Follow my progress as I build the first-ever net-zero home in Spring Green, Wisconsin and I’ll keep you up-to-date and send you Open House invites!
December 16: Everyone is welcome to stop by and have a look at Spring Green’s first net-zero super-insulated home. I’ll be there to show you around and explain anything you might be curious about. My POEM HOME is at 770 Westmor Street, one block north of the High School and on the same side of the street.
November 30-December 10: Framing is underway! The wall panels arrived from a factory up north, along with the roof trusses. A large flatbed truck off-loaded them onto a flat area I had the excavator prepare next to the curb.
My crew, brothers Pat and Jamie Rogers, immediately set to detaching the stacks from their shipping lumber. By noon, the crane arrived from Dodgeville and the first panel became airborne a half hour later. By 3 pm, all but the east wall was set and secured.
Most homes in our area are built on site, stick by stick. The promise of prefab homes has long been held out as “the future of home construction”. I’m not sure why it isn’t more commonplace. In my 32 years as a home designer I’ve only collaborated on two. But I decided it was a good bet for this house.
One reason is that my salesman at Tri-County Building Supply in Spring Green was experienced with it. Jim Barnicle became my partner in reviewing the shop drawings supplied by the factory to make sure they lined up with my blueprints. The idea is to think things through on paper instead of on-the-fly at the job site. I wanted to apply the principals of “advanced framing”—-using as few studs and headers as possible to reduce waste and structural redundancy while also providing more room for insulation. This protocol is promoted by building scientists and “green builders” like me but isn’t well known or well accepted.
Prefab homes—or in my case panelized components—are built in a climate controlled facility and are erected in days, not weeks. The wood isn’t exposed to the weather as long so it stays dryer and straighter. The factory is incentivized to minimize waste, and spares me the work of stacking, saving or dumpstering cutoffs. What’s the downside? The cost and energy to transport and erect the panels. Renting a crane is expensive. This one is $170/hour and it’s not always easy to stage a project for fast action. Sometimes, it idles.
The next day, my crew set the interior wall panels, finished the house shell and got the garage up. We called the crane off for the next day to fiddle around with details but brought it back the following day to set the roof trusses.
My plans call for a “double stud wall” and “raised heel trusses”. The exterior walls are 2×4 studs spaced 24” inches apart (instead of the usual 16”) with a matching 2×4 interior wall to create a 12” deep cavity for insulation. The roof structure is 24” deep, to accommodate up to 22” of insulation. The sheathing is 5/8” 5-ply plywood—a premium choice over the usual 1/2” OSB (oriented strand board). Thicker sheathing is stronger and less likely to bow across the wider spacing. Plywood is better than OSB at taking on and recovering from any water or vapor intrusion and is more airtight.
The idea is to go above and beyond code minimum for long-term energy-efficiency, durability and occupant safety. I specified an aggressive nailing pattern and other structural upgrades, based on the American Plywood Association’s protocol for wind-resistant construction. Their research shows that when homes are carefully constructed, they can withstand—with minimal damage—95% of tornadoes. This comprises EF-0, EF-1, and EF-2 tornadoes. We don’t exactly live in Tornado Alley, but most of us around here remember the EF-2 tornado that tore up homes and a wide swath through our beautiful Governor Dodge State Park in 2014. Here’s a map showing the incidence of EF-2 and stronger tornadoes.
Rough framing has got to be the most glorious stage of new home construction. Plans on paper become three-dimensional forms you can finally walk through and feel. Elevations sketched with nicely proportioned windows finally become picture-perfect views. Here’s sunset from the west bedroom (with pond).
November 5-9: We got a pretty good foundation pour, but there were a few rough spots. Carpenter Lew Lama used a grinder to smooth out the top of the wall for the sill plate and leveled a few areas with a cement patching compound called Rocktite.
Our next step was to lay down the vapor barrier. I selected Tu-Tuf #4, a sturdy, tear-resistant white polyethylene that handled easily. We sealed seams and penetrations with 3M 8067 tape—an extremely sticky and tenacious product that earned my confidence.
The vapor barrier is to do double duty as an air barrier. We ran the sheet long over the foundation wall, where it was bedded into a bead of Chem-Link M-1, a low VOC sealant. Later, it will be taped to the exterior wall for a continuous barrier against air, moisture and bugs.
We then laid out and cut the sill plates to length. I chose western red cedar instead of the usual pressure-treated southern yellow pine. The building code requires that any wood in contact with masonry (like a concrete wall) be treated with preservatives or be naturally decay-resistant. Cedar is more expensive, but eliminates any concern about inhaling chemical-laden dust, residue on the skin, or leaching into the soil. Pressure treated wood comes with an environmental cost, and disposal is a problem—-the only option is landfill. The cedar I ordered from the lumber yard (from Idaho), was a joy to work with—dry and straight.
So far, the product I’m most excited about using is Conservation Technology’s EPDM gasket we stapled under the sill plate. It’s a super-robust alternative to the thin “sill sealer” (closed cell foam) used almost universally in residential construction to seal the air gap between an uneven foundation and a wily wood plate. It was fast, easy, and effective. We overlapped the ends about 1” at plate seams for a continuous seal. It compressed to 3/16”, providing a capillary break to any moisture rising up through the foundation wall. We secured the sill plates with Tapcon screws—just a few per board to hold the assembly in place for now.
Finally, we were ready for the excitement of big trucks and the smell of wet concrete. Contractor Josh Spurley of JMS Concrete in Spring Green arrived with his crew to pour the garage slab and the next day, the house slab.
The following day they came back to saw control joints. Curing tarps were secured and with great pride and relief, the first POEMHOME is officially out of the ground!
November 2-3: Crew members Lew & Nino Lama arrived to help me lay foam board on top of the gravel bed. We started with the garage, with one layer of 2” XPS (extruded polystyrene). Of all the common materials used in modern construction, XPS is about the worst for environmental impact. It leaves an ugly trail of pollution from extraction to manufacture to disposal. The only material that could be considered worse is SPF (spray polyurethane foam).
For under-slab insulation, there are few alternatives. I could have bought “Insulfoam type IX” EPS (expanded polystyrene) for about the same price—or Roxul mineral wool for about 4 times the cost. EPS has material properties almost as good as the Owens Corning “Foamular 250” XPS I installed, and acceptable for my application. Most building scientists agree that EPS is more benign than XPS, though side-by-side comparisons are difficult—formulas are proprietary and manufacturing methods vary. Demand from green builders is starting to change the marketplace, and so too is regulation—-Europe is far ahead of us in outlawing HFC’s (hydro fluorocarbons), a “high global warming potential” chemical used to manufacture XPS.
A more tangible environmental impact is how readily cut-offs and scraps can be recycled. While Owens Corning and Insulfoam both claim their product is recyclable, neither company offers a take-back program, and finding a facility within reasonable driving distance has so far eluded me.
My decision to use the XPS finally came down to convenience—it’s stocked by my local lumber yard. I also like that it’s certified by “Green Guard Gold” for low VOC’s (volatile organic compounds—toxic chemicals that pollute indoor air). In my application, the foam won’t be exposed to the interior, but the certification is at least somewhat reassuring. This product also contains a minimum of 20% pre-consumer recycled content.
Insulation under a garage slab isn’t necessary but I think it’s worth the extra cost (in money and environmental impact). If a future homeowner wants to set up shop, the slab will be more comfortable and save on heating. In spring and summer, when warm moist air hits the cooler slab, the insulation will prevent “sweating”—condensation that could cause rust or mold/mildew under and around equipment stored there. We installed one layer of 2” XPS on top of a layer of gravel and taped the joints with 3M 8067 tape—this combination makes a continuous vapor barrier under the slab.
To eliminate any thermal break, we placed one layer (2” XPS) around the slab perimeter and where the future overhead door will meet the slab. To protect this vulnerable edge from damage and UV degradation, I special ordered a galvanized steel channel. The channel installed like a charm and was taped to the foam, with help from friend Marken D’elene. Here’s how that detail looks (NOTE: a future owner will need to insulate the frame wall and build a kneewall from slab to sill plate to complete the thermal envelope):
I knew I wanted a thicker layer of insulation under the house slab—but how much was enough and how much was a waste of money? Code minimum for my foundation configuration is R10, or 2”. To make an informed decision, I used an energy modeling program called REM Design.
I was surprised to learn that creating a “tray” of foam for the slab to sit in was more effective than running sheets of foam down the inside or outside of my stem walls. I also learned that increasing the thickness of the tray edge was far more effective than adding more layers of foam under the slab. The energy model gave me the heat loss for each scenario, and after I figured in material costs, I settled on an R20 edge with R20 under the slab. Here is my detail:
In order to minimize waste—and to avoid having extra sheets lying around the job site getting banged up—I prepared a “sheet foam cut list”. I spent a couple hours in the office with “Sketchup” drawing software, to come up with an optimal arrangement that staggered the upper and lower layers, calculated how many rips of edge foam to make, and showed where scraps could be utilized. I like to think it saved us time on-site and saved on landfill waste.
The first layer of edge foam was placed inside the concrete forms before the walls were poured. This left a 6” wide stem wall—just enough to fasten the sill plate.
It worked really well except where the skid steer continuously drove over the wall, forcing sand between the foam and the concrete. Here’s a picture of that compromised section, which we removed and replaced with a fresh rip of foam:
The mechanical protrusions were challenging to cut around, but a good tight fit was finally accomplished. Gaps in each layer were filled with a Green Guard Gold certified spray foam called “Handi-Foam”.
Each step of the way, I am recording not only how much material we use, but how much waste we generate. According the the University of Wisconsin Extension, construction debris make up 20-25% of Wisconsin landfills. Building an average 1500 square foot home generates 3 tons of waste (let’s assume that’s on-site). A quick internet search finds that a 20 yard, 3 ton dumpster measuring 17’x8’x5′ can be rented for $375. That’s really not a lot of money, so it’s easy to see why it’s more expedient for the average contractor to dump instead of deal with the inevitable waste generated for each task.
POEMHOMES is all about building smaller and smarter, with minimal resource expenditure. A key goal is to take the time to sort and responsibly dispose of waste. The cardboard box the Handi-Foam came in went to recycling. The 4 aerosol cans it dispensed from regrettably went to the landfill. With better planning and more finesse, I could probably cut down to 2 or 3 cans. I’ll continue to try to find a supplier who has more eco-friendly packaging or who offers a “take-back” program. I can also continue to find a better product or a better (still affordable) construction method that eliminates the need for spray foam in the first place.
October 31: After the plumbing was roughed in, a 6” layer of clear stone was laid down. This gravel base is an important stop-gap between potentially saturated soil and the slab I want to stay high and dry. It functions as a capillary break by interrupting the upward movement of water. It also was to become my “radon bed”.
Radon is an invisible, odorless, radioactive gas and the leading cause of lung cancer in non-smokers. According to the Sauk County Health Department, homes in any geographic location can test high—even when their neighbors house tests clean. In my zip code, 68% of homes tested need to install some type of radon mitigation system. Homes built on sandy soils, and homes built on a slab (like mine) are less likely to test high, but the possibility remains. The EPA recommends testing every 5 years, but many experts say testing should be done more frequently—even continuously.
The plumber set a horizontal PVC “tee” fitting into the gravel bed and glued it to a vertical 4” PVC pipe stub. Later, I’ll seal the pipe where it passes through the slab and cap it tightly. Once I move in, I’ll get both a short-term and a long-term radon test kit (readily available online or through the Health Department. Should my home test high, I’ll extend the PVC pipe through the mechanical/storage room and out the north wall terminating just under the roof eave. Any radon gas that seeps up from the ground and into the air pockets between the gravel will be drawn through the pipe and out into the atmosphere where it dilutes to safe levels. Besides radon, any humidity, mold, mildew, methane, pesticide gases, and VOC’s (volatile organic compounds) can make a speedy escape.
This set-up is called a passive system. It relies on the natural air pressure differentials between the interior of a building and the soil below. The “draw” can be accelerated by routing the radon pipe through a warm room, by increasing its height, and by keeping it straight.After extending the radon pipe, I’ll run another test. Should my home continue show elevated levels, I’ll hire a radon mitigation contractor to connect a fan to the pipe terminus. This fan must be located outside the living space in case it malfunctions and leaks gas. In most homes it can be hidden from view in a vented attic. Because my home has a vaulted ceiling and no attic, the fan would have to be mounted on the outside of the house.
In my mind, planning for radon is “best practice” and not an extra cost. It’s consistent with my goals for resource-efficient and healthful construction. It takes the long view by employing a strategy with modest up-front costs as a hedge against later, more expensive interventions.
October 30: Contractors aren’t like office workers. I’ve been asked more than once to meet “at first light”. Dump trucks began arriving before dawn from a sand pit at the base of the bluff, just north of town.
The sand was spread and compacted around the outside of the foundation to bring grade within 8” of the top of the concrete wall. Inside the walls, the sand was compacted more thoroughly in preparation for the next layer: a gravel bed.
A seriously deep trench was dug from curb to south house wall for the water and sewer laterals.
Plumber Gerry Thuli arrived from Dodgeville with coils of copper for the water lateral, lengths of 4” PVC and sundries for the interior plumbing, and a big, black grinder pump—a machine I’m not too happy about having to buy and hope isn’t too noisy when in operation. All the homes in my subdivision are required to grind their waste before sending it through the municipalities pressurized sanitary sewer system.
October 29: My plan calls for a slab-on-stem-wall home, not a framed-floor-on-basement home. It’s an unusual choice for our corner of the Midwest, and a little risky from a re-sale point of view. From a low-carbon-footprint and affordability point of view, it makes perfect sense.
Concrete is a high embodied energy material. That means a lot of energy has to be expended to quarry the materials, transport them, crush & cook them, and deliver the mix to the building site. The less concrete used, the better for the environment.
My stem wall is 4′ high, so compared to a basement with an 8′ ceiling, it uses half the amount of concrete. I considered a few alternatives: Insulated Concrete Forms (ICF) or Durisol block—both of which use less concrete, and a Frost Protected Shallow Foundation (FPSF) which uses even less. These alternatives aren’t exotic, but require some amount of special order and special expertise. One of my goals for POEMHOMES is to make choices that are easily replicated. For my first go at general contracting, I need things to be somewhat “plug & play”. A 4′ stem wall is familiar to the trades—and manageable by me.
Having no basement saves money because there’s no stairway and no framed floor. There’s no need for drain tile, damp proofing, and a sump pump (with backup power). Potential leaks or flooding are eliminated—-and so too worries about mold and mildew. An insulated slab stays high and dry and the hard trowel finish becomes the finish floor. When the sun shines, it soaks up heat energy—releasing it back into the rooms as temperatures cool. A slab can be set on or close to ground level, for easy accessibility. I’ll have one 8” step up—not the usual 20” or more necessary in conventionally framed floors.
Of course there are disadvantages and trade-offs. With a basement, mechanicals are easy to install and switch out. Storage is plentiful, you can build out a rec room or additional bedroom, and you’ve more-or-less got a tornado shelter. A slab commits you to a smaller footprint (sans future addition). You have to find space for a mechanical room and plan ahead for plumbing, electrical, and HVAC runs.
My design has a small walk-in-closet on the main floor for the grinder pump, water softener, and hot water heater. Above is an attic of sorts, for the HRV (heat recovery ventilator) and the ASHP (air source heat pump). Electrical runs and ductwork will be routed across the length of the house above the living areas.
Notice in the illustration above how the slab rests on a 4″ layer of foam (blue), which overlays sand fill (brown). It’s a lot of fill. The lot looks flat, but it’s not.
A tornado shelter—if done to FEMA standards—is a major expense. I’ve wrestled with this, and am satisfied I have a good-enough answer. See future posts for more.
Slabs may not be most people’s preference, but if the Village of Spring Green is going to grow they are inevitable. People here remember the “Flood of ’08”. Rising groundwater—from record-breaking rain the previous summer, record-breaking snowfall that winter, and above-average rain that spring—flooded basements and sent homeowners packing. A whole subdivision—-just a mile north of me—was razed. To forestall more financial ruin, the Village passed an ordinance—affecting lots just a stone’s throw from mine—that restrict basements to storage and utility only—-no “below grade living space”. Other lots require slabs. My goal is to show how liveable, pleasant, and affordable a slab home can be.
October: It’s been a month of slow—but steady—progress at the site, as contractors schedules back up due to heavy rain and end-of-season demand. I keep in touch, trying to entice them to my dry “beach” lot. Up in the surrounding hills, soils are heavy, rocky, clayey, and saturated.
Neighbor Lew Lama of Wood & Stone Works from Spring Green helped me stake the house perimeter and highlight the outline with spray paint. Slaney Excavation dug for footings.
Then, footing forms were set, poured, and stripped by Matteson Concrete from Spring Green. Next, wall forms were set, poured, and stripped A boom truck had to be called in from Reedsburg to reach all the way around my unusual turned-90 degrees-to-the-street design. The wall pour took a mere hour.
The Concrete Remover came from Madison with his special curb-cutting rig. I’d never seen that done and it was pretty cool.
Good friend Mark Morgan from Bear Paw Design & Construction came down from Eau Claire to help me improve the look of the concrete walls where they show above grade. Usually, this area is left as-is—-leaving not-very-attractive ridges every 2 feet where a form panel butted the next. He took on the hard work of power grinding while I knocked off form ties and patched them with a cementitious product that will prevent the embedded steel from rusting out.
Temporary electric was installed by good friend Bob of Rowen Electric from Dodgeville. I helped him wire up the box in the shop and install the post on site. It took real effort to pound down two 6′ long steel grounding rods—once again I was grateful for my sand.
Things get messed up, but also utility flags expire so Diggers Hotline had to be called back before Slaney Excavating could start to move dirt. It will take 3-4 days to lay base for the driveway, fill in foundations, compact for slabs, and complete rough grading.
September 22: The Village of Spring Green is built on an ancient deposition of sand. My lot, at the edge of town, was still farmed in a rotation of alfalfa, oats, and winter wheat. Irrigation rigs and regular infusions of chemical fertilizers made it worth it—-but under my watch, that will change.
I’m concerned about chemical blow-back and dust from farm operations and a little distressed about distant traffic noise. A dense, mixed planting of deciduous and evergreen trees and bushes along the west border will help—and keep cold winds at bay. The rustle of leaves will help mask highway drone. A small earth berm would add sound-deadening mass, and create a sense of enclosure while blocking and filtering soil runoff. Here’s how it could work:
What is home without a large vegetable garden? The topsoil Slaney scraped off was a thin layer, only about 6-8” deep. A scoop shaken with water and left to settle is an easy and accurate-enough way to test its composition. Google “Mason Jar Test”.
Measured, my soil is: 72% sand, 28% silt, with no discernible layer of clay
Ideal garden soil is: 40% sand, 40% silt, 20% clay
Classified, my soil is “Silty Sand” or “Loamy Sand”. It drains quickly (good for foundations), but can’t hold onto moisture or nutrients. For my garden to thrive, I’ll need to add clay and organic matter, with a top dressing of mulch to retain moisture.
Soil erosion is a real problem on most construction sites, and Wisconsin’s Uniform Dwelling Code is pretty strict about what you have to do to control the perimeter. My lots flattish terrain and the sandy soils ability to absorb water quickly means erosion or runoff (sheeting), shouldn’t be a problem—even in a heavy rain event. But protocols must be followed. Options include landscape fabric silt fence (most common), straw wattles (what Slaney recommended), or straw bales—which is what I chose. I agonized, because bales are by far more expensive—and heavy to handle. But I just couldn’t bring myself to buy a bunch of plastic, only to throw the muddy mess away after final grading and established ground covers stabilize the soil. Minimizing landfill waste is a key goal of POEMHOMES.
Straw wattles are better, with only a light weave of plastic containing the sausage-like things. But straw bales come clean (well, there is plastic baling twine). I could get them delivered from a local farmer and can use them later for mulch. With help from my son and his girlfriend, we worked our way around 300 bales—pounding two 2×2 stakes into each one. Spring oats, tossed on the piled up topsoil, should hold it together until next summer.
Later—my attention now keenly attuned to soil erosion—I noticed several very bad silt fence installations. Here’s one that’s been breached. I’m pleased to report that my bales have stayed intact, and there’s no apparent erosion.
August 14: I spent a few hours with shovel and tape measure intent on finding my property corners. The subdivision was platted only 13 years ago, so I was reasonably confident the steel stakes set at that time would still be intact. If successful, I would save myself the $200 a surveyor quoted me to come out and set flags. After overturning more than a few humps of sod, I found all four about 6” below grade. Later, my crew and I will pound wood stakes alongside and run string lines between them to measure off the house perimeter.
September 7: Finally, my building permit is in hand and we are a GO! After many months of drawing, revising, researching, and selecting materials & subcontractors I was ready for plan review. I cracked open my still fresh-smelling vinyl checkbook and cut my first POEMHOME check.
As a professional designer (with an Associate’s degree in drafting), I’ve prepared construction plans for over 120 new homes. Many people are surprised to learn that in Wisconsin—as in many states—residential projects don’t require an architect’s stamp. In fact, anyone can design a new home. Plans have to pass muster, and each stage of construction has to pass inspection—but it’s all within reach of a conscientious person.
A homeowner can pull a permit and build their own house—as long as they subcontract out the mechanical trades to licensed professionals. Anyone who’s building a home for someone else needs to be registered with the State. Even though I’m building this house for myself, I took the “Dwelling Contractor Certification” test and am now a licensed residential contractor in Wisconsin. With any luck, this won’t be the last house I get to build.
September 21: My birthday present this year was a visit from my sister and her smarts to set up this POEMHOMES website. That was back in June, when I was still drawing. She asked me what the latest date was that I could start construction and still beat winter. Overwhelmed, I guessed September 20th.
I was momentarily furious (in a how-dare-you, why-didn’t-you-even-ask-me kind of way), when I later discovered she installed a little calendar app on this website that flipped down to my so-called groundbreaking. I now take it all back, and am thankful for the sisterly nudge. We did indeed begin today, just one day off.
Slaney Landscape & Excavating of Dodgeville texted me this morning that he had clearance to dig. A few days before, he’d called Diggers Hotline to have the site flagged for utilities. He scraped the lot clean of topsoil and placed it in neat mounds on the south edge of the lot. What was left was a wonder to behold—a beach of the finest and softest sand imaginable!
August 1: I feel drawn to particular landscapes and sometimes, man-made places. When that heart-tug comes over me—whether it’s nostalgia, familiarity, or something more mysterious—I know I’m connected to the Earth and I’m alive in the moment. I treasure this feeling.
One such place that draws me is the Spring Green Preserve. So it’s no small thing that from particular vantage points (and by craning my neck), I can see this promontory from my lot. When climbed, this dry sand prairie bluff offers commanding views up and down the Wisconsin River and buzzes with unusual flora and fauna.
Another place is the Wisconsin River, just a mile away—a seemingly endless stretch of sandbars, eagles, herons, and the hush of solitude. Wild edges await at Bakkens Pond—and further west, Smith Slough & Sand Prairie. I often imagine myself back in time, when these paths were lightly trod. Who lived here, how did they make provisions, what did they see and hear?
So you can imagine my delight when I found the original surveyor’s map of the region, platted in 1840 by Wm. A. Burt. He transcribed the contours of the river edge and islands big and small and edged them in blue. My lot sits in the SE ¼ of the NE ¼ of Section 12 at the edge of what was once a 6 mile stretch of a “B. Oak & Pine Grove”. Remnants of this grove can still be seen along the highway just east of Lone Rock.
Note to self: plant a Burr Oak and a White Pine.