what might be a similar setting. I've attached a link to the news story. Basically, the uphill homeowner had installed a pool, plus it rained like crazy, and the entire slope gave way with additional weight of the water and I guess the resultant loss of structural integrity of the soil - I'm not an engineer, but that's how I understood it. The mudslide swept away two houses below. If you google around a bit on the story, you can find documents that show that municipal inspectors failed to mitigate what was an apparent risk, so it is worth thinking about this yourself. Your own wall will be further back from the precipice, plus you don't have a pool. All good. But perhaps the key will be drainage, to ensure that while the walls may catch rainwater, that they also release water in a controlled fashion. The current situation, where the soil sheds water, means it also doesn't get saturated. Now it will.

Aesthetically, I actually don't mind the industrial look of these bricks - I might take the industrial look and fly with it - some things just can't be disguised and might as well be celebrated. However, there are more naturalistic ways to terrace a yard, or more gradual approaches using more smaller walls. But you sound as if you have thought this out quite thoroughly and have a plan that suits your needs.

I would somewhat regret covering that beautiful garage foundation, but c'est la vie as we say in Canada, and I wonder if it can take the additional pressure from outside. Other than that, I can see that going for it is probably the right decision, with engineering oversight.

It's not just about it being the right thing to do, but also about doing it well.

KarinL

Here is a link that might be useful: Story of North Vancouver mudslide


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RE: Terracing/redi-rock retaining walls

What an awful story! But I think that we will be fine in terms of safety. The contractor has good references, and the wall system is supposed to be very stable. It sits on a large bed of gravel, and there is gravel behind it, so drainage is usually improved.

I am also sorry to cover the nice garage foundation, but I am tired of a yard that is a steep hill. I will have to look into what is behind the foundation wall of the garage - I don't think it's empty air, they must have filled it. The garage floor is cement.

I am re-thinking the 6' drop off the patio. I was not expecting it to be more than 4' - but I underestimated the grade change quite a bit. I am now wondering about a smaller wall mid-yard, and sloping planting beds from the patio to the smaller wall, with steps going through.

I don't dislike the look of the walls, but it is very different from the garage foundation, the house foundation, and some retaining walls along the driveway - all old, very dark stone.

I'm wondering about doing a stone veneer over the blocks.


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RE: Terracing/redi-rock retaining walls

These types of wall systems are designed to move with the ground. That's not to say that you'll see huge movement, but it's enough that a stone veneer will fail. You're better off mitigating the looks of the wall with plantings, or using a block that has a little more aesthetic appeal.


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RE: Terracing/redi-rock retaining walls

Unfortunately, there are only two choices in this material, the one in the photo and a more industrial looking, white, block. The company does make a third option, which would be better as it looks more like green/gray stone, but it is not being made in our area and is not available. I can't go looking around for different systems because this opportunity is here now.

I'm going to ask about options that do not involve a 6' drop off the patio.

Thanks for the information about the stone veneer, marcinde.


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RE: Terracing/redi-rock retaining walls

De nada.

As long as the blocks aren't painted and it's just a really light color from the Portland cement, you could always look into having an acid stain applied. I wouldn't go nuts with it, just maybe a gray and tan treatment so the blocks fade into the background more. As is, they're a wee bit front and center.


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RE: Terracing/redi-rock retaining walls

Boy those blocks are fugly there are some straight joints too and you don't want that in your wall marisany. Did you by any chance price out a natural stone wall just to compare the costs, it will be more but would this solve a lot of problems if you can afford it?


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RE: Terracing/redi-rock retaining walls

Thanks for the suggestion about the acid stain, marcinde. My neighbor heard that one of these walls in a neighboring town was painted by a group of HS students and now looks like it's been there forever. We're going to go and take a look at it.

inkognito, I have an idea what a real stone wall would cost, and it would put this project out of reach for us, unfortunately.

I am wondering whether we can do the wall at the rear of the property out of the blocks, raising the back of the yard 6', and then do the rest with small terraces that wouldn't need real retaining walls, maybe just a row of stone, leaving some slope between each level? The total grade change would be reduced from 16' to 6', and that in itself might make the yard more usable.


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RE: Terracing/redi-rock retaining walls

The 6' rise would be over what distance?

I don't mind the look of the blocks too much; they're better than others I've seen for the purpose. They remind me of a particular kind of stonework used for the massive foundations of some 19th and 20th century buildings. Maybe Romanesque, but I can't find a picture of stones cut with the really rounded edges I'm thinking of. [Somewhere, probably in Illinois or Ohio, there's a building with a grayish-tannish foundation that I used to see regularly....]

The color is a bit jarring. If that's not the manufacturer's "white" rock, the real white must be blinding.

Maybe if your stain your wall, the neighbors would do theirs too.


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RE: Terracing/redi-rock retaining walls

Sorry, it would be a 10' rise. The distance would be about 60-70', I think. Really less than that; if I raised the back and filled, it would be flat for a while, and then rise more sharply over a shorter distance, maybe 40-50'.

I don't mind the look of the redi-rock, as long as the wall was softened with plants, as much as I mind the discrepancy between it and the existing walls/foundations.

Does anyone know of websites with good inspiration photos of sloping, terraced yards? I tried google search but came up with spectacular huge gardens, not ordinary yards like mine.


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RE: Terracing/redi-rock retaining walls

If you're thinking of a 10' rise over 40-50', I'd definitely advise adding another wall. My backyard's much less steep, and it's no fun.

Make a mock-up on your patio (or another level location) with a piece of plywood. Prop up one of the short sides so it's 19-24" above the patio (19.2" over 8' is the same as 10' over 50', and 24" over 8' is the same as 10' over 40'). How do you feel about that sort of unrelieved slope over the majority of the backyard?


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RE: Terracing/redi-rock retaining walls

One wall at the back of the property that you really won't see, serving a basic function? Probably no biggie to just wing it. If you're going to start playing with terracing, and bringing other walls in for aesthetics and improved function, you may want to actually have your yard designed.

I say this because one of my biggest frustrations as a designer is getting brought in to design the plantings AFTER the hardscape guys have spent a year building walls in the most inconvenient places. I just went on a consult last night where the lot dropped off 30' from the back of the attached garage to the back of the property, and it was terraced with no real regard to anything but where they could stick a wall most easily. It was one of the ugliest hardscape jobs I've ever been asked to design around, and it's probably going to take me 2 hours just to measure the property and accurately locate the 11 different wall sections and 7 staircases (no joke).

Point being, it'll be well planted when I'm done and I'll mitigate the fact that the hillside looks like a series of machine gun nests the best I can, but the yard could have looked great had they started with an actual designer.

In this industry there are some great folks who can make it work AND make it beautiful, but a lot of them are better at one than the other. It's worth knowing what camp your guy falls into.


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RE: Terracing/redi-rock retaining walls

I agree, missing the obvious. The current slope is awful. It is hard to walk down the slope. The grass is all bent along the ground downhill, from water sheeting down. I was thinking that if I did the lower wall now, and brought the grade up somewhat, I could build on this later.

marcinde, you are right that I should have the yard designed. My neighbors' landscape guy is good at the mechanics but not a designer. My neighbors just wanted their yard flattened out so that they could have a pool. They won't even see their walls. I know what you mean about machine gun nests! I searched for terraced gardens using google images, and it was hard to even find one I liked! Most of them had way too many levels, too much hardscape, too many different plants - too much, in general. I would want something low-key and restful. I searched for landscape designers in our area, and found a website with and incredibly beautiful portfolio. But almost all of the houses were much larger than mine, with much larger lots. I'm sure this person takes on only very large, expensive jobs. I am also working under time pressure because the opportunity to have this done at a good price will disappear soon.


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RE: Terracing/redi-rock retaining walls

"But almost all of the houses were much larger than mine, with much larger lots. I'm sure this person takes on only very large, expensive jobs"

It's the catch-22 of being in business. You want to show the jobs that show what a rockstar you are, but these are also the projects that make many homeowners say "holy hand grenades, I'm not in their league!" It's worth at least calling and having a conversation. Estate properties make for really, really cool portfolio shots, and I do those. I can also rock a subdivision home like no one's business, and I'm guessing there are many designers like that too. Make some calls, you may be pleasantly surprised.


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RE: Terracing/redi-rock retaining walls

You're right - I looked at more of the portfolio, and some of the jobs were smaller. One of them was even at the level of simplicity that I want:

http://www.westoverld.com/portfolio_2.html

This one is spectacular:

http://www.westoverld.com/portfolio_1.html

but even if I had that house, I wouldn't want all those complex gardens, even though I love them, because I want low maintenance. In fact, even if I had the money, I wouldn't want a house like that, because I wouldn't want to take care of all that space.

I loved this photo that I found using google:

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Much larger scale than my yard, of course, but I love the look. You are not in my area (Westchester County, NY), are you marcinde? I don't suppose you do consultations at a distance?


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RE: Terracing/redi-rock retaining walls

I appreciate the thought! But, it's my firm belief that when you're talking about grading and terracing and all that, you need someone with boots on the ground to really get the feel of the space, as well as get all the grade data he or she needs to accurately design it.

If you haven't checked out APLD (the Association of Professional Landscape Designers)yet, it's worth searching for someone in your area. Not to say you'll find your designer there, but it's a good start.

The biggest thing is finding someone you feel comfortable with. If you feel like they get what you're trying to do and will design the space to what you want and need, and you're comfortable with the price - go for it. If not, keep asking questions or keep looking.


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RE: Terracing/redi-rock retaining walls

One thing you may have the luxury of doing is to break the job down somewhat, but you might need the help of a designer to do that wisely. That would be along the lines of getting this guy with this equipment now on-site to do the back wall, and maybe some grading of the rest of the site, with the full aesthetic treatment left for the designer to finesse with a different crew at a later date.

I too would encourage you to call that designer whose work you like to see if s/he'd at least come and walk the site and talk the options through. That may cost you an initial consultation fee, but it would be worth it to help make the right decision, whether they end up helping you do the project or not.

I don't know if you see it in yourself, but there seems to be a consistent reluctance to talk to people in a timely manner to ask your questions, from your delay in talking to this contractor (which you explain in your OP) to your reluctance to call a designer now. I recognize that trait because I have it! I never ask until I'm sure what I want, and often could have saved myself a lot of time and agony by opening my fool mouth sooner! So I'd encourage you to call this designer today and see if s/he could pay you a visit pronto, just for a chat to talk your problem through - a consultation, pure and simple. See where that goes. If you pay them for their time there is no obligation on your part to continue. And they may counsel you to go for it, as Nandina did above.

Key question might be how much you are really saving by rushing. That fill dirt can be left there until needed, so how much is it really to bring the crew and equipment back on site? How much crew and equipment is really required to do smaller terraces with smaller rock? An experienced designer will have costed this sort of thing out often enough to help you with that.

I totally agree with Marcinde that a person with expertise and boots on the ground is what you need here - there is only so much that strangers can do at a distance.

KarinL


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RE: Terracing/redi-rock retaining walls

Thanks, marcinde - I went to the website and found several nearby designers. It's interesting, I can tell from the websites whether I like their style or not. The ones I don't like are beautiful, just too much color, too much in general.

KarinL, you are completely right! I have some good reasons for not following through with talking to the landscape guy last fall - I was busy with work, kids, and an interior renovation we were doing, and I assumed that the cost would be too high. But you are right that I find the thought of calling a designer intimidating, both because I'm in awe of someone who can create some of the gardens that I've seen online and because I am afraid that they will find our budget laughable.

I did see a local designer on the ASLD website and remembered that my neighbor consulted her for plantings in her new yard. I have a call in to my neighbor to find out about her. From her website, I find her work acceptable - it doesn't take my breath away, but I like it.


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RE: Terracing/redi-rock retaining walls

Just for interest, have a look at the attached link.

Here is a link that might be useful: Nazareth Village


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RE: Terracing/redi-rock retaining walls

a couple of thoughts
what is the wall lined with? Did they use geotextile on your neighbors and are they planning to use it one yours? I know it may seem like a no brainer but last year i became involved in two projects with completely unlined walls that were already (after a year or so) showing signs of stress.

It may be hard to move quickly, but it is probably going to be worth it in the long run. Real stone walls are very expensive, and while they hold more value, they are difficult to afford compared to the redi- rock type walls. Just be sure to get a lot of details about how the wall is going to be built, and tell us the details so we can verify for you!


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RE: Terracing/redi-rock retaining walls

Thanks for the link, inkognito - fascinating project!

drtygrl, I am not sure about the wall lining. If I go ahead, I will find all this out, and thank you for offering to vet the details for me. I am somewhat fortunate in that my neighbor (male half of couple) is incredibly compulsive about any work done on the house. They have done extensive renovations inside, and he stays home from work and looks over the shoulders of the contractors. He does a lot of research before hiring someone. When he put in central AC some years ago, he interviewed 20 contractors. I did it a little later, and had two contractors come in, plus the one he used. His guy was much, much better than the others and he did a great job for us. More recently, he finally found a general contractor who satisfied him. I have used this guy for several projects over the last 18 months, and he is very good, completely honest, trustworthy, and fair. So I know that before having this extensive pool/retaining wall system built, he researched it thoroughly.

Some bad news though - the estimate from the landscaper finally came, and it is much higher than I expected. His initial ballpark estimate for the two walls was $16k. This would have left us some room in the budget for some upgrades. But the estimate came in at over $27k! I have emailed him to ask the reason for the difference.

Now I am thinking that, at most, I will have this guy do the lower wall/fill, as KarinL suggested above, and leave the rest to do later with a designer. But I will need to get some advice first.


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RE: Terracing/redi-rock retaining walls

Wow, thats a really big difference.


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RE: Terracing/redi-rock retaining walls

His explanation is that the block supplier has raised the price/sq ft by $3, and in his initial measurements he forgot to account for the square footage that would be underground.

Very disappointing.


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RE: Terracing/redi-rock retaining walls

Lesson for those in the business: never confuse people with "ballpark" guesses.


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RE: Terracing/redi-rock retaining walls

I agree ink - a ballpark price is a mistake.

And I really have problems with contractors who do business this way. A 70% increase on the price is not in the same "ballpark". Now you have to shop this around...sorry to say. Your neighbor got a good deal with what he thought was a quality contractor, but a 70% increase is not acceptable imho. I have had many clients balk at 10% increases over a the price of a project in past years. 70% is really a huge increase. I am sorry that this has happened - its a bit unusual for someone who does this regularly to "forget the part underground".


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RE: Terracing/redi-rock retaining walls

Yes, the 6' high wall has 1.5' buried underground. He just built two of these next door last fall!

I've asked him to quote the 6' wall and some fill/grading alone.


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RE: Terracing/redi-rock retaining walls

I may have missed where you're located, but if you have Versa-Lok available in your area, I'd give them a serious look. Beats the heck out of that "Fred Flintstone" look that someone referenced. I love their tumbled Mosaic walls. Their website has a dealer locator. http://www.versa-lok.com


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RE: Terracing/redi-rock retaining walls

Thank you, mnraindog. I'll give them a try. I also have another contractor coming by to estimate the lower retaining wall. I'm thinking of just having that one done, and filling in the low part of the yard, leaving the rest alone until I can work out a plan with a landscape designer.


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RE: Terracing/redi-rock retaining walls

We may be getting to a reasonable price for the lower wall alone and fill/grading. The current plan is to put a 6' (max) retaining wall along the rear property line, with fill from my neighbor's pool, and also to take some fill from the area just below the patio, leaving a sharper slope there (to be planted) and a larger flat area over most of the yard. This eliminates the second, higher wall at the patio (which I didn't really want). The excavation of that slope is necessary to get enough fill for the bottom, and it seems to make sense in any case.

I looked into the VersaLoc and, while it looks better and the material costs are lower, it tends to cost more because it requires more labor. It is also easier to use the Redi-Rock for walls over 4', because no grids are needed.


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