After completing the footings, the next step was to erect the steel studs and metal lath that we would shoot the concrete (shotcrete) against. You can think of the steel studs as fancy integral formwork. I had had some trouble up front getting the steel ordered, particularly the steel studs. So I went with another company to at least get the track (including Flextrack) ordered. This let me put the track down first while I wait for the steel studs to arrive.
Basically, track is needed to hold steel studs in place. The studs hold the metal lath and the metal lath will catch the shotcrete and shape the walls.
I originally had this part of the job in my gantt chart as a 6 days’ worth of work starting the first week of May, so I started last week about 7 weeks behind. To make matters worse, I ended up working on it over several partial days spread across a week and I haven’t even started on the vertical steel studs. I would guess that by the time I am caught up on putting in the steel studs, I will be about 8 or 9 weeks behind. Winter is coming, but I will resist the pun of saying that I am working to get back on “track”.
There is definitely a learning curve, but I consider the basement as practice for the main level and I was definitely faster by the end (as you can see in video). Knowing my velocity (per ft of flex track or straight track) lets me better estimate the time (and resources) I will need to complete the main level.
Here is the time lapse video.
On to the story.
Like an ant moving a mountain, I am just doing things one bit at a time and trying not to be overwhelmed or forget anything. For this past week, the first step was preparing a simplified version of my drawings (a basic shop drawing) with just the door buck and track dimensions labeled.
Measure twice, cut once… But first make sure you know what the measurements should be. And simplifying the drawing to show just what you need does help… But make sure you also have an idea of the other bits that will interact with that or you could get yourself in trouble.
The next bit was putting together the bucks. I decided to do that at home where I have a chop saw and a garage to work in. I cut and labeled all the pieces and loaded them (un-assembled) onto my trailer. The bucks are made from 2×6 treated lumber. They are 6 inches taller than normal because I am fastening them to the footing and will come back and cut off the 6 inches at the bottom after the shotcrete walls are in place. Then I will pour a floor to make up that 6 inches.
Others might have built the walls on top of the floor, but my “wall first” approach uses the floor as a shear plane against lateral earth loads. “Walls first” also makes the shotcrete installation much easier because it covers up the joint between the wall and the floor (so they can be less picky about it) and because they don’t need to shovel the “rebound” out of the basement. Rebound is the “pea stone” and cement that bounces off the wall during the shotcrete process. It can be up to 10% of the volume of the walls, which for my basement would be nearly 4 yards. Lugging rebound out of the basement would have been hard work for the shotcrete crew and would have cost me a lot of money.
I added my generator to the trailer (needed to power my hammer drill) and headed to pick up my supply of steel. The look on the guys face when I pulled up told me he was pretty sure it was amateur hour, they told me that there was no way they could load my steel onto that trailer. I quickly told them that, “This steel order weighs 660 lbs. I already have 332 lbs of 2x6s, 55 lbs of 2x4s and the generator weighs 163 lbs. My trailer can handle 1100 lbs and my car can two 2000 lbs, so we are all good.” I had just guessed at the generator weight, but my rapid fire numbers somewhat startled the loading dock guys for a moment and convinced them that I was serious. While they were recovering, I quickly took the back and side off my trailer and unloaded the generator so they could set the pallet of steel down with the fork lift. One of the guys helped me load my generator back on top again. Still a bit concerned, they asked me how far I was going. All I could say was, “All the way.”
Sherri said I should probably never show anyone this picture (above), but I think it shows that “where there is a will, there is a way”, even if you can’t afford to look like a pro and you end up being chuckled at by a couple of loading dock workers.
My Brother-in-law, John R., came out to help me assemble the bucks. With everything pre-cut, it was pretty straight forward. We would have screwed them into place, but I forgot my hammer drill. It took more than half an hour to get three Tapcon screws in with my regular drill. That was a waste of time, so we focused on leveling the steel storage container and getting ready for more productive days ahead.
To level the 4800 lb steel container, we used a hydraulic mechanics jack to lift one side and then we stacked bits of waste concrete (that the trucks had dumped on the sand) like a dry stack foundation wall. It looked pretty cool; I should have taken a picture before we covered it with sand. The process went pretty smoothly, but it was hot & tiring work, so I really appreciated John’s help.
As a consolation prize, John went home with a really bad sun burn.
I came back on my own with the hammer drill and got to work on the steel track. The footing is full of ¾ inch stones. It is a lumpy surface to work on, and depending on the underlying stone, the drill could go thru like butter or struggle and fail to penetrate at all. I often found that moving a few inches over was easier than trying to push thru a hard spot. Sometimes I had to try 2 or 3 spots before I found a good one.
After drilling the pilot hole, I would switch to my socket drill to drive in the Tapcon screw. I quickly found that the torque setting on my drill was also helpful. If I set it above 15, the Tapcon screw heads would just snap off. Still, it was often a frustrating struggle to get the Tapcons to screw into the harder spots. I worked until I ran out of screws and my cordless drill batteries were dead.
You may think I should have planned better and brought the charger, and you would be right, but at the time, I was tired and glad to have an excuse to go home.
The next day was my oldest son’s 10th birthday. I ended up taking him out to the property to help out. Having learned my lesson, I took my dwalt battery charger with me so I could charge one battery with the generator while using the other one in my driver. On the way, we stopped and picked up some more Tapcons. I also bought a box of smaller Tapcons (3/8ths instead of ¼), to see how they compared.
My initial plan was to use the larger Tapcons on the ends of the studs and the smaller ones between, but that was hardly necessary. The smaller Tapcons were just so much easier to drill and screw than the large ones. I ended up using up the box and buying another rather than keep using the larger Tapcons. The smaller 3/16ths Tapcons also cost 35% less than the ¼ inch.
I started out using ¼ inch Tapcons which have 1160lbs pull out and 900 lbs of shear resistance. Clearly that was overkill. The 3/16ths Tapcons had 900lbs pull out and 720 lbs of shear resistance, which should be more than enough to keep the wall in place while the shotcrete is applied. For the door bucks, I used several of the large ¼ inch by 3-3/4 inch Tapcons.
For the flex track, I bought very simple track. It doesn’t have the metal straps or locks or other “structural features”. It is simply cut so that it will stretch on one side. The shape is held by screwing it to the concrete. The fancy “structural” flex track is ~$2.70/ft and the simple stuff I bought is only ~$1.19/ft.
I had marked the footings at the right radii so I could lay my track. As a novice, I pulled the track into position, the stretching was uneven. I later learned that I could get a much more precise (and rapid) curve by inserting a screw driver and twisting to widen the outside side of the track. More experience and I found that two twists in opposite directions resulted in a more level track.
The close up install video is here.
I had to go back for a third day to put in a last few hours and get the job done before my son’s birthday party this weekend.
Next step is a small job of putting together the window bucks while I wait for the vertical studs and scaffold tower to arrive. Both should arrive next Wednesday, along with some family and friends to help erect it all.
Today was day 3 of the footings… Our first day pouring concrete on the site. The actual work was really all done in about 2 hours, half an hour if you just count the concrete pour time, so it is hard to call it a day. The inspector, Dale, needs to check the footings before the pour and his MWF 10 to noon schedule meant we couldn’t fit this into Monday afternoon like the footings guys wanted.
Here is today’s timelapse video;
Thunderstorms were predicted for 1:00, so I called the building inspector to see if he could put me early on his rounds. He agreed and put me first. I texted Doug Dysert by 8:30 and hoped that would be enough lead time to move the pour earlier…
The inspector arrived just after 10 AM. Keep in mind, this was my first inspection, so I was a little bit nervous. The first thing he did was check out my posted permits. Then he went down into the excavation and gave the forms a good look. The inspector was actually very friendly and said the design was a “work of art” and the execution was “very well done”. He found a couple spots where the rebar was a bit too close to the boards (there is supposed to be at least 2” between the rebar and the forms) and told me to sort that out before the pour. We chatted a bit and then he handed me my “Inspection Notice”, with “approved” written on it. He left by 10:15.
I texted Doug to say we were all ready for concrete, but it turned out that the concrete was scheduled to come at noon anyway. Two of Doug’s guys (Don and Chris from the previous day) arrived at about 11:45. The concrete mixers (two of them) and the pump truck all arrived around noon. It was pretty awesome to see the pump truck extend its huge feet and then unfold its 135 ft arm. I wish the timelapse camera had been angled to catch it.
The concrete pump truck was pretty huge. Its 400 horsepower Cummins diesel motor powers 4 powerful pumps that push the concrete at 4800 psi. The operator told me that he could pump up to 210 yards per hour, but he had it set on the slowest possible setting for my small job. I got my order slip from the driver to confirm that it was 2500 PSI concrete with a slump of 5 inches. It had the ¾ inch natural stone aggregate (6A) along with sand and fly ash.
Fly ash is what Charles Dickens would have seen coming out of the smoke stacks of dirty coal factories before they started capturing it. Trapping that pollutant it in concrete is a good thing. It is also pretty much free (waste product) and replaces some of the Portland cement, which has high embodied energy (and cost). Its tiny particle size increases workability (think tiny ball bearings) of the concrete, so the water content can be reduced, which increases strength and durability… It is really a win-win additive.
Then the clouds parted and the sun came out. The concrete got pumping and things went pretty fast after that. They pumped out most of the 23 cubic yards of concrete in about half an hour. I don’t think the crew had enough people to keep up like they would have preferred. I jumped in to help with the screeding. Even the pump truck operator helped moved the concrete pipe around when he got tired of waiting. The concrete was pretty thick with ¾ inch stones. None of the footings blew out, but it did bulge in a couple spots, which used up more concrete than we were expecting…
For footings, they just screed, they don’t trowel or float. Since the tops of the forms were already level, screeding was just a simple process of “sawing” a board back and forth over the top of the form to level it out.
We ended up needing to use the concrete that was in the bottom half of the long pipe to fill in the last bit of the forms. The pump driver basically dumped it on the sand at the top end of the driveway and we had to bucket it over and down to the footing. Don was using a 5 gallon bucket and I was using a 2 gallon bucket (only other bucket available), but I joked that at least I was filling mine up all the way.
With the last bit of concrete, I built myself a 5 gallon bucket rocket stove. I made the inner form out of cardboard (the night before) and wrapped rope and saran wrap around it to “spiral” the flow. My hope is that it will make a little flame tornado that will push even more heat into the concrete and increase the draft further. I’ll make a separate post on that if it works. This concrete wasn’t exactly designed for high heat so it may not last long.
Then the rain came down again. It was actually a line of storms, hundreds of miles long, all lined up to pass over my site, and nowhere else. They guys thought it would blow over soon and decided to wait it out in the truck. I got in with them and asked how long we would be able to push the vertical rebar dowels into the concrete. They told me not to worry about it, we had “hours”…
Well, nearly an hour later, and the township tax assessor called and asked me to drop off a copy of the plans. The assessor had been out to view the site while we were not there and was totally confused by my footing. She was only about 2 miles away, and I wasn’t doing anything right then, so I took the plans over to her. I hope she devalues the home as much as my bank’s appraiser does. Unfortunately, she seems to like it.
When I got back, Doug was on the phone. Understandably, He didn’t want his guys to sit there waiting any more. He said they could just drill the rebar in later (for ~60$/hr). As I hung up with him, the rain stopped. We went down to check out the concrete and found it was already too stiff to hammer the rebar into anyway. It wasn’t my plan, but now I will have more time to carefully mark the position of the dowels, so it may be for the best.
Not sure if it was just the dollars talking, but Doug really didn’t like idea of the PVC tubes as rebar receptacles. He pointed out that they would be a weak point in the connection between the footings and the rebar. They do not have the strength or the grip. I was more interested in the convenience because I don’t think I need strength or grip in that location. Perhaps we were thinking about different locations. I agree drilled rebar will be critical for the pillars under the concrete ribs. Not sure if we will use the PVC when we get to the main footings, but I have 250 of these things cut and ready to go.
The rain washed off the concrete “crème” and left an exposed aggregate look. I kind of like it and I think the shotcrete will stick to it well. Another “day” done.
I still haven’t seen the bill (or paid anything). In order to get a reasonable bid on this unusually complicated project, I had to get the bid based on “volume and materials”. I thought that was safer than “time and materials” because at least the volumes were calculated beforehand. Basically, I agreed on the cost per cubic yard for forming and pouring as well as the cost, per ton of rebar, for placing and tying the rebar. But I do not yet know what he will charge for the materials (such as the wood, rebar, and concrete) or the total cost of the pump truck, or how the over-orders of material will affect the bill. I am a tiny bit nervous about that.
Today was day 2 of the footings. We needed to level them and get the rebar in and ready for inspection. Here is the time-lapse video for the day;
I figured we would be able to get it done in just a few hours, so I booked the inspector to come during his next available slot, 2 days away. They Dysert Concrete guys usually work in a bigger town near by and didn’t realize that my township only has one inspector and that he only inspects for 6 hours a week. They assumed they could finish the rebar, call in the inspector and still pour the same day. Fortunately, we talked about the plan at the start of the day. Some quick phone calls were made to stop the concrete trucks and then they got to work unloading the rebar and other equipment from the truck. Doug Dysert didn’t make it out today (so I still haven’t been able to give him a check or see a bill). Baudilio, who I worked with the most on Friday, returned, but with two new guys; Don, a more experienced (20 year) veteran and Chris, the younger guy (9 years experience, but only one week with Dysert) who got the less pleasant jobs.
Bau got to work on adding stakes around the footings while Don got to calculating the volume for the next days pour (I wasn’t surprised that his number was half a yard higher than my computer model predicted). Chris, the new guy was unloading the truck. I was just standing around without much to do. So, I asked if I could use the motorized tamper. It was kind of fun, as long as I didn’t try to back up. I went around the “track” a few times until I felt like I was wasting time.
Talking to Doug on Friday and he mentioned that these motorized tampers are pretty expensive if you buy them new. He said that the motors don’t last long, but the base lasts forever. He always looks for an old one that doesn’t run, buys it cheap and then replaces the motor. Good as new for less than half the price.
Then the more experienced guys got to work leveling the footings using a rotary laser level and a sensor on a measuring rod. They set the rod on the top of the footing and the sensor beeps to indicate if it is higher or lower than the laser. Fast beeping meant they footing was too high and needed to be lowered until they got a steady tone. Slow beeping meant it was too low and needed to be raised. Either way, they would screw the forms to the stakes at the correct height and continue on to the next section.
While they were doing that, Chris was cutting “rebar chairs”. These keep the rebar at the right position in the concrete and out of the sand. I “helped” by suggesting that he could probably cut thru more than one at a time. I like to think I increased his productivity by 600% ;^) Again, without much real work to do, I tried to keep myself busy by distributing the rebar chairs around the site.
After the forms were leveled, there were some gaps under them, particularly where they had been lifted up by several inches. Again with nothing else to do, I got to work backfilling behind the forms with dirt so they concrete wouldn’t just leak out. It turned out that I had not back-filled nearly enough and Chris went around behind me and did a lot more.
Meanwhile, the other two guys finished leveling and switched to bending and placing rebar. They had brought a manual rebar bender/cutter, but never used it. Instead they used a concrete saw with a 12 inch grinding wheel for cutting (caution, that rebar is still hot for a long time after). All the bending was done “freehand” as needed. They did have a rebar tie gun that is 
supposed to make the job easier, and it probably did, when it wasn’t messing up, or running out of energy, and it sure used a lot of tie wire (several reels worth). I looked up the specific gun they were using and it costs $3,385 to $3,865 depending on the specific model.
Warning to anyone who wants to come out and help me: I think I will tie the rebar in the walls and ceiling with manual rebar tie hooks that use the little pre-cut and looped pieces of tie wire. I wonder if an 8 year old and a 10 year can handle that?
The #4 rebar is pretty easy to bend, but not very easy to “curve” into the right shape, especially once you mess up. I tried a few curves and decided I was hurting more than helping, so I stuck to the straight pieces with the simple bends.
The experience with free hand curving rebar was enough to convince me that such an approach would not be acceptable when I am working on the rebar for the vaults. I will look into getting the rebar “factory” curved, or else build some sort of jig out of stakes to try and come up with a more precise method.
B
efore heading out there, I had looked up the coordinates where the “concrete encased electrode” would be. This is basically using the rebar in the footing as an additional grounding rod. So I set that up, complete with the rebar grounding clamps.
Lastly, I helped position some tubes in the footings so that we will have bleed holes, holes for the radon pipes and an exit to the septic system later.
We were done in just over 4 hours.
Next up, inspection to check our work and then we can pour the concrete.
Basically, track is needed to hold steel studs in place. The studs hold the metal lath and the metal lath will catch the shotcrete and shape the walls.
