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.
The Video:
My time-lapse camera is pretty basic and has a manual focus. I had it set to 8ft instead of ∞. Easy mistake ;^). But here is the slightly out of focus video anyway.
The Story:
I was not able to be on site when the crew setup the formwork and rebar for the garage slab. When I did see it, I realized it would need to be redone. Engineering had been done by 2 different engineers… The first was the engineer that I had hired to do the entire project. He specified rebar every 24 inches across the slab. The engineer from SteelMaster specified 6×6 WWR (welded wire reinforcement). I decided to do both. The guys who assembled the footings were only looking at one of the drawings, so they just put down the WWR. In addition to adding rebar, I wanted to add a vapor barrier, rigid insulation and radiant floor pex also…
First, I waited for the plumbers to come and do their work roughing in the garage bathroom. While they were working, I removed the large sheets of welded wire reinforcing and bent 40 peices of repar to put into place. After the plumbers were done their work, I tried laying it all out myself. However, I soon realized that positioning 16×8 ft sheets of welded wire is really a two man job. I decided to phone a friend. Aaron was willing to give me a hand early Saturday morning.
We started by excavating away a couple inches of sand in the areas where we planned to place the rigid insulation. At nearly 27$ per sheet, I didn’t want to insulate the whole slab, but I did want warmer feet in the bathroom and workshop areas.
We cut and laid the insulation carefully around the plumbing for the bathroom. And then in an “L” shape where my workbench would be…
Then we unrolled a 20ft wide sheet of 6mil poly to use as a vapor barrier under the slab and under the footing all the way around. Here, we are lifting the rebar in the footing to get the plastic underneath it.
The poly sheet was 20’ wide, so we had to do this in two overlapping pieces… Which Aaron taped together.
Initially, we had rebar chairs down the middle, but they were too tall so we had to remove them later.
I measured out and marked the 24 inch intervals for the rebar using surveyors paint.
Then we laid the rebar, using small bits of insulation as spacers. We put the 6×6 WWR on top of that.
Lastly, I brought out some pex pipe for future radiant floor heating… The pex was much longer than I needed for the bathroom, so I made a last minute decision to swing a loop out past my workbench… I secured it to the Welded Wire Reinforcement ever few feet.
The last thing that needed fixing was the wooden board that had been put in place as a keyway for the quonset hut. It had been installed too shallow and had been put in the wrong place (even though I had clearly marked where it should go). We decided to let the experts fix that mistake on the day of the pour.
The Mistakes
- Perhaps I should have excavated a bit more before placing the rigid insulation. It seemed OK at the time, but after adding spacers, rebar, WWR and radiant tubing, I wished I had it an inch deeper.
- I may regret adding the pex loop thru the shop… It may end up making it difficult for me to heat that bathroom adequately without also wasting heat in the shop.
- I only tied off the pex every few feet. But later, when we added the concrete, many sections floated to the surface. The crew pushed it back down again, but then later they didn’t want to cross cut the back half of the shop. Of course, cracks formed along where the PEX tube was too close to the surface.
The Video
You can find the video here:
The Story
The day started early, with the site mostly staked from the previous day (that video was not very interesting, so I won’t bother posting it)…
But we still needed to place a few more stakes, so as the morning fog cleared, Sherri and I finished what we had started.
We were in a rush, so our precision was not the best, but the footings are 2 ft wide and the wall is only 6 inches wide, so we just wanted to get things within an inch or so (further fudging happened when the forms were actually placed, I hope it all works out)…
The guys from Dysert Concrete arrived and started working on forming the garage while we finished up the stakes on the south side of the house.
The garage perimeter required about 200 linear feet of boards. The plan is to pour the garage footing and floor at once (sometimes called a thickened edge slab). The perimeter is 2 ft thick and 18 inches deep (shallow frost protected footings), but the middle is only a 4 inch thick slab. So we would need to dig trenches around the perimeter and then also backfill and tamp down the middle.
The rest of the house looks curvy, but actually it only needed 350 ft of curved boards and 400 ft of straight boards. They used 2x12s for the straight boards and the flexible ones are half inch thick lap siding. Actually, it seems like modern builders only use lap siding for curved forms, never for actual siding. The bedroom side of the house is mostly straight boards, with curves on the end and back (against the earth).
People assume the curves add to the cost, but actually, the lap siding costs much less than the 2x12s and the curved walls resist the earth loads better, allowing me to use 1/3rd the thickness and less reinforcement.
These are just the footings. Basically, the walls will sit on them and it will help to distribute the loads so the house doesn’t sink into the sand. They will end up one foot below the floor and will never be seen in the final house, so the exact angles and curves don’t really matter that much. So, when the inside radius of the bedroom apse was just too tight to curve the lap siding board without breaking it, we just went with piecewise linear…
As they started leveling the tops of the footings, it became clear that we would need bring up the ground level a little, especially on the bedroom wing side of the house… I used my skidsteer to dump some sand near the right places.
The next day, they continued with leveling the forms and moving sand around to meet it. I actually needed to get a bit more sand for them. They use a builders level to set the boards to the right height and then screw them to the stakes. After the boards are screwed to the outside stakes, they can remove the inside ones. Then they push sand up against the outside of the forms to help resist the lateral force of the concrete. It worked in most areas, but it later became clear that they should have used more stakes in some areas to prevent the concrete from moving the boards.
After leveling, they ran the tamper thru the area to pack it all down so it won’t settle later… Then they set the rebar chairs (that will keep the rebar out of the dirt). At this point, we had an issue because they had brought 6 inch rebar chairs because they assumed I would want the rebar in the middle of the footing. But since most of the tension would be in bottom of the footing, I needed them to push those chairs half way into the ground.
Eventually, they cut, curved and placed about 2000 ft of rebar. Actually, I had ordered much more rebar than I needed because I figured I would use it eventually. I was very happy to be able to use my SkidSteer to unload the two large bundles from the top of the truck. I am sure Doug’s guys were also happy that they didn’t have to unload it.
The Mistakes…
As per usual, I am sure I made a number of mistakes. Many will become known as I move ahead with the project, but I know of at least a couple already.
- I was busy working that day. I was short on vacation days and only took half the first day off and none of the second day. This means I couldn’t guide the crew. Instead, they relied on my stakes. I had placed the stakes fairly carefully, hopefully within an inch or so of where they should end up, but the guys simply measured off the stakes and cut boards without concern about matching lengths or square angles. If I had walked with them, I could have said “this board is 6’9” long and so is the one opposite…” It would have resulted in a more accurate footing… On the other hand, the footing will be buried and doesn’t need to be perfect to distribute the load adequately. There was actually a 3rd day, but I couldn’t make it out to the property at all that day and they really didn’t understand what was needed for the garage footing, to the point that we had to redo it (fortunately, I did not have to pay by the hour).
- My plans were changed by an outside force and I didn’t properly adjust my 3D model or work thru all the ramifications. The change started when the basement was dug and we excavated a wider area than I expected. This caused the inspector to require that I added those pilasters to help support the footings that spanned the backfill. We also made a change so that the garage floor and footings were poured at once, and therefore the top of the garage footing was the same level as the final floor. And since I needed the footing to sit on top of the basement wall, I put the mud room footings at the higher level all the way across from the garage to where they sit on the pilasters. I thought about how this would affect the concrete rib that will sit on that footing (I will need it to be a foot shorter than the others.) but forgot that it would also affect how the floor is poured and would also complicate how I insulate that footing. Oh well, I will deal with that when I get to that point.
