In this segment, we formed the south wall for gunite. The video, details and pictures can be found below.
The Video
Details
Order of the layers
We had formed previous shotcrete walls with steel studs and lath and steel studs with XPS insulation. We liked the idea of combining the insulation in the form because it saved us the step of attaching it, however, the steel studs caused “void shadows” in the shotcrete and water could travel thru those voids, etc.
For this south wall, we decided to use the steel studs to form the XPS, but we would put the shotcrete outside the insulation, on the opposite side from the steel studs. We could then use just a single layer of XPS and then backfill between the Studs later to increase our R value.
If this were a load bearing wall that needed to incorporate rebar in the shotcrete, we may have come up with a different idea.
Curved Bucks
To make the curved bucks, I used CAD software to figure out the size and angles of the little wood blocks, making sure that the longest side was something easily measurable on a straight edge. In this case, I used a 5 inch length (4.999 is close enough to 5) and an angle. I setup the miter saw with a stop block so I wouldn’t have to measure each one. Then I would just need to flip the wood board for each cut so the blocks came out with the right trapezoid shape to assemble into the circle.
Gallery
A picture is often the best way to tell a story, so here are a bunch of them.
Here David is a little annoyed because he is digging out the footings while Michael (on the right side) is having fun welding in the rebar for the last vault.
Yes, I know a screen capture is a better way to get these sorts of images, but my work computer has all sorts of “security” features that make it easier if I just take a quick photo of my screen. In this case, it was just to have some reference in my pocket while I was out there.
The elevation view of the front of the house…
Since we would soon need to put in the door buck for the front door, we really had to nail down the choice of which size door we planned on installing. We decided to go with this cheap and standard front door instead of the larger entry with sidelites that we had originally planned.
I had bought a new compound miter saw, but I bought a cheap “performax” one from Menards. It was impossible to align. I couldn’t even get the two sides of the fence to align with eachother. I ended up taking it back and getting a Dewalt, which I was very happy with.
I welded on these little brackets to attach the steel studs to the steel Ibeams
I had told the boys not to touch the bucks if they could help it, so Michael usually ran thru jumping like this.
We took a mini vacation with friends during this part of the build…
For the blocks we were cutting, I would often get a screen shot like this to remind myself of the angles and dimensions.
In this case, I had made sure that the longest dimension was a nice and easy 5 inches.
Putting that ring together…
We used glue and then screwed the blocks together
I liked the look of the end grain…
David getting some extra screws into the circle window buck.
I thought this pic of the boys helping to lift the window buck into place was pretty cute…
Windows bucks in, but still lots of work to go
Setting up the last curved wood ledge…
Brody doing some final adjustments as he attached the steel studs to the underside of the curved wood ledge.
Michael likes doing this thumbs up pose for the timelapse when he walks by
The XPS formwork is pretty much done here
DCIM101GOPROG0022660.
There is always maintenance to do. In this case, the new Kubota I bought needed a hydraulic line replaced. I took this pic so I could remember what fittings I would need.
Part of life includes stopping to sharpen your blades. That lawn mower had a rough life on that construction site. The three blades on the left are the ones I took off it and the new blade is on the right… Ouch, I have never seen such wrecked blades, so I took a pic and then had a conversation with the boys about riding the mower over rocks.
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.
It was time to shotcrete the central circle of the house. This post is mostly a gallery of pics to tell the story, but first, the video…
The Video
The Gallery
Extra time to add the mudroom roof
The rolled steel arches were welded to an angle iron bracket that was sitting on a concrete ledge and had been tapconned the wall. They were very secure.
Additional #5 rebar pegs were also added to the assembly to strengthen the connection between the roof and walls.
This shot shows the full length rebar spaced one ft from the steel arches and the pegs placed every 6 inches. This pic was taken before the last peg was placed over the steel arch.
This wider view shows the span with the rebar spaced no more than 1ft apart.
Kids love to climb.
They air compressor was helpfull for cleaning the dust off the footings just before shotcrete. You don’t want a layer of dust to contribute to a cold joint. You want the shotcrete to bond as well as possible with the footing and hopefully leave no cold joint at all.
Airial view of the shotcrete equipment setup and our formwork.
Michael and Sherri went around to do a final inspection and get some pictures.
In the background of this shot, you can see the strap I used to pull a stubborn wall form plumb.
Final inspections…
You can see the electrical conduit, etc.
We wrapped the concrete arches to protect them from the shotcrete overspray.
For this job, I got the articulating lift instead of the boom lift… We didn’t like it as much.
Here you can see the first pass of shotcrete and that a whole section collapsed. They came back and filled it in after the other shotcrete had stiffened up a bit.
Even thought we didn’t like the articulating man lift as much as the boom lift, we did like the lift company. We highly recommend wolverine rental.
The final texture was sort of smooth, but certainly not flat. It won’t matter to much since it will all be covered, and at least it was smooth enough to waterproof easily.
Here they are working on the wall in the mudroom. This is why I didn’t want to finish the roof. But once this was done, I could close it off.
David went to get my camera and move it at some point…
End of day 1…
End of day one and we had the north side mostly done.
The timelapse caught this by accident as Aaron was moving it. All the rest of the pics were a tumble of sky and earth, with this one stuck in the middle.
The nearest neighbors house looks quite nice on this fall day. I am sure the view in the other direction is not as pleasant… Sorry.
With the shotcrete only 16 hours old, we started to strip the forms.
Here you can see a closeup on an electrical outlet. The smurf tube did make a bit of a shotcrete shadow.
Here you can see the imprint of the particle board after removing the forms.
Hunter setting up the camera…
Paxton’s son, probably stretching a bit, after all that bent over welding.
Morning of the final shotcrete day… Still a bit foggy at 1000 ft elevation.
In these foggy pics, you can see the mudroom roof is ready to go.
Over the weekend, I also had time to remove the particle board from the apse parapet.
Parapet after removing the form boards.
If I had completed the span across this hallway, the guys would have had to shoot the concrete upward and probably would not have got the wall as solid.
This was the funniest thing… With the weight of the two guys and the heavy hose, they couldn’t get the basket to top back up again. I appreciated that they just went ahead and did the shoot anyway.
This was the minimal bracing that we put under the mudroom ceiling to provide a little extra support. I don’t know that it was necessary or ever took any load, but better safe than sorry.
This is how the mudroom ceiling looked after pulling away the formwork. Of course, we will plaster over this at some point.
THis is the mudroom ceiling after removing the bracing and boards.