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Making sawdust.

Submitted by Ted on August 5, 2011

ShopThis week Eli and his team got a start on cutting wood for the house. I want to talk a bit about Eli's process, because it's very different than what I normally see done by builders. Rather than trucking raw materials to the site and cutting them to order on site, according to a blueprint provided by the architect, Eli (who is actually an architect among his other talents) has a really high-end CAD package he uses to prepare detailed drawings and cut lists.

This gives him a degree of precision in his plans that allows him to hand his cut lists off to his team, who pre-cut all the wood in the house and pre-assemble what they can in Eli's shop. This means that they can use tools that are set up on a nice flat concrete floor, and store the wood under the roof, and not haul stuff to the site that's going to have to be hauled to the dump afterwards.

I personally find this process both frightening and inspiring. Frightening because I would not have the confidence to go from a CAD drawing to cutting in a shop and shipping the results to the site. Inspiring, because this is exactly the right way to do a custom house: you design the whole thing in a piece of software that is intended to produce accurate cut lists. You have a crack team that can follow the cut lists and reliably produce a stack of pieces that really do fit together. You do as much work as you can in the shop. Then you load it all on a truck and bring it to the site.

Cut List DiagramThis is where we are in the process now. Eli calls it "making sawdust." Eli's crew is going to be cutting and assembling all next week. Nothing's leaving the shop. I think they may still be doing a bit of cutting the following week as well.

Another key aspect of this process is that as the pieces are cut and assembled, Eli's crew marks them, so that when the time comes to put them together on site, all the measuring is already done. So at that point all the team has to do is put the pieces together according to the markings.

Why do I think this is so cool? Because it's efficient. A well-built house, which I think everybody should get when they buy a new house, requires a lot of labor. But a lot of that labor is dead time where you're hunting for things, or switching tools, or whatever. Builders put a lot of thought into saving time on the site, but by doing things in the shop, the time savings are substantially more.

MarkupAlso, because Eli knows precisely how many pieces are going to go into the building, we started out with a clean bill of materials that we don't expect to have any substantial surprises on it, and Eli is also able to predict with some accuracy, based on his past experience with his team, just how much labor is going to be involved in assembling this.

Many builders brag about building to code minimum, as if that were an achievement, but really building codes are intended to enforce the absolute minimum level of quality, so that if your house was built to code, you at least don't have to worry that it's going to catch fire for no good reason or fall down in a minor windstorm. Many houses built to code minimum have flimsy walls, poor air quality, poor noise isolation, noisy floors, and crooked, flimsy fixtures. This saves money, and allows the builder to sell the house for a lower price, or take a higher profit. There's nothing wrong with either of these things, but if it were possible to make something better, wouldn't that be nice?

MarkupAndrea mentioned money in her previous post, and money is a real worry in a well-built house. The problem is that a home buyer has no real idea what actually went into the house that they are buying. They can't easily tell that they are getting a well-built house or one built to code minimum. Some things are obvious, but some things aren't until you've moved in. By using his CAD/CAM system, Eli is building our house for a very competitive per-square-foot price.

The result is that when this is done, we hope to have a well-built custom house without it being so expensive that if we should need to sell it, it would be impossible to recoup our costs. Anyway, that's the plan.

A question of cost

Submitted by Andrea on August 2, 2011

We're currently at the "Yikes!" stage of construction: we're getting a lot of big bills and high estimates and wondering just how expensive this house is going to wind up.

It's an interesting/alarming phase because we're now making decisions about the non-envelope parts of the house. We refused to cut corners on the windows and insulation, as well as other things that will affect energy performance. But now that the costs are mounting up ("Curse you, sloped and ledgy lot!"), we're looking around for corners to cut.

But which corners? Part of me says it's much more important to install a solar hot water system than it is to upgrade our kitchen cabinets. The cost difference between IKEA cabinets and the least expensive plywood cabinets is about $5,000, which would cover most of the cost for a solar hot water system. But IKEA cabinets are made from particle board and would therefore introduce formaldehyde into our nice tight envelope. Most people poo-pooh this dilemma, since particle board is ubiquitous, but lead paint and asbestos were once ubiquitous, and the evidence is mounting that no amount of formaldehyde is acceptable indoors.

[Added on 2011-08-18: It looks like cabinet manufacturers have backed off from adding urea formaldehyde in recent years, so I think we'll be OK with MDF doors after all.]

Note that I'm talking about the least expensive plywood cabinets, which still have doors and drawer faces made from particle board (the cabinet boxes are made from plywood). If we want to eliminate particle board altogether, the price doubles.

And then there's the question of countertops. Granite countertops are the (painfully hard) punching bags of the anti-consumerism crowd. No unsustainably-built McMansion is complete without granite countertops! If I were a real friend of the earth, I'd opt for tile countertops and virtuously accept the ugly grout lines. But I don't like grout lines, and I don't want to have to use nasty cleansers to keep them from mildewing up, plus it would crack under the abuse we and our guests would likely inflict upon it. I'm not opposed to formica, but I can't shake the image of the torn-out countertops in a dumpster 15 or 20 years from now when the next owner rips them out.

So I'm very tempted by granite, in spite of the high price and the high embodied energy. A better choice would be local soapstone or slate, but that's even more expensive. I could cut a different corner by using an asphalt-shingle roof rather than metal, but I'm once again haunted by the image of seeing it all torn up in a dumpster 15 years from now.

Fancy staircaseOne big and easy corner to cut would be the solar electric system. And we may just have to cut it, if the framing and insulation costs are as high as I expect them to be. We would at least put conduit and pipes in place, allowing us to add solar electricity and hot water down the road, but it's still embarrassing to say we chose expensive cabinets and countertops over renewable energy.

I've often joked that I'd gladly install counters made from plywood and contact paper. But we need to get a mortgage on this house as soon as it's complete, and I don't know how strict lenders are about cheesy hacks like that. Perhaps not at all.

One thing we boldly/foolishly did not skimp on is the staircase. I placed the order last week for a gorgeous curved staircase, custom made in Maine. We even paid extra for cherry wood rather than oak. Bad Andrea! But this will be the aesthetic centerpiece of the house, and we decided to just go for it. If we're lucky, maybe it will distract the appraiser from the contact-paper countertops.

[Added on 2011-08-18: Ted and I talked budget after I posted this (he had been leaving matters in my overly-conservative hands), and it looks like we're in better shape than I thought. We are still planning to go ahead with PV, solar hot water, and moderate upgrades to the finishes.]


Be prepared.

Submitted by Ted on July 22, 2011

Today's lesson: if you can do something today, do it today, because tomorrow your excavation guy may have time to do a bunch of work, and you'd like to fit into his schedule when he has the time. The problem with being your own general contractor is that it's your job to keep track of these issues. But in our case, Eli has been acting a little bit general-contractorly, and so I forgot that I'm still supposed to be keeping track of the schedule.

Really, when we decided to build the house ourselves, we weren't planning to pull in a lot of subcontractors, so in theory it was all going to be a lot easier, and we'd just call people when we needed them. When we pulled Eli in, that changed, because we decided to have him do a really substantial amount of work to get us under roof quickly. The problem with accelerated timeframes is that you really need to stay on top of the schedule or you'll wind up in a jam.

Today we wound up in a jam. Eli had suggested that I work on sealing the below-grade part of the garage foundation, but it was a little informal, and we were going to do it this week, and then it turned out that our electrical contractor's son, Sachary, had some time and could use a few bucks, so we wound up hiring him to do it. They were going to be on the site to set up the temporary electrical panel, so it sounded like a good plan.

The only thing is, Wayne, our excavation guy, was going to be on site to bury the electrical some more once the service was in. And since he was on site, he wanted to do some more work, because burying the electrical was a pretty minor job, and there's a ton of work to get done on the site. Wayne is one of those wise, experienced excavation guys who's dug a lot of foundations and really knows what he's doing, and doesn't mind offering his advice on how to do the earthwork right. As a consequence, he's in high demand, and has had a busy summer, despite the economic situation. But he's tried to do right by us by squeezing us in here and there, and he's succeeded.

The only trouble today was that we hadn't really thought about how it was going to make sense for Wayne to do some of the earthwork while he was on the site (actually I think Logan was doing most of the actual earth moving—Wayne was just there to make sure we were all clear on what the plan was). So we hadn't put in the low-voltage carrying pipe, and we hadn't put in the water supply pipe for the garage. We could have done those things any time in the past two and a half weeks—we just didn't think to do it, because I was hammering out a water channel further uphill, and Andrea managed to catch a nasty flu.

To add an extra complication, when we'd talked about how many sleeves to put through the garage wall, we had a miscommunication. We needed a 3" sleeve for the electrical, and a 2" sleeve for the low-voltage, and we'd talked about putting in another electrical conduit for the solar grid-tie (which I will explain in a separate post). We'd also talked about putting in a 2" sleeve for a water supply line for a hose bib on the garage, and maybe a utility sink in the garage. But then we figured out that we didn't need the sleeve for the grid-tie, because there was enough room in the 3" sleeve. So we deleted that, and in the process managed to lose track of the 2" water sleeve.

(BTW, for those who don't know, a sleeve is just a piece of pipe you run through the foundation wall before you pour the concrete. When the time comes to run services through the concrete, you have a convenient pipe in the concrete wall, and you can either join conduit to it, or just run a smaller pipe through it.)

So today, we needed to cut a hole in the concrete using a wet core drill. And we needed to run a 4" sleeve from the house to that hole, and through the hole. Fortunately Eli came by, and he knows everybody in town (I think literally), and his friend Dan, who is a plumber, just happened to be driving down Western Avenue when Eli called him, and Dan came to the rescue. Eli got one of his guys to rent a core drill, bring a bucket of water for the wet part, and a generator to power it. Once the hole was cut, Dan ran the pipe through it and up the hill to the place where it's going to enter the house. Andy, our electrical sub, ran the low-voltage conduit.

Anyway, I think that's what happened—by the time I got to the site at 6:30 this afternoon, all the work had been completed, and I didn't see who actually did it. Here's the sleeve sticking through the wall into the garage:

I was there to finish cutting a drainage channel through a bit of hard rock up at the top of the foundation. I've been working on this a couple of hours a day, maybe three or four days a week, for the past three weeks. Here's what it looks like:

I've actually removed a substantial amount of rock, but it looks pretty unimpressive. It'll be covered up in sand tomorrow. Sigh.

To PHPP and beyond

Submitted by Andrea on July 17, 2011

Our building site was relatively quiet last week. Concrete is curing, and our electrician set up the main panel and meter in anticipation of CVPS turning on the electricity this week. Ted and I also spoke with several solar installers to see about getting some PV panels at the roof ridge and also a solar hot water system. More on that as it unfolds.

The biggest news is that we recently partnered with Efficiency Vermont to pursue Passivhaus certification [follow the link to read their "About Us" page]. The cool part is that our house will be part of a research project to evaluate the suitability of Passivhaus construction for Vermont. They'll install monitoring equipment in our house and closely study its performance.

Peter Schneider, Efficiency Vermont's Passivhaus consultant, was particularly interested in studying our house because it has several unusual features: a pier foundation and partial shading. Vermont's abundance of sloping, ledgy lots makes pier foundation a tempting solution, and of course trees are rampant hereabouts. So hopefully we'll provide useful data for would-be Passivhausers in North America.

Peter was on vacation last week, so he hasn't gotten farther than the first few rounds of PHPP tweaking, but Marc helped pick up the slack. This will all probably change this week, and I'm probably jinxing things just by typing this, but so far it looks like we can pull off Passivhaus performance with the following general specs:

  • 11-7/8″ I-joist floor deck (16 oc), stuffed with dense-pack cellulose and with 4″ of polyiso underneath.
  • 9.5″ I-joist wall framing (24 oc) filled with dense-pack cellulose and with 4″ of exterior polyiso.
  • 24" roof joists, filled with dense-pack cellulose.
  • Schuco SI-82+ windows, which we ordered this week from European Architectural Supply in Lincoln, MA. The windows are PH-certified and made from uPVC. Yes yes, PVC is evil, but this is unplasticized PVC which is apparently a bit less evil. It's made without phthalates and can be recycled, at least in Europe. But hopefully the windows won't need recycling for a long long time.
  • Climatop Max and Climatop Ultra-N glass. The glass offered by Schuco is pretty darn impressive. For the south windows we upgraded to Climatop Max, which has a SHGC of 0.6, but for the rest of the house we went with the Climatop Ultra-N, which has an SHGC of 0.5. All the glass has a Ug of 0.105 (which PHPP callously rounds up to 0.11).
  • We haven't decided for sure on the HRV yet, but we'll probably either do the Zehnder ComfoAir 350 or the Paul by Zehnder Novus 300. The latter adds about $1,400 to the already formidable cost, but the efficiency is 93% as opposed to the ComfoAir's 84%, which would win us quite a bit within PHPP. Another knob to turn would be to add more polyiso under the floor or use larger I-joists — we'll hopefully do the cost-benefit analysis this week and reach a verdict.

It seems like the biggest advantage in our design is the ludicrously simple house shape. We're basically building a shoebox with a shed roof, which means there aren't many corners or thermal bridges undermining our envelope. Marc, Ben, and Eli already minimized thermal bridging before we decided to go for Passivhaus certification, so we're picking up a lot of PHPP points without having to change our plans.

We're waiting on a few more details, though, including some THERM data Peter is confirming with PHIUS. Hopefully that won't kick us back out of the ballpark, but as I said we still have some knobs left to turn.