In order to bury the office apse at the front of our earth sheltered home, I needed to build a retaining wall with a window in it. For this corner of the build, I decided to use CMU’s, Concrete Masonry Units, AKA concrete blocks. We also had to insulate the apse structure.
I may come back and add some detail here. For now, I’ll just post the video and gallery of pics to tell the story.
The Video
The Gallery
Here are some pics to help tell the story.
Sherri getting a selfie
Sherri and I decided to roughly imitate the “American Gothic” paining.
Sherri and I decided to roughly imitate the “American Gothic” paining.
Couldn’t hold the straight face
And back to work…
Camera caught a block drop in mid air and I thought it looked worth keeping.
Michael’s turn to get a selfie
We put 4 inches of XPS between the apse and the retaining wall. This first 4 feet were easy because of the simple curvature.
My mother faithfully working on the insulation dome.
Here Michael is cranking away on the dome. You know this process is decent when an 11 year old kid can crank it out.
Posing with my subway vinyl. In theory, you are only supposed to use these with the image downward, but I couldn’t resist.
We glued the vinyls together with HH-66 vinyl cement. It basically melts them together with a chemical bond.
Perspective…
Here you can see that the insulation layer completely separates the inner and outer walls. The rebar and lath were covered in concrete, ferro-cement style.
It was getting dark by the time I got that concrete up on the eyebrow.
The insulation mosaic was rough looking, but functional.
Go pro caught this fun one as I drove by… I guess I was looking at the camera to avoid driving over the tripod.
After waiting more than 2 months for our shotcrete crew to come out, we managed to find a new gunite crew in the area. S.A.M. Pools came out and did a great job. We can talk more about the details in the blog, but first, the Video.
The Video
The Wait
Waiting for contractors is just a normal part of building. It just gets worse when you are an independent builder because the contractors all have more regular clients that are more important to their long-term success than your “filler” job.
We couldn’t get our shotcrete guys to come out and the summer was fading away, so we began the search for a replacement. Gunite and shotcrete crews don’t seem to put any effort into direct advertising. Most don’t even bother listing their phone number anywhere, never mind having a website. Instead, they work for landscaping and pool companies.
So I began to call those sorts of customer-facing companies. However, those companies do not want their subcontractors getting other work because it could lead to increased prices and reduced availability. I could see that they had done shotcrete work based on pics on their website, but when I would call, they would only tell me that they subcontracted on an as-needed basis and would be happy to manage our job for us.
In a few cases, I managed to find the names of some of these subcontractors and mostly found that their motivations were similarly frustrating. Keeping the landscaping and pool companies happy was their primary motivation and my side job was just a distraction. I actually had a few of these companies out to look at my site and give me a quote. But then they were all solidly booked and said they would keep me in mind if a bigger job every canceled on them and they suddenly need work. In other words, I could be lucky enough to be their back-up plan, but would get very little notice.
And then I somehow got the name of S.A.M. Pools. I can’t even remember the chain. I have several contractor friends and I think one of them gave me the name of a guy who has quit the business, but gave me the name of another guy who knew Scott at S.A.M. Pools. When I had started my search a couple of years before, they were a pool plastering company, and it was only in the past year that they had bought a gunite rig. Even now, a year after doing my job, their website (much better than most) still doesn’t mention a single word about gunite.
So, when I called Scott (the “S” in S.A.M. Pools), he came out right away and gave me a quote. We considered it, did some math, etc. and found it was on the high end of the range of what we had paid for shotcrete, but at least it was in the range (our Shotcrete prices had varied wildly). The quote also said he could start the following week. I texted him over the weekend to say we accepted the quote. I just went back to find my exact words… After saying I accepted, I said:
He immediately phoned me, seriously insulted because he had already told me that he would be available and did I not think that within a week of giving the quote was soon enough! Of course, I apologized for assuming that he was like the others who had given me quotes without any plans to actually show up. We coordinated based on weather and time required to get the supplies delivered and booked a date for gunite on Friday that week.
This was after about 11 weeks of waiting for the previous shotcrete crew, so I was nervous all week that they would finally become available and I would need to decide to decline one or the other. I needn’t have worried. After the gunite was up, I texted the shotcrete crew to tell them they didn’t need to worry about doing that tower any more because it was done. They wished me good luck.
Differences between Gunite and Shotcrete
Gunite and Shotcrete are more similar than different, but lets talk about the differences. I have now had two crews work on my site, the first was shotcrete and the second was gunite. Primarily, you should care about the fundamental differences between the methods. However,there were also significant differences between the crews that I personally worked with. I’ll try to keep those separated. The crew stuff belongs here in the post about my own personal experience. The fundamental differences in the method belongs as one of the technical posts.
The Crew
Let me start by saying that I appreciate any crew willing to come out and help on my project. This goes double for something as physically demanding as shotcrete. In full disclosure, I should note that I have since had a falling out with the previous shotcrete boss because I wouldn’t remove the Youtube videos after many negative comments came in (the internet is such a friendly place), so I won’t mention any names here and will try to be as fair as possible (actually, I am being very generous).
The shotcrete costs were wildly erratic and often doubled the quote. The unpredictability was very stressful and always ended up much more expensive than I budgeted for. In contrast, the gunite crew gave me a quote and it was exactly that price at the end.
Communication between jobs and during the jobs was so much better with the Gunite crew. Messages were promptly returned with phone calls and rapid resolution, etc. The only thing that wasn’t rapid was sending us the bill. Meanwhile, the shotcrete boss left me with hundreds of ranting text messages. Some optimistic or fact-based, others swearing at me and calling me an idiot, and then followed by more positive ones and then almost all very negative after we switched to the gunite crew.
The quality of the work was the biggest difference. The gunite crew used measuring tapes, cleaned up their messes, and produced smooth flat plumb walls. In contrast, I never saw the shotcrete crew measure anything or use a single level, they left (literally) tons of mess for us to clean up and the walls were very rough despite my many pleas to have them smooth things out. I don’t know what portion of the low quality was due to apathy vs skill level, but, in theory, a shotcrete crew could get the work just as nice as the gunite crew if they had the skill and wanted to.
The Method
Differences such as the compressive strength or durability of the concrete (its all about the mix), the slump of the concrete, the pace of the work and even the weight of the hose are technical differences compared on this technical page.
The Galery
And here are some pics…
They dropped off supplies and equipment the day before. This got me excited 😉
This part of the gunite pump works like a geneva drive from a film projector, except it moves pockets of mix instead of frames of film.
Bert was great with the Skid Steer, running it around at high speed.
Joe keeping the rig going
Walls were done one level at a time.
planning the ladders for the next section of tower
Back wall of the kitchn
Behind the stairs after the second pass
Mezzanine after the second pass
second phase on the tower
Cleaning up the tower after the second pass
Master Bedroom eyebrow after its first pass
Eyebrows after a pass or two
Eyebrows after the second pass
Mezzanine during the 4th pass
Michael picking up the camera and taking a quick pose
They got the office done before the weekend. I kept it wet to improve the cure.
Office completed, you can see all the rebar chairs on the inside
Behind the gap between the two eyebrows
Almost done the eyebrows
The final edge of the tower
All done
Tower pass thru
Looking up in the finished tower
The wide angle camel unravels this tower
Carlos after finishing up
A look down into the tower. In the original plan, all the concrete ribs were supposed to be a few inches further out so the tower would have had a smooth inside. Oh well, mistakes were made and the house is a little smaller now 😉 All due to rushing on the day the crane was there. I’ll work some sort of book shelf into it and it should look fine.
Carlos enjoying the view after he was done
They were able to clean up this nice ledge so I can set my quad deck slabs up here easily.
You can see the wire that I tied at the right height. Then I asked the crew to trim off the concrete along the wire.
Jimmy after shoveling out this big pile of rebound and trimmings
Taking away the rebound with the skid steer
Cleaning up with the skid steer
Bert dumped the rebound on my concrete waste pile on the back side of the garage
After they were done, the rain picked up, which was just perfect for curing the concrete
A few weeks later, I began to strip off the forms
A few weeks later I started to tear off the forms.
While we were waiting for the shotcrete crew, we continued on some side jobs. One of which was insulating the skylight curbs and protecting them with stucco. Detail on our mix recipe, etc. later, but first, the video.
The Video
The Mix
Here, we used the scratch stucco recipe of
5 buckets (25 gallons) of sand
94 lbs (1 bag) of portland cement
17 lbs (1/3rd bag) of hydrated lime
We mixed this all dry and then used buckets of the mix, mixed with water (about 20 cups) using a drill mixer. After applying the stucco (it naturally forms a layer about 3/8ths of an inch thick), we used a “scratch” tool to give it texture so the second layer would grip it well. Then we left it for a few weeks to cure and watered it often to increase the strength during the cure period.
The recipe for the brown coat was very similar, except with 10% more sand and lime to weaken it a little bit. You want the brown coat weaker so that if it tries to shrink as it cures, it will crack instead of cracking the scratch coat off the wall.
Before applying the brown coat, it is a good idea to wet down the wall. Otherwise the moisture from the fresh stucco is sucked into the scratch coat and it is difficult to work with.
After applying the brown coat, we continued to water it for another couple weeks, again to improve the cure and the strength.
Improved mix
As I mention in the video, along with our improving stucco skills, we also experimented with the mix and found that adding a quart of thinset after mixing in the water really improved the workability of the stucco. It also improved the stickiness (important for ceilings) and gave it some waterproof characteristics also.
The Gallery
Again, sometimes the easiest way to tell a story is as captions on pictures.
The skylight concrete would have leaked a lot of heat. So we needed to wrap them in insulation. But first we needed some wood to screw the insulation too… Necessity is the mother of invention.
This side of the skylight needed more insulation because it included some vertical ducts. I decided I would need to extend the electrical box a little. This was not enough.
In one of the first attempts, it became clear that the electrical would be too recessed.
So, I ended up using a bunch of outdoor box extenders… If it looks stupid, but it works, its not stupid?
Another view of my stacked electrical.
The outlet after we got the stucco around it
Eventually, we covered the wood tops of these with copper…
