Quonset Hut Steel
There were a number of issues that delayed starting on the Quonset hut, including two extra weeks for delivery and I had to travel to Europe for a two week business trip… but eventually all the plans were in place and we had a nice weekend forecast (for late October), so my parents and sister (Bonnie) came down from Canada to help out.
The Video:
You can find the full video here:
This all happened about a month ago… But it takes a while for me to find the time to put these videos and blogs together… At the time, I made a short and quick video and posted it to Facebook. Generally, the facebook posts are much closer to real time and are much much shorter than the bog posts. If you are interested, you can like us on Facebook (click over here in the right hand side è)
This is the short video that I posted on Facebook a month ago…
The Numbers:
Each arch is made up of 7 pieces of steel bolted together with half inch bolts. Each arch section ends up weighing ~240 lbs. This portion of the building is my garage/workshop and will eventually have 20 arches and be 30 ft wide and ~40 ft long. For now, I have only put up 11 arch sections because I plan to build some forms for casting concrete ribs in the back and then roll them to the front where a crane can lift them up and move them into place.
The garage steel came on 1 pallet weighing about 4800 lbs. It included 2 buckets and 2 boxes containing about ~5000 pairs of nuts and bolts. The cost for the steel/nuts&bolts/engineering/delivery was $7200.
To assemble the arches, I used the help of friends and family… No one who helped had ever done anything like it before. The first Saturday, I had my parents and sister to help for nearly 12 hours, pre-dawn to dark. We got up 6 arches, which means it took an average of about 8 man hours per arch. Actually, the second arch took 3 hours and 40 minutes, which is about 14.66 man hours… And the 6th arch took 1.5 hours or 6 man hours. That is a decent learning curve. The second Saturday is harder to calculate because I had different people who came at different times for different numbers of hours. The first arch was done by 3 people and some time was lost giving tours to arriving friends, etc. but we were starting on the second arch by 2 hours and 10 minutes later, which is 6.5 man hours. The 9th arch (the last one that we had a full crew for) took 7 guys only 35 minutes, which is just over 4 man hours.
In total, my friends and family gave me 94 man hours over those two Saturdays. If I had to pay a moderate 20$/hour, that would have cost me $1880 in labor. I never got a quote to get the building professionally assembled, so I am not sure how that compares. However much I saved, I really appreciated the help and I hope they had some fun doing it.
The Mistakes:
- There was that one piece that we didn’t overlap in the right direction… It should be OK in the end because the seam is almost at the top and we plan to cover the structure in concrete anyway.
- I was not able to get the width down to 24 inches each for the arches… I was always half an inch over. I don’t think it will affect the strength much and the extra bit was balanced on both sides, so the building is straight. The biggest problem is that the structure is already about 6” longer than it should be. I don’t yet know how I will handle it when I add the remaining arch segments and get to the end of the slab… I don’t think I want to add an extra footing to move the front wall out 8 inches. The other options include not using the last arch, or perhaps cutting the last arch… I won’t really know how big of a mistake that was until the garage is complete.
Actually, I think this drawing from the manual is a little wrong… The text says over and over again that the 24″ should be bolt hole center to bolt hole center…
The Story:
The assembly actually began on Friday. I knew we had a lot of hours ahead of us, so I asked my friend Aaron to come out and help me get 4 ribs together. It took us about an hour to get the first couple together. We timed the second couple and managed to get down to 17 minutes for each of those.
We arrived before dawn and were prepared to raise the first arch soon after sunrise. The arches went up pretty easy, for a 240lb arch of 20 gage steel. The biggest issue was really how flexible they were…
The first one had nothing to lean it against, so we braced it with wood and rope and then hurried to get the second one up to stiffen the assembly. The second arch was very difficult. I thought it was going to collapse at one point and I was seriously questioning my plan to erect this structure without any professional help.
However, as we bolted the two arches together, things started firming up. This was good because the wind started to pick up. You can see things start to move and shake in the video. I spent a lot of time stressing about the width of the arches, but it was really the wind that made me push on to get a few more arches up to increase the stiffness of the structure. The instructions said to assemble 4 sections and then tweak the building, so we moved ahead.
The 3rd and 4th sections went up pretty easily. We had a pretty good rhythm for bolting things together and it helped that the sun was out and things were warming up nicely. We now had almost a ton of steel up and the wind was not flexing it as much.
After the 4th arch, my father and I were fighting with the steel to try and get the width down to 24 inches… We just could not compress it that far. The depth was correct, and that made no sense to me.
Since I was too distracted to provide any guidance, the ladies took the initiative and started assembling the 5th arch on their own. Unfortunately, they assumed all the steel pieces were the same… which would have been right for a true Quonset, but this was an “S-type” made up of two different radius pieces. It was clearly curving too much and Bonnie realized something was wrong. She interrupted my stressing and said, “Hey are there two different radius pieces here?” Oops, I felt bad for letting them waste their time. I took a moment to explain the two different curvatures and how the pieces went together and then they got back to work.
I eventually accepted the slightly greater than 24 inch width and started drilling holes and bolting down the arches. Perhaps this was a big mistake, but I couldn’t see any other way forward.
The view from the top was nice though…
The 5th arch went up very easily and the ladies (now expert) began to assemble the 6th arch while the men bolted the 5th to the 4th. Sherri and the boys arrived just as we were getting ready to raise the 6th arch. It had been tough for me to manage all three ropes during the pull, so I was glad to have Sherri up there to help. After the 6th, it was clear that the day was ending and we wouldn’t necessarily have time to get another arch fully in place and properly secured before dark… We decided not to try and raise any more ribs that day. Instead, we just prepped for the next Saturday.
My family went home to Canada and I spent the next week trying to get enough local friends together to help me put up a few more arches before winter really set in… Many of my friends had prior commitments or were working, etc. Some could come for earlier hours, some could come later, Some could only come on Sunday instead of Saturday, etc. I was mostly concerned about not having enough guys there at one time to actually pull up the ribs. However, by Thursday, I did get enough to sign up for a fun workday in the freezing cold.
On Saturday morning, Aaron and Don showed up first. Since we didn’t have enough people to pull a full arch into place, we decided to try the “piece by piece” method. It actually worked pretty well, although it was a bit slower than the other method and we did make one overlap mistake (probably because we were rushing).
Then more friends arrived. Carl and his son Kent came with Doug, so we had an instant crew. A while later, my brother-in-law, John, arrived. Getting the arches into position with that many guys was pretty easy and then we had several pairs working on bolting things all together… The biggest bottle neck was waiting for me to anchor the arches to the concrete at the end. My previous approach had been to work bolting the ribs together, and then work on anchoring the previous arch (we kept the current arch loose so the next one could be fit over it easier). However, with so many guys bolting the arches together, it made much more sense for me to start anchoring the previous rib as soon as the new rib was up, but I still couldn’t finish before the guys got the rest of the bolts in place. We got pretty fast by the end of the day.
Next, I will need to grout the trench. The building is attached to the ground, but doesn’t have real strength until the feet are fixed in place so they can’t lean in or out.
The Video:
I thought this video was more interesting than some of the recent ones. Hopefully you enjoy it also.
The Story:
I got there a bit early and got to sweeping off my newly poured concrete, but I was really doing some last minute thinking about where the well should go. Factors to consider range from ease of hookup now, to constructing around it and eventually living with it.
The well drilling crew from Cribley Well Drilling arrived and we settled on a location they could access. They actually wanted to put it about 10 or 15 feet out from the house, but it would have made it difficult later as I tried to get equipment and trucks around my house… I had originally wanted it further around the side of the house (which is why the camera angle had been set up that way), but they didn’t think they could drive the truck over there because of the soft sand, and if they did, the well would have been too far from the building and in the way later. Eventually, they agreed to get it as close as they could to the front of the house. The main constraint was needing room for the large drill fluid recycling tank behind the well head. The final location will end up behind a retaining wall, out of the way.
I dug to level the ground for this tank and they filled it with water from the second truck.
The drill bit was a 9 inch tricone bit. As an engineer, I have worked on computer simulations for these for my companies “oil and gas” clients, so I know that these are designed for crushing rock and stone. As the bit turns, the three roller “cones” rotate to break-up and scrape away rock. Water is pumped in thru the shaft, both to cool the bit and to push the debris out the hole. You can find an animation here… It was definitely overkill for drilling in my soft sand, but it got the job done.
They started things off without water, just to locate the hole… But then they pulled the bit up again and added a spout collar to direct the drill fluid (water with a bit of bentonite clay mixed in) into the recycle tank. Sand and gravel settles out in the first section of the tank and the cleaner water/clay mixture flows over to the other end of the tank where a hose sucks it back into the truck and thru the drill shaft and down into the well again. If they didn’t recycle the water, it would take a large swimming pool worth and would make a huge mess. Every now and then they would need to dig (or dump) the sediment out of the tank.
After they drill the first piece (with the bit on the end) in to the ground, it is time to add an extension to the shaft. The $600,000 Versa-Drill rig is designed and built for streamlining this task.
It comes equipped with two hydraulically activated wrenches. First, the one at the bottom comes out of the back of the truck to hold the lower portion of the shaft still. The operator runs the drill backwards for a moment to loosen the end piece and then pulls back the “wrench”.
Then they raise the drill up to the top of the mast. The rig also has a carousel with 15 extensions (capable of drilling 300 ft with what they brought, but they can bring additional shafts if necessary). The carousel rotates the next 20ft shaft section into position and the rig screws its self in loosely. The second hydraulically operated “wrench” moves into place to hold the new shaft section still while the drill tightens into it. Then the new shaft is moved into place above the previous piece.
The lower end is threaded in with the shaft below it held in place by the lower hydraulic wrench… and the rig can drill the next 20 ft down. This process was repeated 20ft at a time, over and over. See the video.
On my site, it was nothing but sand for the first 116 ft. Then they hit gravel and it made a lot of noise… Enough to bring me out of my mobile office to see what was going on. That layer only lasted about 4 ft and they were back to sand. My neighbor, who lives higher on the hill, came to check it out and told us that he hit water after only 117 ft. Actually, the same guy who drilled my well had also done the neighbors, but with an older version of the drill rig. He said that the water table is definitely not flat.
My well didn’t reach “water bearing fines” until about 185 ft… At nearly 16$ per ft, just for drilling, that difference adds up. The guys from Cribley joked that they wanted to drill further to help pay off their new six hundred thousand dollar rig (yes, he mentioned that price several times and that Obama was letting him write it all off in one year)… But they stopped at 186ft.
The Versa-Drill V-100NG drilling rig comes equipped with 500/200 air, 3×4 centrifugal mud pump, 15 rod carousel (3½” x 20″, 9GPM water injection, built in 2″ Bowie grouter, 12K winches with job booms, hose reel, and mounted on a 2014 Peterbilt 340 6×6.
With the water table reached, they began the process of pulling out the drill, piece by piece, back on to the carousel. It was pretty much the inverse of the previous process, but went much more quickly.
The next step was inserting PVC casing into the well to keep it from collapsing. The first piece, the well intake, was special with perforations to let the water in… The rest were just 6” PVC tubes. They glued one into the next and lowered it down, repeat.
Since the 6 inch tubes were dropped into a 9 inch hole, there was still some space around the outside. Leaving this open would let sand fall down the gap and clog the well tip. To prevent this, they inserted a flexible 1” white tube into that space. Like before, they put down 20′ at a time and just pushed (without glue) one section into the next. They pushed it down to just above the water bearing layer. Actually, they did it so fast, the time-lapse camera didn’t really catch it. Once it was ready to go, they started mixing bentonite clay into a slurry and pumping it down into the well (at 35$ per bag, you can count them in the video, I didn’t want to). As they did so, they pulled up the white tube. This effectively filled the gap around the pipe with clay that would hold the pipe in place without letting water flow around it or sand get down into the water bearing fines…
Done drilling, it was time to clean up the equipment and pack up…
Overall, they ended up digging nearly 40% deeper than the 135ft that I had estimated. That increased my cost a couple thousand dollars over the initial estimate (but they have not set the bill yet and it has been over a month). On the plus side, they estimated my well was producing about 50 gallons per minute, which is quite a bit more than the 18 g/m pump that I planned to install. That means I will have more water than I need, which is a good thing. Pumping well water is also much cheaper than city water. At current electric rates, I will pay about 25¢ per 1000 gallons. My current rate for city water/sewer is about ~8$/thousand gallons. If we used the 400 gallons per day that the standard American family uses, the well drilling should pay itself off in a little over 5 years. That swells to 16 years if I include paying off the septic field (which also went about 30% over budget).
They will send a different crew to dig a trench and run water pipes to my mechanical room. A third crew will eventually install the pump and pressure tank after my mechanical room floor is poured. That will need to wait for spring.
The Mistakes:
I don’t know if I made any here yet. It probably helped that I had experts do the actual work. But if I find out about any later, I will come back and add it here. ;^)
The only think I can think of was that after the job was over, there was a lot of bentonite laying on the ground in the area… It holds the water well and stayed annoyingly squishy for days after the rain passed. I knew it would be a drainage barrier, so I didn’t want to bury it in place… Instead I decided to spread it out (with the skid-steer), thinking that might even improve the properties of my surrounding sand… However, a little of that stuff goes a long way and even spread out, it just made the sand squishy and more difficult to deal with. I should have just scooped it all up and saved it for later.
The Video:
The Story:
These things usually start early in the morning… This morning, we were all ready to get these footings poured without any of the usual last minute running around. Three concrete mixing trucks were waiting at the bottom of the drive way as a dozen guys from Dysert Concrete arrived. The concrete pump truck arrived and while it setup, the guys were walking around and scratching their heads about my strange layout. Some were even taking pictures with their cell phones.
I showed some of the guys where the garage formwork had been done incorrectly and they started figuring out what to do. I was nervous because the first few guys clearly had no idea how to mount the groove form… But then a guy showed up who clearly knew what he was doing and took over organizing that work while some of the other guys got to filling the other forms with concrete.
The concrete mixer trucks dump their concrete into the back of the pump truck. The pump truck comes equipped with powerful pumps that can push the heavy concrete thru its 135 ft boom. The operator has a remote control box and walks around with a few of the of the concrete guys to control the movement of the boom and the flow rate of the concrete while they guide the end of the pipe along the form. It is quite something to hear that concrete falling down thru the pipe. For a big job like this, the pump truck really is worth the money. The alternative would have been trying to position the mix trucks around the site and push or wheelbarrow the concrete to the inner parts of the forms…
Initially, they overfilled the forms. The thin lap siding formwork was not strong enough and started to give way and lean out. I guess there were not enough stakes in the soft sand to hold back that much pressure. And after that, they filled the forms only half way and gave it some time to stiffen up a bit before coming back for a second pass. After the forms are filled up, they simply screed them off. It was amazing how the weight of the concrete pushed out even the 2×12 boards.
Meanwhile, the larger group were still working to properly finish the groove forms for the garage.
By the time the form for the garage was ready, they had already finished pouring the footings for the rest of the house. They started by filling the perimeter of the garage footing. They gave that a little bit of time to stiffen up because this was 18 inches thick and even more likely to blow out. While they waited, they pushed in vertical pieces of rebar along the middle of the floor to mark the floor slope.
Eventually, they started filling up the slab area, but quickly ran out of concrete. Another whole truck arrived and they dumped it out, but it didn’t go too far either. Along the way, they were screeding off the surface with long poles and leveling the concrete against the side of the forms and the rebar pegs in the middle. On the right side of the below picture, you can see the power screed that they used.
I noticed a slight bulge were my radiant floor pex tubes went under the concrete. I pointed it out and they said that it must be floating up. They said I should have tied it down every 8 inches… I thought that they (as experienced professionals) should probably have checked that before starting. Anyway, since we were waiting for the next concrete delivery to come anyway, they just gave the concrete a little time to stiffen and then pushed the pipe under (using long sticks) and pulled concrete (screeded) over it. I was still very nervous that it was still too close to the surface, but they told me it would be fine. I didn’t think until later that I could have put a piece of that 6×6 inch welded Wire reinforcement over the pex pipe to make sure that it stayed down…
Another truck load of concrete arrived and was pumped out. This time my concern was that the 6×6 WWR (Welded Wire Reinforcement) had been stamped down too much, especially at the front of the garage. Like the rebar, this welded wire reinforcement needs to be fully encased within the concrete to do its job. It doesn’t do much if it is trampled down under the concrete. I had been pestering the guys to try to pull up WWR elsewhere, and they made some halfhearted attempts upon each request, but at the front of the garage, where the slab sloped to the full 18 inches thick, it was so trampled down that I concluded it would be hopeless to ask them to pull it up… Instead, I waited until they got the got concrete in, and then I brought over two more big pieces of WWR and laid them on top before they guys had a chance to screed things over… Hopefully, these additional pieces stayed within a few inches of the surface where they could do their jobs.
With only one little corner left to go, they sent the pump truck home and we waited for the last concrete mixer truck. Most of the crew left also, except for two guys who were going to hang around and do the finish work on the slab.
After the last couple yards of concrete were in place, the senior guy used a power trowel to work the surface. The younger guy got busy working on removing the wood that held the groove form in place. Since things were now setting up quickly, my family and I rushed to press our hands into the stiffening concrete.
They took the power trowel over the surface 4 separate times and did a pretty good job there and on visible edges of the slab.
All in all, the footings and garage floor took 78 yards of concrete. The guys put down about 1300 lbs of rebar in the footings and I added another 530 lbs in the slab floor. That is just shy of a full ton, not including the fourteen 16×8 sheets of 6×6” WWR.
They came back the next day to remove the forms and cut grooves in the concrete… However, they didn’t want to cut up in the area where the radiant pex tubing had floated near the surface.
Mistakes:
On the whole, the footings turned out pretty well, and I appreciate that Dysert concrete was even willing to take on this job (many other companies didn’t even call me back after seeing the plans).
However, as a first time General Contractor, I made some mistakes here (just like every other phase of construction).
- I should have checked those forms better. As the rule of thumb goes, “put as many stakes as you think you need, and then add a couple more.” We didn’t have enough stakes in many places, especially on the bedroom side where the sand is softest. The bulges are a bit ugly, and they wasted concrete (more volume than needed). In one spot where the form leaned out, it actually affected the surface level of the footing and may give me a bit of a headache later… Oh well, at least these footings will be buried and never seen again. They don’t need to be pretty to do their jobs well.
- I did ask one or two guys if the pex tube that I placed looked right, and they just gave me a nod and a grunt… I should have got someone to check my work more closely. Then they would have seen my mistake (not tying them often enough). Things would have been more secure and I could have properly cut the slab to prevent cracks… As it is, I have 3 long (thin) cracks across the uncut portion of my slab…
- I should have complained about the level for the grove form. I saw that the east side sagged a bit in the middle, but I thought it would float up or be taken care of some other way… I didn’t say anything and now I need to deal with water pooling in that area. It won’t matter when I am finished the Quonset and grout the groove, but in the meantime, it is annoying. If that water freezes, it could cause damage. It could also rust the bottom of the Quonset steel before it is grouted…
Generally speaking, you need to speak up about concerns and get them addressed before the concrete gets poured… It is too easy to get swept up in the frenzy when there are so many things happening on the site.
This all happened about a month ago… But it takes a while for me to find the time to put these videos and blogs together… At the time, I made a short and quick video and posted it to Facebook. Generally, the facebook posts are much closer to real time and are much much shorter than the bog posts. If you are interested, you can like us on Facebook (click over here in the right hand side è)
The garage steel came on 1 pallet weighing about 4800 lbs. It included 2 buckets and 2 boxes containing about ~5000 pairs of nuts and bolts. The cost for the steel/nuts&bolts/engineering/delivery was $7200.
