When you are burying a house, one of the tricky bits is to keep the dirt from spilling where you don’t want it… Like into the doorways. I have a number of retaining walls planned for this build, and, just to keep things interesting, I have designed each one a different way. This section is about the “Heavy Stone” wall by the back door/patio. More details below, but first… the Video
The Video
Cost
I had assumed that those concrete blocks were the cheap way to build a retaining wall and the fancy quarried sandstone was the expensive way. Of course, I probably still would have used some real stone… However, when I looked into it, At least for the cost of the stone, the real stone was cheaper. Of course, that doesn’t factor in things like the cost of the mortar, which was about 5$ per level on my wall, so still not too bad. The real cost of building a wall like this is time… Those precast concrete block walls probably wouldn’t have taken me nearly so much time, but no regrets on choosing to do this one the hard way.
Engineering
Retaining walls often fail. Keys to keeping this one from going down included…
Wide heavy stones (heavy stone is actually what they called this size at the quarry) that are substantial and want to stay where you put them.
Leaning the wall back against the earth load. Before the earth can tip your wall over, it would first need to straighten it out. Gravity helps you keep things as they are.
Curving the wall against the earth makes it a lot harder for the earth to tip it over, just as it is harder for a mug to tip over than for a domino. Making the wall concave helps even further because the loads against it are in compression, something that the stone handles with ease.
Behind the wall, I had plenty of drainage. Drain gravel, landscaping fabric and HDPE corrugated/perforated drain tube were working to make sure that water pressure never gets a chance to build up behind the wall.
Layers of carpet were also used in the dirt behind the wall. This “geo-textile” idea is used by highway engineers to keep dirt from shifting under ramps. I would have liked to have used more layers, but some is better than none.
I watched lots of videos online about how to build a retaining wall that lasts. I recommend anyone who is planning to build there own do the same, and don’t be tempted to take shortcuts.
The Gallery
Here is a gallery of pics with detailed captions.
Here is the delivery. I paid 80$ per pallet, plus something (like 120$?) for the truck to deliver all the pallets.
Here are some more standard concrete retaining wall blocks. If you check the top right, you can see how many linear ft you get per block and calculate how many square ft of wall you would get per dollar. When I compared this with the cost of my quarried sand stone, my sand stone was about half the price.
Before I could bury the garage, I needed a retaining wall, but before the retaining wall, I needed some stucco over these fox blocks… This is just the scratch coat.
Partway thru the stucco job, I checked to see if the camera was still on. This is apparently how I look after a couple hours of night stucco work. (after finishing my regular work day and driving out to the site).
To get a gentle curve, I put down a 20ft long piece of 1/2 inch PVC going thru the marks I had made earlier. Then I put down mortar and started laying blocks.
After a few rows, the wall was already looking interesting and I was already learning.
After the wall was a few blocks high, I back filled for drainage. I also covered this all in landscapers fabric to keep the sand out. Actually, I came back later and filled the whole area with drain gravel, it is easy to use too much when you have a skid steer bucket and order by the dump truck.
After dark it starts to get harder to find the right stones. This evening I probably only got 3 layers in.
The 3rd evening, I got another 3 layers in before it was too dark to find rocks…
The rocks were all aligned against the front of the wall, but the back looked considerably messier. To sort that out, I used my mortar sprayer to shoot mortar over the back of the wall and fill all those cracks. I did it at several stages, this was the first. No pics of the actual shooting because I was busy at the time.
More progress… By this point, I had most of the basics down and things were moving along nicely.
Another pic…
Once the wall reached a certain height, I put these “benches” up against it. We had first made these for the ICF blocks.
Sometimes the kids seek out the camera to get a self pic or just wave at me.
Kids love climbing on walls. However, it can be a problem if the mortar isn’t set yet. This day it was before we started on the wall though.
You can see we have extended the platform. I also added wooden blocks to make it easier to scramble up, but I usually used the ladder.
Random pic
We named our dog Sandy to fit in to the site better. She loves getting up high and looking around.
Sandy chilling on the wall while I worked…
This is how it looks from the ground. I plan to add moss, creepers, etc.
Basically, the basement of our earth sheltered home was filled with approximately 11 cubic yards of concrete slag that needed to be broken up and removed so we could prep for pouring the basement floor.
It was something we have known we needed to do since last year, but were putting it off for obvious reasons.
Here is the video:
Why did this mess happen?
All this concrete was wasted shotcrete that wasn’t on the walls and should not have been on the floor either.
As you may recall, I had used steel studs to frame the basement and then placed metal lath on the inside to “catch” the shotcrete. I had been told (by the shotcrete guys) that the lath would be enough to prevent much of the shotcrete (peastone) from blowing thru. I was told to expect a thin layer of concrete on the inside, thin enough that it would break up into small fragments just by walking on it and that it would actually save me from needing to add as much pea stone later.
Watching the shotcrete being applied, it did appear that not much passed thru when it was applied at a downward angle onto the previous shotcrete. They did do it this way for the first couple levels, and actually raised a scaffold jack platform twice as they went. But then they got a bit tired and started shooting horizontally and even at an upward angle. This allowed much more shotcrete to pass thru.
The effect was cumulative with blow thru coming from so many different angles, each adding its own layer of concrete. The round central room was especially bad for this with at least 3 layers of 2 inch thick concrete across the floor.
And once the crew was working on the inner walls, there was also “rebound”, shotcrete that doesn’t stick to the wall, and “trimmings”, concrete that is cut off the wall because too much was applied in the first place.
All this concrete (that I paid for) ended up on the floor, but not in a good, “wow, you got bonus concrete floor along with your shotcrete” kind of way. On average, I would say we had about 3 or 4 inches across most of the floor (in several layers), and up to 8 or more inches near the walls, especially in the corners. It was uneven and lumpy and even had boot prints in it. The whole feeling was somewhat “war torn” and more than a little depressing.
When I setup the main level, I plan to back the metal lath with fiberglass screen. The metal lath will still provide the strength to catch the shotcrete, but the fiberglass screen will prevent any material from passing through.
Gallery
Thought I would try to put some extra pics in here…
David working on the concrete slag floor, he did a great job and filled up 33 5 gallon buckets of rubble.
David helping to tear out the old mess
And the Story.
I like to include the text of the video, along with some extra info that doesn’t fit in a narration, so that the content is google searchable.
For this job, I had hired some teens, rented a jack hammer and taken the day off work to make the long weekend even longer.
The big question was, “How would I get this slag out of the basement?” The final solution that I came up with was a Bagster dumpster that I got from Home Depot for 30$.
The plan was to load it up and use my trusty skid steer in to lift it up and out of the basement.
It took a bit of trial and error to figure out the best way to lift the bag and to empty it, but fortunately, we had lots of tries to get it right. You can see how we did it in the video.
The bagster is supposed to be for only a single use, but it held up very well, load after heavy load, for a number of days. The only tear was caused by dragging it up the rough wall in the first lift.
This first day, we were mostly focused on the edges where the thickest concrete was because I didn’t want to rent that 75 lb jack hammer for a second day. The heavy jackhammer was actually very effective on the thick concrete, but kept getting stuck in the thinner stuff. For that, the 11 lb breaker was much more effective. My Dewalt hammer drill also got a work out. At the start of the day, I couldn’t get the teens to touch the power tools, but by the end of the day, they were much more comfortable with me and the tools and were taking turns on the jack hammer.
On Saturday, my parents were in town, even though I warned them that we would be taking on the worst job of the build so far. I also hired Zack again, he was one of the teens from the day before.
My father got to cutting a slot in the footings (doorway) for the radon tube while the rest of us got cracking on the concrete slag. Our radon tube was made of a 4 inch corrugated drain pipe, wrapped in landscapers fabric to keep dirt out. It just gives radon an easy way to escape so it won’t build up under the basement floor.
Then my father and I worked on the floor drains while the others just kept right on cracking up that concrete. In order to get the slope correct from the floor drain in the central room all the way to the outer wall, we had to cut open the tops of the footings.
We had planned for holes in the footings to run these pipes, and I had even come prepared with 4″ PVC to use to form them. However, the guys doing our footings told me they brought their own 4″ corrugated drain pipe, which they nailed in place very quickly. The problem was that the flexible pipe “floated” up in the middle when the footings were poured. Instead of being a straight sloped hole thru the concrete, they bowed to the point that we couldn’t even get the 2″ pipes thru. I guess they were not used to the footings being so wide. Narrower footings probably wouldn’t have as much deformation due to “floating”. You may recall this same issue cost me time and money during several other stages of the build. Hopefully this was the last of it.
Then we came back out again on the holiday Monday, just my wife and kids. Sherri and I cracked things up with the 11 lb “breaker” and the boys scrambled to collect the pieces into the buckets. When the buckets filled up, one of us would dump the bucket in the bagster. The boys were motivated by being paid 1$ per 5 gallon bucket. They worked for several hours before wearing out.
With the big chunks finally removed, we raked the smaller bits and then brought in some pea stone, which is required by code in my area.
I came back on another afternoon with Zack and my friend Aaron to get the second half of the pea stone down and rake it all level. At one point in the video, you can see Aaron intentionally took a pea stone shower, just to see what it would feel like. I don’t think he will do that again.
The final product was a a peastone under-floor that meets building code. The black pipes are to channel radon out of the home and the white pipes are plumbing or drains. The inspector approved the work and we were able to rake the pea stone level and move on to the next step.
Next step is to get the vapor barrier, insulation and radiant floor tubes down here so we can pour the basement floor.
This video could have been about a lot of things… It could be about appropriate ways to get you kids involved in construction… Or about how I tried to hire for this basic task so I could focus on the trickier parts of constructing my earth sheltered home…
But in the end, the worked needed to get done, so I got my 10 year old to start on it one afternoon after work/school. David is a pretty good worker, but I didn’t mind him taking breaks (lots of breaks) with the bee bee gun. On another cool spring day, I went out there with my younger son. Generally speaking, they are very different personalities (Michael is also younger and therefore less suited to digging or working independently), but I was still pretty proud of how well Michael worked. He also enjoys the bb gun, but he actually spent most of the evening with me working on the rib forms (a separate video). On each of these evenings, we took a break to go walking (and shooting) in the woods.
That Saturday, the whole family came out. While I was working on welding steel arches (another video entirely), the rest of them got to digging. My wife, Sherri, did the majority of the excavation until the bedroom footings were completely uncovered.
I took the following Monday afternoon off work and came back out. This time, I managed to hire some students to excavate while a friend helped me with welding. These two teens were scratching their heads as they uncovered my footings like archaeologists with no idea of what layout to expect.
Side note here… I had some trouble with my generator (mentioned in another video) we ended up taking the carburetor apart, etc. It turned out the carb was fine. The oil level was just a tiny bit low and the “low oil” sensor was “almost” shutting things down as the oil was drawn up into the engine.
It took the teens several hours to clear the footings. My wife thought that was money well spent. Next I had them switch to clearing all the bracing wood out of the basement. We ended up moving it away with the skid steer. I offered them a 3rd job, but they were pooped and decided to go home instead.
Now that the wood is out of the basement, we can try to get these teens back to help clear the concrete slag out of there.
This first day, we were mostly focused on the edges where the thickest concrete was because I didn’t want to rent that 75 lb jack hammer for a second day. The heavy jackhammer was actually very effective on the thick concrete, but kept getting stuck in the thinner stuff. For that, the 11 lb breaker was much more effective. My Dewalt hammer drill also got a work out. At the start of the day, I couldn’t get the teens to touch the power tools, but by the end of the day, they were much more comfortable with me and the tools and were taking turns on the jack hammer.
The final product was a a peastone under-floor that meets building code. The black pipes are to channel radon out of the home and the white pipes are plumbing or drains. The inspector approved the work and we were able to rake the pea stone level and move on to the next step.
