This one is the long awaited shooting of the gunite roof. As per usual, we’ll start with the time lapse video and end with a gallery. If I am up for it, I’ll post some lessons learned in between.
The video
Lessons Learned
Gunite vs Shotcrete: This topic was already covered, but I’ll link to it here. I’ll also add that it is all in the mix. If your gunite is just a basic sand and portland mix, it isn’t going to be as strong as a shotcrete mix with some fancy additives, heavier aggregate, etc.
Lath and Screen vs Hardboard: For the shotcrete, the lath and screen worked well. None of the shotcrete passed thru the screen because it uses a pea stone aggregate. However, the gunite used sand as the aggrigate and did pass thru the screen. The hardboard was great in some ways, but the weather really beat it up and gave it a rippled surface.
Shooting and finishing: Both are important. My shotcrete crew could have done just as good a job as the gunite crew, but they didn’t. For shooting, you want someone who understands what you need to get done and is just putting up what you need. If they are paid by the cubic yard, they may put up more than you need, etc. You definitly want enough finishing people to finish the surfaces adequately. If your crew is strong on shooting, but doesn’t have enough man power to finish, you will be sad.
Cleanup… If the crew treats cleanup as an afterthought, you will be sad. There will be mess. Make sure the crew has enough man power to deal with it. Beyond that, you probably need to keep your eyes open for things the busy crew may miss. For instance, I wish I had better covered some of the near by boulders to prevent them from getting gunite on them and I really wished I had better cleaned off the polished concrete ribs before the gunite set. That mistake cost me many many hours.
Do it yourself? My rule of thumb is that if a job takes tens of thousands of dollars worth of specialized equipment, you probably shouldn’t be doing it yourself. Add the experience, skill and stamina required and I would double down that you probably shouldn’t be doing your own gunite or shotcrete. That said, I do know of some who have and kudos to them.
Gallery:
Here are the forms, ready to go. Everything was damp and unpleasant.
A panorama of the south side of the house. Today, the focus is the roof, but this crew will also do the south side walls and I’ll make that the next post.
Panoramic of the equipment that arrived the first day. If any job requires this much equipment to do right, you probably shouldn’t do it yourself…
Again, I know some people do their own gunite. I just wouldn’t recommend that for most.
Actually, this first mix wasn’t quite right and they had a bunch of yelling and hand signals back to the rig and made some adjustments. Once they had what they wanted, they moved pretty quickly.
The biggest issue in this pic, other than the momentous start of the long awaited gunite, is the mess streaking down the walls and over the floors…
This is about the point when the curved rebar conked in (curved backwards) in this one wide area. Not ideal.
Sherri and I working together to brace the ceiling.
Sherri and I cleaned up the mess. I think she is smiling because I said something like, “If I take the pic, everyone will think you cleaned this up by yourself.” And she said, “I am.”
By this point, the rest of the crew was packed up or gone. A very early day for a gunite crew because of Halloween. It was just a few hours.
Scott was quite the artist when it came to finishing work. He is also the owner of the company.
This is the finished guest room section. The 4 inch gap at the top end is to tuck the insulation and waterproofing under.
Here is the finish work on the first vault at the end of the first shoot day.
Unfortunately, this area got messed up by the hurried rain finishing with plastic over it the second day.
It went from being the prettiest to the ugliest. But either way it will be buried eventually.
It was never caught on film, but I was running ahead of the crew and used up 2 jugs of this stuff ahead of where they were shooting. This just helps the new bond with the old.
Here the mix needed to be thin so it could get around the pipe and rebar and fill the area properly without voids. But it was a bit too thin and found its way around the edge of my formwork and onto the floor below.
Here is a look at the mess below. It doesn’t look that bad here, but keep in mind that it was well over an inch thick. For depth scale, that doorway has a 2×4 across the bottom of it and the slope goes up from there. It took many buckets full to clear this up.
I did do a quick wipe down of the sides of the concrete ribs, but I didn’t do a good enough job and spent hours more polishing it later.
Here I am cleaning up the mess…
In the background, you can see one the plumbers who showed up on this crazy day. He is putting a faucet on the outer wall.
See the video for more detail about what is going on here.
I got to try the Gunite Nozzle for a few minutes. Fun isn’t the right word for it, but I was glad I got a try.
After cleaning up the mess in the guest room, I put up this plastic to catch the mess in the first lath vault. This vault was two small with two tight a radius of curvature to use the hardboard panels.
I basically put up sticks of scrap wood with plastic screwed to them. I figured the plastic would catch the mess.
You can see that the quick-thinking sticks and plastic plan did hold up. I was pretty happy with myself at the time, but less happy when I tried to get that down after it hardened.
Not always as smart as I think I am. ¯\_(ツ)_/¯
Carlos and Ben Shooting.
I couldn’t tell if Carlos wanted me to take his pic or not. On the previous job, he was downright posing for me. But this time, he seemed a bit more reluctant. Maybe it was a bad hair day. 😉
Here Carlos is going to relay a message (via hand signals) to the rig crew.
You can also see inside that vault to the mess that fored on the plastic…
For this second lath vault, I just had enough time to cover the wood and the sand, and I had already started thinking about how I would get the mess from the earlier vault down again…
But I did end up needing to spend about 8 or more hours cleaning the ribs off later. They had so much gunite on them. I really should have washed them right away.
All the wet gunite in here gives it an interesting look.
We plan to “wet seal” these ribs when the whole thing is done, so we’ll see this again, without the mess.
Check out this guy, just standing on the edge like it was nothing…
This was the best pic. The gunite looks so soft and velvety.
This was a rare opportunity to get really close for a pic.
This went on all day, so I got a few similar looking pics. If you are wondering why I showed so many, you should see all the ones I didn’t show 😉
Especially after that first section conked in, it was pretty brave of the crew to keep on going.
Here is a momentary balance shift and recovery. It is pretty dangerous work.
The sun had set not long ago, now everybody goes below. To take a bath in one big tub. With soap all over, scrub scrub scrub.
Bonus points if you can name that author 😉
The panoramic feature on my camera did something interesting with this roof shape
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.
Our earth sheltered home has some interesting design elements, and at the center of all that is the tower. This post is about how we setup the formwork for the tower and the mezzanine next to it. I’ll tell most of the story in the descriptions in the gallery, but first, the Video…
The Video
The Gallery
Most of the story is in the descriptions
Before we started on the first day, I worked out the dimensions on the back of a pizza box… Here you can see the 4th window that we didn’t end up actually putting into the wall.
A cross section thru the tower and mezzanine
Plan view with more detail then you need right now
Michael using a heat gun to soften the PVC pipe so we could curve it. The heat gun came from HarborFreight and cost about 10$
Curved pipe slipped thru the holes in the steel studs.
Setting up the steel arches so they would be embedded in the wall… The ends were trimmed to fit the bracket on the outside wall.
End of the first day…
John showed up and helped us with the kitchen wall. We figured this was a good time to add this to the task list even if it wasn’t really part of the tower or mezz.
We reused the PVC pipe template to check the rebar curves for that wall.
Sherri overcoming her fear of heights in order to get the Electrical done.
We placed the steel arches on steel angle iron sitting in a pocket on a ledge. The tapcon keeps the bracket from moving left or right until the concrete is in place. The ledge keeps it from moving downward.
We welded the steel arch to the bracket to keep it from twisting, etc.
Steel arches in place will eventually form the structure of this roof section.
To install the windows, we first drilled holes in the steel studs using self tapping screws because they actually work better than drill bits for this application. Once there was a hole, we could back out the self tapping screw and drill another with it. I only used two screws to drill all the holes and that was just because I dropped one. After all the holes were ready, we lifted the wood bucks into place and put wood screws thru the holes into the wood.
Installing the 3rd window.
David pointing this out
While we were working, the turtles in this area were all digging holes and lying eggs. This one was about 1 ft from the house, right outside the window.
Lath washers and screws were used to attach the 4 inches of rigid insulation
Before working on the wall, we tried different things Here I was putting the screws thru some chunks of insulation to see how well they would hold, etc.
On the flip side of the practice piece, you can see that I was originally using bottle caps to catch the screws. We eventually decide they didn’t grip strongly enough and switched to treated wood.
A quick selfie after building the walkway. This walkway will let us build the top half of the mezz safely.
Here the mezz is wrapped in 4 inches of insulation. The gaps with no screws will be cut open to reveal the windows. We did it this way because it made it much easier to get a constant smooth curve.
On the back of the wall, you can see all the little wood blocks that hold the screws on. These were put on the ends of the screws as they came thru…
A closeup of the screws coming thru the wall. After concrete is added, they will also be embedded in the concrete.
Sherri working away on electrical…
At this point, the mezz is mostly done and we are ready to turn our attention to the tower. The original plan was to attach the formwork to these steel studs, but we decided to cut them out and attach directly to the heavy steel columns.
Here we cut the first window out of the insulation
First window in the Mezz
Here is a closeup on the window. This will all be covered in about 3/4 inches of stucco.
Electrical conduit in the corner of the Mezz. These pics will come in handy when we are trying to remember where these tubes are.
Plastic over doors and windows is just to keep the concrete out of those areas.
In this scene, i am using the AdirPro laser to mark the top level of the wall. The insulation actually goes higher than I want the shotcrete to go, so I used the laser to mark the studs and then ran a red wire around the perimeter at the right height. My plan was to ask the shotcrete guys to level it off at that height so I would have room for the quad deck above that… It actually worked out better than I hoped 😉
David in the shop. Often, while moving the time lapse camera around it will catch something interesting. This was one of those times.
This was the final design for the portholes. Basically, an ellipse with a 45 degree champher glued to two circles for 6 inches of total thickness.
We “glued” the XPS layers together with a paint primer called Gliden Gripper. Special effects artists swear it is the best glue for XPS and also happens to be the cheapest and easiest to use.
I made a master ellipse and circle template out of thin plywood and then we traced these out and cut all the pieces out with a band saw…
Sherri showing her latest scratch to the camera.
Michael Jig Sawing out some smaller shelves for the gaps between the concrete ribs.
I wasn’t there for this, but presumably david was playing with Sherri…
Michael setting up the camera for me…
Our formwork for the tower was utility OSB, but we didn’t actually buy many new pieces. The majority was recycled from the previous job.
Taking a short break between panels
Here the tower is mostly done
I was worried that the soft arch tops would deform under the shotcrete load, so I inserted XPS cut to the right radius to hold the shape… Glad I did.
XPS to help the arch hold its shape under load.
These crimped Pex connections are really the best. This blue pipe will carry water up to a hose on the roof.
This is the best way to make pex connections, by far… The only downside is the initial outlay for the tool, so I got a used one. Don’t worry, I still test the connections and can say the tool still works perfectly.
Pex connection wrapped in stucco tape to keep it from corroding in the concrete
Inside the tower
Tower Assembly
All these steel beams are there to keep the loads off the front windows that will line the south side of this building
A boy and his dog borrowed my camera
Our new puppy on site… We named her Sandy.
Lots of building together means lots of time to chat… Even if it is >10 ft off the ground.
A view back toward the mezz from the tower.
I used a laser to line up the heights of all the porthole windows. Instead of a tripod, I stacked wood blocks to get the assembly to exactly the right height.
Here I put the laser glasses over the camera so you could better see the line.
Porthole windows in place
The portholes were screwed to the walls. THe hole in the middle of the circle was because my screws were only 5 inches long and wouldn’t have reached thru all 6 inches.
Window Forms in place
Eventually it was all done
Our structural inspection sheet is very much longer than usual. Our new inspector said it was longer than the Bible.
Our shotcrete guy (who didn’t actually ever come out) said my tower needed bracing. I tried showing him pics of the steel skeleton, but he didn’t understand how rock solid it was and insisted that I also add 2×4 bracing. Waste of time and wood, but I did it anyway.
In prep for our electrical inspection, we setup the boxes, connected with ENT conduit and also had to to run the wires.
Wiring as seen from the inside. You can also see some of the basalt rebar mixed in (the thinner ones)
Here are two types of rebar. The top bar is half inch steel rebar. The lower bar is 3/8ths inch basalt rebar.
Our electrical inspection sheet is also much longer than usual. Good job Sherri.
Sherri passed her electrical inspection.
I wanted to compare 2 laser levels… This is the Bosch
I wanted to compare two laser levels, this is the AdirPro. I think it is slightly better than the Bosch.
For the last mezz wall, we started with the rebar and attached the rigid XPS to that. This is how…
I used the bits I had been cutting out of the boards to form the tower to form these ribs for the ceiling over the stairs.
Then I ran stringers
Then I placed wood over the assembly… Note that I didn’t do too fancy of a job. This is just for the ceiling above the basement stairs and I can stucco over any irregularities it caused.
