June 21, 2018: 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!
April 20 noon-5 pm: We’ve made some good progress on Spring Green’s first net-zero energy home. Take a tour, snap some pictures, ask questions. You’ll see the skeleton structure and what double-stud walls and raised-heel roof trusses look like. Admire the views through the recently-installed windows and ask about their energy-efficiency backstory. Have a look at the still-to-be-trimmed-out galvalume standing seam roof. Find us one block north of the High School at 770 North Westmor Street. Bring the kids, stay for s’mores. For more information call or text Amber at 608-935-9020.
March 29-April 14: My favorite thing so far is the 12 foot wide patio door we installed on a glorious spring day. It’s what’s going to open the living room up to my garden and help heat the house in winter. I chose a Marvin aluminum clad wood slider, with a heavy-duty fiberglass sill. Thank goodness for my crew of Very. Large. Men.
I prepped the sill by securing the under-slab vapor barrier to the edge foam with caulk and measuring out a length of 5” EPDM sill gasket. The patio door sill will sit directly on these materials, completing a continuous thermal-barrier, air-barrier, and vapor-barrier to the exterior.
Mark of Bear Paw Design & Construction and “the boys” hustled the thing into place.
Here’s Mark finessing the gasket, bathed in sunlight. “Passive Solar” was the buzzword of the 70’s that got me excited about architecture and back to school to take a drafting class. Since then, the idea that south-facing windows can serve as heating appliances has been disparaged. Those early, hippie homes with their wall of factory-seconds windows skimped on insulation and leaked like a sieve. They overheated during the day, and without thermal curtains lost all that heat at night. We now know that thick layers of insulation and a double-down on air-sealing are far more important than trying to capture solar energy.
Many high-performance builders shooting for net-zero are building conventional-looking homes without regard for window orientation. Even so, I’m inclined to cling to my roots. My design follows the recommendations of Dan Chiras and his seminal book The Solar House which balances “solar glazing” to “thermal mass”. During the winter when the sun is low in the southern sky, sunlight will stream through my south-facing windows and patio door and its heat energy will be absorbed by my concrete slab. There will be some lag. Some days, it will be cloudy. Other days, the house will get too hot. Thermal mass is slow—it’s slow to absorb heat and it’s slow to release heat.
Here’s where I divide company with the mainstream—I don’t need and I don’t want to live in a thermostat-controlled environment that never, ever varies. I’ll live in a house that responds to our flight across the sky and I’ll save energy by accepting indoor air temperatures that climb to 80 degrees on sunny afternoons and drop to 60 degrees overnight. So it’s slippers for me.
One of the most-asked questions I get is if the slab is heated, meaning with PEX hot-water tubing run through or under the slab. Heated slabs are wonderful. They’re warm to the touch and can carry a well-insulated house through most of the winter with supplemental heat turned on only for the coldest days. But because thermal mass works slow, the PEX system really should be left on continually—leaving very little absorptive capacity for incoming solar. And because it’s slow it can’t respond to a sudden change of weather. Most homes need a backup heating appliance that ideally also supplies air-conditioning. So while wonderful, heated slabs are more expensive than unheated slabs because you’re investing in two—not one—mechanical systems.
To satisfy my curiosity, I ran my design through modeling software REM-Design. Per recommendation, my “solar glazing” is 12% of the area of my “thermal mass”. When I remove the slab, annual heating costs increase by 3.5% and surprisingly—cooling costs rise by 9%. Southern Wisconsin is hot in the summer, but has enough temperature differential between daytime and nighttime (about 20 degrees) to power up the “thermal flywheel” effect. While overhangs will mostly shade my south windows from the direct rays of the sun, August heat will warm the slab during the day. If I keep the windows open and there’s a breeze, that absorbed heat will flush out and by morning, I’ll feel a nice cool underfoot.
Besides the cooling effects of the slab, windows placed for cross-ventilation in each room will keep the air-conditioning off most of the summer. Casements or the patio door can be cracked open a little or a lot to funnel prevailing Southern breezes out North-facing awning windows. High windows enhance the “stack effect”, naturally drawing warm air up and out, all hurried along by the sloped ceiling. The speed of the air can be increased even more when the area of opened window on the windward side is small compared to the area of opened window on the leeward side. Awning windows are perfect for passive ventilation because they can be left open all summer long without any worry about rain.
I chose Marvin Integrity All-Ultrex windows for their rot-proof, maintenance-free finish and long-term durability. They’re less expensive than Marvin’s wood aluminum clad windows but more expensive than common vinyl windows. They’re made from pultruded fiberglass, which takes 39% less energy to manufacture than vinyl. And because they’re 60% glass (silica sand), the frames expand and contract at nearly the same rate as the glazing, making the units less likely to break seal.
Window glazing comes in a dizzying combination of features that effect energy performance, and I gave them all an equal run through REM-Design. Turns out, the most commonly available is also the most cost-effective. I chose “dual-pane, low E2 with argon” which is rated for year-round comfort in Northern and North-Central states. The equivalent R-value is 3.4, the same as one inch of cellulose or fiberglass insulation—not too impressive. There are several (mostly Canadian and European) window manufacturers that make up to R-10 windows, but they are far outside my budget.
Other high-performance builders in our climate zone upgrade to triple-panes and low E1 coatings where south-facing. If I did the same, I could save $59/year in operating costs. However, the package would cost me $2,785 extra or about 28% more. Even when amortized over the expected service life of the windows (30 years), the triple-pane windows never pay for themselves.
The argument then comes down to comfort. It’s true that dual-pane windows are colder and more prone to condensation problems. If you’re sitting next to a cold window in the evening, you’re going to feel a chill as your warm body radiates heat to the cool glass. And you might experience a waterfall-like spill of air and be tempted to turn up the thermostat. Curtains or thermal shades are the answer here, or to paraphrase Frank Lloyd Wright: “move your chair”.
I saved money and resources and kept to budget in another way: my home doesn’t really have many windows. If my design answers the need for natural light, views, and cross ventilation—it works. If the windows are well-proportioned and well-placed to create a harmonious whole with other architectural elements—I have style. But the biggest savings of all: the house is small.
Installing the windows was a satisfying step for me. I chose DuPont’s Tyvek system of flashing products. While it can sometimes seem like you’re wrapping a Christmas present, tape and Tyvek are stronger and long-term more reliable than old-school caulk and tar paper. The products had a quality feel and were easy to use.
I used FlexWrap NF, StraightFlash, and FlexWrap EZ—all butyl rubber flashings that are solvent- and VOC-free. They can be installed in cold weather on cold surfaces, are self-healing, and don’t off-gas. There’s no waste except for the peel-off paper backings. With windows in, the house is warmer and a better place to be.
March 29-31: Spring construction got off to a big start when Mark Morgan of Bearpaw Design & Construction arrived with his sons to install the metal roofing. The pre-cut-to-length roof panels flew on and by Sunday afternoon the work was nearly done—all except for the “gingerbread”. That’s Mark’s term for edge and ridge trims.
We had a good rhythm going with Mark cutting and bending panels at a workbench, Nate carrying and sliding them up to Joel who screwed them down, and me filling in where needed. My work included peeling off the shrink-wrap that protected each panel from the next. I grew more and more dismayed as trash bag after trash bag filled up. Technically, plastic like this is recyclable but the reality is different. Do any of you know a facility?
The panels came drop-shipped in large wooden crates (wrapped in more plastic). The 2x material isn’t good quality and some of it will split when I bang it apart, but I plan to reuse what I can for blocking and bracing. The rest will be firewood. My sales rep recommended I order two extra panels in case of a miss-cut or the wind taking one but we had no mishaps. Mark will take the extras for his shed and I can take scraps to the local recycling place.
The roof is standing seam steel with a galvalume finish that comes with a 25 year warranty. Most estimates put its lifespan at 50+ years, a nice match to the lifespan of the PV (photovoltaic) panels that will cover a third of the house roof. An installer I spoke with told me that to take down and put PV panels back up for a re-roofing job he’d need $2000—-a cost best avoided.
Metal roofs aren’t very common for homes in our area. They’re more expensive, so to recoup your costs you need to be in the house a LONG time or be confident there’s resale value. Many people find them too stark, too commercial-looking, or too modern-looking and in some cases I agree.
I chose galvalume instead of a painted finish because I like the way it looks and it goes with the casual, contemporary style of my house. You can get steel in lots of colors but unless it’s gray I think it looks cheesy (think Pizza Hut). The galvalume fits my aesthetic because it will take on a weathered patina much like a well-used cutting board. The more common choice—asphalt shingles—wouldn’t meet the long-term durability and low-maintenence goals I set for this project. They last only 15-20 years and while in theory can be recycled, usually end up as landfill. Steel is recyclable at the end of it’s useful life. But to honestly evaluate the “green credentials” of various roofing options you’d have to compare their embodied energy—a moving target that only a few scientist-types have attempted. It includes the energy to extract, to transport, to manufacture, to install and maintain, and finally to dispose of.
With the roof on, I can now turn my attention to windows and doors!
Noon to 4 pm: You’re welcome to stop by and see my house under construction in Spring Green, Wisconsin. The walls are up and the roof is on so you’ll see what double-stud framing looks like and how the raised-heel roof trusses create space for an extra-deep layer of insulation. If you’re curious about what a smallish (1200 square foot) home feels like or want to learn more about super-insulated, passive solar, net-zero energy design I’m there to answer your questions. We’ll have a little campfire and refreshments too!
March 2, 2019: My house is a throwback to 1955. That’s the last time the average new home built in America was 1200 square feet. By 2014, the average new home ballooned to 2657 square feet—even while families got smaller. Today 62 out of 100 households are just one or two people.
I meet people all the time who want to down-size. As an empty-nester myself, I can relate. A big house is too much work. It takes a lot to heat and cool. Steps can become a problem. Older homes need updates and don’t adapt well to modern lifestyles but newer homes are big and boxy and lack character. Living in the country is nice but can be isolating and you’re forever driving back and forth to town.
As a designer who’s listened to hundreds of families describe the good and the bad of their living situations, and as a builder who wants to make a difference, I see an under-served market.
At first, I didn’t think I would be able to build the house I wanted on the lot I wanted. Like most subdivisions, mine has Covenants—certain minimum requirements laid down by the developer to insure a sort-of uniformity to the neighborhood. The minimum size for a one-story home was 1500 square feet.
Turns out, rules are negotiable. My Offer to Purchase was contingent on approval to build a 1200 square foot home. As soon as it was accepted, I hit the drafting board.
Whittling down a wish-list takes some time, a little work with a tape measure, and a bit of inspiration. Of course, not everyone will make the same calculation I did, but here’s what made the cut and what didn’t:
NO HALLWAYS: Eliminating hallways is hard to do in a large home but pretty easy to do in a small home. Each bedroom is on either side of the great room, not lined up along a bedroom wing. The kitchen is a galley with standing space doing double duty as the main circulation route. The laundry is a smallish “room” that you walk through to get to the bathroom and bedroom.
NO CLOSETS: Instead, there are built-in cabinets for coats, clothes, pantry, and cleaning supplies. This saves space usually taken up by 2×4 wall framing.
NO STAIRWAY: There is no basement and no second floor. Instead, there’s a narrow ladder-stair to attic-like space for bulk storage.
NO DINING ROOM: A nook off the Living Room is convertible to informal dining, homework, crafts, games, or TV area.
NO FOYER: Instead of two rooms—one for guests and the other a mudroom, there’s a single way in with a place to hang coats and drop boots that does double duty as the main circulation route.
NO LAVISH MASTER BATH: Each of two bathrooms is a modest size with a tiled walk-in shower. There’s no tub.
YES WINDOWS: The number of windows is modest, but their size varies from small view-port to over-scaled, adding drama and bringing attention to particular views. Each room has windows on two sides to balance light and draw in fresh air. Each bathroom has a window.
YES VAULTED CEILINGS: I splurged on volume but keep things cozy by layering in wood beamed ceilings over the kitchen, entry, and bathrooms. The rooms feel bigger and airier and more spatially complex. Diagonal views both up and out extend views and expand space.
YES OUTDOOR LIVING SPACE: There’s a breezeway-style porch for summertime dining and lounging and a walled garden/patio for campfires and watching the stars, both just steps away from the kitchen. I’ll live mostly outside 6 months of the year!
December 10-21, 2018: Watching the crane swing the roof trusses in place was a thrill, and once all were set into place the house began to take on a shape you could feel.
Manufactured roof trusses are an economical choice and at 24” deep can clear-span the width of my house. The deep cavity provides a built-in space to fill with insulation (more on this in a later blog post).
The style of my house calls for deep overhangs and generous rakes. Like the brim of a hat, the eaves will deflect rain away from the walls and provide the shade I need to help keep the house cool in summer. I used Sketchup, a 3D modeling software to visualize my design. I played around with thickness and depth of eave to get the look I wanted, and dialed in day of month and time of day to find out where shade lands on the Summer Solstice, when the sun is highest in the sky. I found out I needed a 30” overhang to get full shade on my south-facing windows. On the Winter Solstice, when the sun is lowest in the sky, the windows are in full sun, capturing free heat energy.
The problem is that mid-June isn’t the hottest month, and December isn’t the coldest month. To optimize shade, I should look at July which weather data says has the most “cooling degree days”. To optimize passive solar heat gain, I should make sure my windows are in full sun in February, the month with the most “heating degree days”. I found that cutting the overhang back by 8” gave me full sun on February 15th , but exposed the windows to way too much sun on July 15th. (Note to fellow building science geeks: also play around with truss heel height, wall height, and window placement).
To build a strong, wind-resistant overhang, I upgraded the truss “tail” (top chord) from the usual 2×4 to a 2×6. For each rake, I specified two dropped top chords supporting 2×4 flat “lookouts”. These cantilevers were then reinforced with 2×4’s on edge.
Instead of the usual 2×6 “sub-fascia” covered with a 1×6 “finish fascia”, I kept things simple and straightforward with a 2×8 cedar fascia screwed directly into the truss ends. Cedar is naturally decay-resistant and needs no paint or stain. In this way, I haven’t “sandwiched” materials that might get wet and stay wet, hiding rot from view.My overhang is what’s called a “boxed-in eave”. You see it on farmhouses around here that retain their vintage forms, although their roof edge would have a “square cut” not a “plumb cut” like mine. I’ll need the plumb cut to attach the large gutters I have planned.
Newer homes or remodeled older homes usually have “soffited eaves” that while practical, can look awkward. High-end newer homes or Arts & Crafts homes sport “exposed eaves” which I love but are considerably more complicated and expensive to build.
Each roof truss was secured to the wall framing with a Simpson truss screw instead of the usual hurricane anchor. It’s simpler and faster and can be installed from the inside. I upgraded the nailing protocol for the roof sheathing to match the wind-resistant specifications I used for the wall sheathing. For underlayment, the crew rolled out a double layer of Titanium UDL 25—a synthetic air, water, and vapor barrier—and attached it with cap nails. It’s rated to perform up to 240 degrees, a requirement where PV (photo-voltaic) panels are installed.
It’s become common practice to roll “ice & water” peel-and-stick membrane at the lower edge of a roof as a hedge against ice dams. I’ll save the expense because my roof will have:
1. uniform heat loss across the entire roof area (insulation doesn’t thin @wall)
2. minimal heat loss with 20 inches of dense-pack cellulose
3. minimal heat loss because of air-sealed ceiling cavity
4. vent chute above insulation keeps underside of plywood sheathing cooler
5. metal roof promotes snow shedding
December 21st was a pretty sweet day because the crew got the underlayment down even as night was falling and we enjoyed a beautiful sunset. It was our last day before the holidays and as it turned out, our last day. Winter arrived and hasn’t let up. We’ll be back in March……for sure by April!
December 10-21, 2019: While my crew was busy framing the eaves and laying down roof sheathing, I tackled the exterior air-sealing.
Stopping air from whistling through random cracks is an essential step to meet my net-zero goals. Taking the time to caulk and tape each and every joint adds up to energy savings. It also makes a home more comfortable by eliminating drafts, cold spots, and uneven indoor temperatures. I can be confident that my house will last for the long haul because moisture-laden and dust-laden air can’t enter the wall and roof cavities. My insulation and framing will stay dry, which means mold, mildew, and wood decay can’t take hold. And a not-to-be-taken-lightly side benefit: carpenter ants, cluster flies, Asian beetles, and mice are stopped cold.
With all these benefits, you’d think exterior air-sealing would be standard practice in residential construction—but you’d be wrong. Sheathing seams are left untaped. Builders assure themselves that a layer of housewrap is enough to ward off wind and rain. But from what I’ve observed, it’s often hastily tacked up. Seams are sloppy and mechanical penetrations are haphazardly sealed. Siding covers all sins and buyer beware!
Several visitors to my building site have been surprised to see my use of plywood sheathing—not the more common OSB (oriented strand board). Plywood is a reliable air-barrier and can tolerate some saturation. OSB has been found to leak air when pressurized during blower-door testing (more about this in a later post), and is more vulnerable to decay when repeatedly wetted. A good alternative to stock OSB is Huber’s ZIP sheathing which has a factory applied coating that replaces housewrap.
Plywood scores worse for efficient use of wood resources (it requires larger diameter trees and generates more waste), but it uses less glue than OSB. It’s also more expensive: I chose 5/8” 5-ply fir, a significant upgrade from code-minimum 1/2” OSB. My decision to use plywood came down to its durability, and the advice of many building scientists who say it’s the “least risky” choice for thick double stud walls like mine. When packed with 12” of insulation, the plywood sheathing will stay cold—much colder than in a thin wall that rapidly loses heat to the exterior. The plywood can become a “condensing surface” (like window glass) if the drywall is breached and moist indoor air finds a convective pathway.
My first step was to caulk seams wider than 1/4” and tape narrower seams. I chose the same caulk (ChemLink M-1) I used for the under-slab vapor barrier where it seals to the top of the foundation wall. It’s a waterproof, non-shrinking, low VOC sealant that can withstand joint movement in excess of 35%. It was very easy to work with and had no apparent odor. The tape is 3M’s All Weather Flashing Tape 8067, selected for its good track record.
Caulk and tape are more reliable than foam products because they remain flexible. They hold up to thermal expansion, structural settling, lumber shrinkage, and wind stresses. Foam is brittle. It can pull away, leaving hairline cracks that link outdoor air to indoor air.
At the bottom of the wall, I folded up and taped the under-slab vapor barrier that I had let run long (see blog post “Sills & Slabs”). Now married to the plywood sheathing, it completes the continuous air barrier at this critical juncture.
At the gap between the truss tails and the wall sheathing, I used DuPont’s FlexWrap EZ, a flashing tape that takes a curve. Later, I’ll use it for mechanical penetrations. On the inside, a “vent chute” will complete the air-barrier at the top of the wall (more on this in a later post).
My next step was to roll out the housewrap. A few green builders swear by old-style tar paper (asphalt impregnated felt), but most agree that synthetic products tear less and hold up better under repeated wetting. They are also lighter and easier to install. Known to the trade as “Weather Resistive Barriers”, a good quality housewrap is wind-resistant, waterproof, and vapor open.
I chose DuPont’s Drainwrap which has a slightly crinkled surface to facilitate water drainage behind the siding. With help from friend Bob Rowen, we got a nice tight fit around corners and secured it with caps. Simple stapling wouldn’t hold up in my windy location. We kept clear of window and door openings.
The caulk/tape/housewrap method takes patience and many steps. There are other ways to air seal including sheet foam, spray foam, fluid-applied membranes and peel-and-stick sheets—all more expensive in material but may come with a savings in labor. What I’ve chosen is simple, readily available, and easy to execute or adapt when future changes are made.
When spring comes around we’ll install a combination of vertical wood and horizontal cement board siding. Siding is the first line of defense against rain, wind, and snow. Any water that sneaks past will hit the housewrap and drain down. If the housewrap is breached, the plywood can take the blow. Each layer deflects water and wind, and does so while staying vapor-permeable. Any moisture that’s absorbed can eventually evaporate. The wall can dry to the exterior when the sun comes out and warms surfaces. Or it can dry to the interior when the indoor air is warmer and drier than the outdoor air (more on this in a later post).
I hope what I’ve described here makes sense to you whether you’re a fellow builder or a homeowner. Please let me know if you have any questions or insights of your own on the fascinating topic of air-sealing!
December 16, 2018: 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, 2018: 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, 2018: 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, 2018: 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, 2018: 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, 2018: 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, 2018: 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. 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, 2018: 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, 2018: 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, 2018: 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, 2018: 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.
June 20, 2018: After 30 years living in the country, I began to think about moving to town. Like many people nearing retirement, I was looking for a way to simplify my life and reduce the daily chores and maintenance demands of owning a large house and grounds. Putting down new roots in a friendly place where I could walk to the library and meet people at the coffee shop sounded good. For me, that friendly place is Spring Green, Wisconsin.
My heart was set on a contemporary, net-zero house—a house that didn’t yet exist. Finding a suitable lot took several years and an evolution in thinking. I envisioned my smallish, modest home tucked along a tree-lined street, in an older neighborhood close to the activity downtown. It would be similar in size to nearby houses, with their quirky arrangement of old garages and tool-sheds that created private little backyards and cozy gardens. Out front—a sidewalk, with people passing by.
One lot slipped through my fingers because I wavered. Another lot befell a similar, more complicated fate. I kept biking around and around the neighborhoods, looking for some “lost” parcel. The only listings were on the fringes, out in the bleak and bland subdivisions. Or so they looked to me.
One day I stopped and had a good look around. Big, boxy homes, check. Vinyl siding and faux stone, check. Overly large lots with no trees, check. Wide streets and large front-facing garages, check. No sidewalks, check.
But then there was one. Maybe I could make it work. It was a 20 minute walk from the coffee shop. Nearby woods and an open field beyond made it feel like country. No trees on the lot meant more solar heat gain and sunshine for a vegetable garden. I could plant a windbreak along the west edge. If I turned the house 90 degrees, I gained some privacy while still putting on a neighborly face.
Like many subdivisions, there were covenants. There were two that rubbed the wrong way. The developer required that any plan include an attached two-car garage and that any one-story house be at least 1500 square feet. My plan was only 1000 square feet, with a semi-attached one-car garage.
I noticed that around the corner was row of smaller-looking houses on smaller-looking lots. I found out the size restriction for those lots was just 1200 square feet. So in my offer to purchase, I included a drawing showing a 1200 square foot house with a semi-attached two car-garage, facing away from the street. My Realtor later said she’d expected some pushback.
Here’s a preliminary plan of how I’ll arrange the house on the lot, and how I’ll use landscape to enhance energy-efficiency. A mixed, densely planted windbreak (ideally planted on a low berm), protects the house from winter winds and driving rains bearing down from the northwest. A retaining wall surrounds the vegetable garden and raises it up to the level of the house for easy access. The rest of the yard follows natural grade, directing storm-water runoff to a rain garden where it can slowly recharge the aquifer. Out front, prairie grasses make way for no-mow or low-mow grass in a nod to suburbia. Deciduous shade trees placed along the east and west provide cooling breezes without blocking sunshine to the large windows facing south and the PV array on the south roof. If possible, I’ll lay pavers or pour a permeable driveway instead of the concrete driveway required under the covenants. Permeable concrete is made from gravel and cement only—the sand component of conventional concrete is eliminated—so that rainwater flows into the surface instead of sheeting off the surface. In this way, the aquifer is recharged and pollutants from car oil, etc have a chance to decompose instead of polluting surface water.
While my smallish, contemporary house might look like a duck out of water next to it’s more conventional neighbors, my hope is that it also looks like it makes sense. My plan is to break ground in September 2018, or if that’s rushing it, then May 2019. I hope you’ll continue to follow my progress!