concrete progress. and then a setback.

10Sep08
The concrete truck backed up to our house last Thursday.

The concrete truck backed up to our house last Thursday.

This post is brought to you by a couple of broken ribs. Unfortunately. I’ve been trying to find time to write about our concrete pour last Thursday. But things have been really crazy, and I haven’t had a chance. This morning, we were supposed to be pouring the second half of the floor, but our concrete guy called last night at 9:00 p.m., just as we were finishing up all the preparations for the next pour, and said that he’d broken some ribs, and wouldn’t be able to pour. A bit of a disappointment, but probably not as disappointing as being stuck with broken ribs. So, because of the broken ribs, I have a little bit of time this morning to write a blog entry. That seems to be the only silver lining involved.

We don’t hire people to do very much for us. That’s just the way we are. Luke fixes our cars. (I pretend that I’d like to learn something about fixing cars, but after handing him a few wrenches, I get bored and wander back inside.) We made our own wedding rings, we’re building our own house, doing our own plumbing & electrical, along with nearly every other aspect of the building project. When the hard drive on the computer died, we used the internet to get instructions on how to do surgery on a laptop. We don’t make much money at this point, but we get by because we’re willing & able to do a lot of stuff for ourselves. And we’re willing to fix things & keep our old things running. (Thus, our 14 year-old car and our 25 year old truck. We’d love to replace them, but we can’t afford to pay cash, so we don’t.)

But I firmly believe that the secret to good craftsmanship & doing things WELL is knowing your own limits. And, for better or worse, I think that if something isn’t worth doing well, then it’s probably not worth doing. I pay someone to cut my hair because, really– I don’t have a clue. We have an accountant do our taxes because it is cheaper than the marriage counseling that would otherwise be necessary. And medical care really isn’t a do-it-yourself activity. We hired Curt to help us frame our kitchen, because it was a complicated framing job–plus we wanted it done well AND done during this decade. So, when it came time to pour a concrete floor in the old portion of the house, we looked around for an expert. We’ve poured a lot of concrete ourselves, but we’ve never made beautifully finished concrete. And we wanted BEAUTIFULLY finished concrete. The smoother the better.

So, we asked Dick to do it. He’s an old friend of Luke’s family, and he’s been in the concrete business for a long time. He’s done a lot of finished floors. He’s quitting the business, but he agreed to come & help us, provided that we acted as the crew. We had been planning to “hire someone properly.” When I say ” hire someone properly” I mean that we pay them with real money to come in and do what they do best, while we sit back with a nice beer while other people sweat about all the details. But Dick doesn’t have a crew anymore, and I guess we were lured by the idea of getting a professional cheaply, because we wouldn’t have to pay for the crew. We’ve never YET sat back & been pampered, so why start now? So there we were last Thursday, schlepping heavy wheelbarrows of concrete around the house, following Dick’s orders, and being happy that this long-awaited job was finally getting done.

Dick elected to pour the floor in two parts, to make sure that it wasn’t too big a job for a novice crew and only one guy who knows what he’s doing when it comes to the finishing. We will someday have a structural wall running down the middle of the house, so we’ll be able to hide the cold joint. This was definitely the right decision, because there’s no way that he could have finished the whole floor as beautifully as he did if he’d had to do the whole thing in one day. And, like I said, our main objective here was to have it SMOOTH and BEAUTIFUL. I guess this makes me a modernist, but I want my concrete to look like concrete. (Only smoother and more beautiful than your average concrete.) I don’t want to cut it up into little squares and try to make it look like tile. If I wanted tile, I’d install tile. If I wanted stone, I’d install stone. I want my materials to be honest about who (or what) they are.

Concrete is a funny substance… and a funny business to be in. On the one hand, it involves back-breaking labor, and lots of really dry alligator skin. And on the other hand, it takes real skill combined with lots of experience to do a good job with the highly-finished stuff. Concrete has become a really trendy substance, largely because of its versatility & longevity, and there are lots of boutique businesses out there, selling value-added concrete work. But watching Dick out there on his skates atop some really green concrete, troweling it smooth for the third time, I could really see why he’s chosen to get out of the concrete business. It’s damn hard work, and probably is often thankless work. Easy to screw up, and really, really hard to fix once it has cured. He did a nearly-flawless job, which is about the best we could have hoped for. Now we just have to hope that he’ll heal up from his fall, and we’ll be able to convince him to do a fabulous job on the second half.

Sorry I don’t have any good pictures of the floor. Dick had us block all the windows with plywood, so that we wouldn’t get any hot spots that would cause uneven curing. Since we’re pouring the floor long after the house was built, we’ve got nearly-ideal conditions for controlling the curing process. But it means that the curing is happening in a hushed and darkened room. Visitors who want to see our floor, can be ushered in as if to a hospital room, where the patient is recovering from a high fever.

Oh, and by the way, it’s concrete. Not cement. Sorry if I get a little huffy about that– it’s an architect thing. They train you to get all sensitive calling concrete “‘cement.” (They do this by ridiculing you, so that you’ll learn that you sound uneducated if you use the wrong term. I think I’m glad I’m done with architecture school.) Cement is an ingredient in concrete. The more technical term is “Portland cement,” and concrete generally consist of cement, an aggregate such as gravel plus sand, and water. Nowadays, they are adding fly ash to concrete as well. Fly ash is a waste product from coal-fired power plants that would otherwise end up in the landfill. But clever people in labs have figured out that if you add it to concrete, you can reduce the amount of cement needed. Since cement is a very energy-intensive product with a very high-carbon footprint, the use of fly ash lowers the negative environmental impact of the concrete. Fly ash also increases the strength of the concrete, and creates a concrete that shrinks less, creating a more durable concrete product. High volumes of fly ash cause the concrete to reach its engineered strength more slowly, so that has to be taken into consideration when structural concrete is being used in conjunction with tight construction schedules. (Did I get that right, Carl?) After my comment that our local Redi-mix plant would probably laugh at me if I asked about fly ash, it turns out that they add it to all their concrete, unless you ask for yours sans-fly ash. So there you have it– maybe the world isn’t doomed after all, if they’re adding fly ash standard in provincial Center, Colorado.

In case you’re wondering, I am willing to call it a “cement mixer,” because the job of that little machine is to mix cement into the other ingredients in order to make concrete. But cement is cement, and concrete is cement plus some other stuff. Calling concrete “cement” is like saying “flour” when you’re really referring to bread.

The concrete conveyor being poked through the window. With an inch to spare.

The concrete conveyor being poked through the window. With an inch to spare.

Luke ready for the pour to begin.

Luke ready for the pour to begin.

Long view of the floor were about to pour.

Long view of the floor we're about to pour.

Dick on skates, finishing the floor.

Dick on skates, finishing the floor.

Saw cutting our new concrete floor.

Saw cutting our new concrete floor.

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7 Responses to “concrete progress. and then a setback.”

  1. And you have a floor! Quite the art… I’m not sure I’m up to it.

  2. 2 Carol Lenger

    I’m not sure where my comment to you went (maybe just to your email). Oh well, I said I hope I’m considered one of the 6, since I absolutely LOVE your blog! I feel like I’m learning a lot about you and Luke, usually get a few chuckles from it… oh, and yes, keep track of the progress of your home 🙂

  3. 3 Jen Helvig

    I just have to ask. Where did you put your handprints 🙂

  4. 4 millergeneral

    Please comment on construction details like the thinkness of the slab, type of concrete, fibered?,what you are doing to it afterwards like coloring?, um techy stuff.

  5. 5 lauracm

    To Millergeneral–

    It’s nominally a 4″ thick slab, and we were screeding off the new bottom plate we’d installed (actually an insulated box composed of 4 pieces of pressure treated 2x6s). The 4″ had gotten a little thin in a couple of places, so at the last minute, we furred up the screed guide (plate) by another 1/2″, because Luke was paranoid about the slab being too thin. Beneath the slab we’ve got 2″ of EPS rigid foam (the white stuff consisting of little beads). EPS is much more environmentally friendly, and is approved for under-slab applications, but not nearly as “tough” as the XPS stuff. At the last minute, we decided that the EPS wasn’t going to stand up to the wear & tear of wheelbarrows (etc.), so we added another inch of XPS foam on top (the solid, rigid stuff most commonly sold in bright pink or blue.) We’re insulation freaks, so we were happy to have the extra insulation, though not the extra $350 bill for the additional foam. We used standard remesh & tied Kitec heat lines to that. (Kitec is a pex-al-pex product… more on that in another post). The remesh sat on the very bottom of the slab, and Luke was nervous about the lack of useful reinforcement, while I was nervous that the heat lines are so close to the bottom of the slab, since they building science nerds have graphs the show that heat is better distributed to the room if the heat lines are in the upper portion of the slab. Nevertheless, it is standard construction practice to let that stuff lie on the bottom of the slab.

    We used standard 5-sack concerete mix, with some fly-ash in it. We decided against fiber because we didn’t want it showing up on the surface. Dick elected to pour it kind of wet for workability– 4 to 5 slump. Not being a concrete expert myself, we pretty much let Dick take control of that part. After much debate, we decided to saw-cut, despite the fact that it messes up our beautifully monolithic floor. We tried saw-cutting after about 3 days, but it was still too green, and pulled rocks up around the edge of the cuts. After about 4 days it was pretty much ready to cut. The saw cuts look pretty good– very thin & crisp. Eventually we’ll probably grout them in to lessen their visual impact.

    We don’t know yet what we’re going to do about coloring. That is the sort of decision that we’re very good at procrastinating on. Since the slab is already poured, we’ll have to do some sort of acid staining, if we do anything at all. We don’t want anything that is highly patterned, but most likely we’ll do s subtle acid-washed effect. We poured some “samples” out in the yard to test the acid staining on, though they look completely different than the actual slab, because they are not finished as well, and had completely different curing conditions.

    Anyway, hope that answers your questions. I was (am) planning to write a proper post about all of this stuff, but life seems to be a bit crazy these days, so this is my mini-post, in case I never get around to it…..

    Cheers,L.

  6. The floors look great. I’m so impressed and amazed at how much work you two are doing. And by the way, I like the blog’s new look! It’s very clean, letting your writing and photos stand out more.

  7. 7 Millergeneral

    Yeah, having the mesh on the bottom loses the reinforcement but it would be difficult to raise it up. You don’t need reinforcement for a non-foundation slab anyway. Nancy wonders about the hardness of the slab, concrete kills her feet at work. Short of a sprung floor on top, can’t see how you can avoid that. . . .


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