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!
Saturday October 19 from 10 am to 5 pm: Please join me at the building site to talk about how we can transform our homes from energy-wasters to energy-producers. See how our first model home plans to solve the problem of cold, drafty rooms and high monthly fuel bills, and if it’s a sunny day watch the electrical meter “spin backwards”.
And check out our latest project: “in-ground gutters”. Instead of conventional gutters and downspouts, I had my excavation crew lay down a 12″ deep layer of washed river stone in a trench under the eaves. The trench prevents erosion at grade and splash-back on the siding. Rainwater flows freely through the gaps in the stone and seeps through the sand bed below. If I had a basement and/or heavy clay soils, plastic draintile run downslope to a drywell or daylight would be in order. This strategy would serve the same function as downspouts with extenders—getting the water away, fast. My site is easy: no clay, no rocks, no standing water, no muddy boots. The Village is built on the ancient bed of the Wisconsin River. Life is a beach!
Saturday September 28 from 10 am to 6 pm: Can you stop by (maybe after Farmers Market and brunch at the General Store) and see what we’ve been up to at Spring Green’s first net-zero energy house?
The loft is taking shape and now instead of pointing up and waving my arms in the air and struggling to find the words to explain my design, you’ll see for yourself how it might work. We’re building it with rough sawn lumber that came from a towering White Pine at the corner of Winstead Street & Monroe. Do you remember it?
My friend Jim Birkemeier of Timbergreen Farm felled it, hauled it home just north of town, milled it into planks, stacked it in the solar kiln, let it dry, ripped it into boards, ran it through the saw to make tongue & groove flooring, and stacked it neatly for me to pick up.
This is about as local and low-carbon footprint as you can get! Have you hugged a tree today?
June 1-September 13: Working with wood “for show” is rewarding and I spent many pleasant days sealing 1×4 pine boards for the soffit and 1×8 pine boards for siding. By the time my crew showed up, I had an impressive stack.
We started on the underside of the roof overhang, and hit on what might be an original idea—spacing the 1×4’s apart the width of a nail to create an integral vented soffit. The corners turn like a woven basket.
Most modern homes or remodeled homes have unremarkable “punched tin” soffit panels or metal strips. So unremarkable that I bet most people (not counting architectural snobs like me) take no notice. Look at a historic home and you’ll see boards—often with a interesting pattern or molding added.
Code requires roof venting where fluffy, air-permeable insulation like fiberglass or cellulose is used. Impermeable sheet foam or spray foam doesn’t need venting. The idea is that if warm moist air from the living space penetrates the attic or roof cavity, it can escape. The slots in my soffit will supply more than enough air flow through the 3” deep vent chute we built back in April (see blog post “Vent Chute”).
I shopped around for siding. Cedar is naturally decay-resistant but pricey. Rough-sawn wood in any species looks great and holds a finish better but also costs more. I looked at locally milled wood and visited several Amish farms. I trolled Craigslist and called up area lumber yards. The best deal I found was from Cedar Direct, just a few miles down the road. They import white pine from forests in British Columbia that are certified SFI (Sustainable Forestry Initiative) or from Central Oregon forests that are “selectively harvested”—not clear-cut. The price was right and the quality was good. Delivery was DIY.
I sealed the the boards with PolyWhey, a water-based sealer derived from whey—a byproduct of cheese making—from Vermont Natural Coatings. Whey is a natural bonding agent that displaces the toxic ingredients found in more common polyurethane. The manufacturer claims their product contains up to 45% renewable ingredients and is made in a plant using 50% renewable energy. When applied, it creates a non-toxic waterproof barrier, and protects again UV degradation, mold, and mildew. I found it easy to brush on, easy to clean up, and had virtually no odor. The matte finish lets the grain and coloration of the pine show through without a plastic-y look.
PolyWhey is ultra low VOC (volatile organic compounds) and meets “CA Prop 65”—the toughest environmental standard now in force in California. The standard disallows any product that contains any of the 900 chemicals that have been linked to cancer, birth defects, or other reproductive harm. PolyWhey also complies as Red List Free—a worst-in-class list of materials found in the building industry.
I ordered the sealer in 5 gallon plastic buckets instead of 1 gallon plastic containers. It wasn’t less expensive this way but I knew I could always use another bucket. Plastic containers are, in theory, recyclable—though as many of us are learning, it’s not so easy to find a facility that takes them or may take them but landfill them.
Leftover product isn’t classified as hazardous waste, and can be dried and discarded—but it’s not clear where. Because I sealed the boards before the crew chop-sawed them to fit, I have quite a few cut-offs. I contacted the manufacturer about burning or landfill. The rep admitted there isn’t any official recommendation, but said he personally would without hesitation burn them in a camp fire. So thats what I’m going to do.
I hope the fresh appearance of my pine lasts a long time, but of course no one is going to hand me a guarantee. The USDA publication “Build Green: Wood Can Last for Centuries” points out that when wood is installed properly, it doesn’t deteriorate. Decay can be prevented. The culprit is fungi who attack the cell walls of wood in the presence of moisture, air, and favorable temperatures. On siding, we can’t control air or temperature, but we can control moisture.
My wood siding counts as a sustainable choice if I can keep it dry and on the house for a long time. I can’t control the needs or whims of a future owner, but here’s what I can do as the original builder:
But why go through all the work and worry when I could chose vinyl, steel, aluminum, wood composites, stucco, or brick? All have positive attributes, and promise low-maintenance. Vinyl is the least expensive and most common siding here in the Midwest, and many in the green building community argue its environmental impact isn’t so bad, even though it depletes fossil fuel reserves and uses a slew of chemical additives. It sheds water well, is inherently “back-vented” to allow the wall behind to drain and dry, can last 40 years, can contain some recycled content, and can be recycled (though most tear-offs still land in a dumpster). Here’s a good article: Pro/Con: Vinyl is Green. And here’s another take on it: The Seven Deadly Sins of Vinyl.
Wood is abundant, renewable, low-tech, and requires far less energy to make than metal or cement-based siding products. It can be a source of local jobs and spur on a more regionally-based economy (more on this in a future blog post). Its disposal doesn’t place a burden on future generations. What will our post-post-post industrial society look like in 2060 when today’s vinyl siding or steel is slated for recycling?
Each homeowner has their own preferences, place value on certain architectural features but not others, and bet on different products. Each building material we use has environmental costs associated with their material extraction, manufacture, transport, and disposal—but there is no difinitive source that tells us its durability or carbon footprint “score”. There are just too many variables.
Green building usually means reducing operating costs by adding layers of insulation and products like high-performance windows. But today, more attention is being paid to the carbon footprint of the products themselves—especially as climate scientists warn of an ever narrowing window of opportunity to reduce our carbon emissions. Does it still make sense to build an uber energy-efficient home if the materials used cause more climate disruption today than the cost to heat and cool the home over these next, crucial years?
Alas, the best choice is to not build at all. Refuse, Reduce, Reuse, Recycle. More on this in a future blog post.
June 26-July 12: My crew was impressed with how sturdy and how easy it was to work with the cement board siding I ordered through my local lumber yard. My design called for lap siding on the garage and as a “skirt” to wrap the base of the house. I chose James Hardie’s extra-thick “Artisan” series in a 7 inch reveal with smooth texture for its strong character and robust shadow lines.
The crew did a great job planning the joints to reduce visual distraction and material waste. Installer-friendly features include an integral tongue & groove for a tight butt joint and excellent rain-shedding ability. The boards are nailed “blind” and “off stud” to avoid tear-out at vulnerable edges. Alignment is a sure thing with a galvanized steel “joiner” from Simplicity Tools placed under each joint. Corners are finished with another steel accessory, for a look reminiscent of a mid-century rancher. However, the installation left a worrisome gap at the bottom, a place bees might like to nest. I made the hole inhospitable by packing it with inexpensive stainless steel “scrubbies”. A rough-sawn cedar sill caps off the skirt.
Fiber cement sidings “green” credentials are debatable. It’s mostly cement, with cellulose fiber added as a binder. Mixed in, but not disclosed on the packaging or the Safety Data Sheet, are James Hardie’s proprietary ingredients. Cement is simply crushed rock—abundant and benign. But processing it and forming it into something you can nail onto your house burns up a lot of fossil fuels. It’s estimated that cement plants account for 5% of the global emissions of carbon dioxide, the main cause of global warming.
To their credit, James Hardie claims that 75% of the products raw materials are locally sourced, including the portland cement, cellulose pulp, sand, and water. These raw materials are low in toxicity, and the siding poses no health concerns in ordinary handling. However when cut, drilled, or crushed the dust is an inhalation hazard. My crew used a proprietary James Hardie saw blade designed to minimize dust and set up outside, away from people and buildings.
Like most manufacturers, James Hardie is cagey about disposal. Their Saftey Data Sheet says to dispose of in a “secure landfill, or in a way that won’t expose others to dust”. I talked with a representative, and in the end decided to toss my cut-offs on site. They’ll be fill for the driveway, displacing the amount of gravel to be hauled in.Using a high embodied-energy material can be justified if you don’t use much of it and you design for a long service life. I can’t predict what a future owner might do, but here’s what I can do:
I love to paint. Sure it can be messy and a pain, but in the category of work I find it enjoyable. Most James Hardie products come with a factory finish, but in the thickness and width I chose it only came primed. That gave me the chance to pick my own hue and to try out a best-in-class eco-friendly paint.
I chose ECOS Paints in a matte gray, and it went on smoothly. Coverage was good, though there was some objectionable odor. Clean up was a breeze. Life expectancy is 15-20 years.
The paint can be purchased directly from the manufacturer, or through a distributor like Green Building Supply. The reviews at GBS were compelling. The paint is non-toxic and has zero VOC’s (volatile organic compounds). ECOS was the first and remains the only paint manufacturer to meet the strict labeling of both “DECLARE” and “Red List Free”.
DECLARE is a disclosure statement with more transparency than the more common Material Safety Data Sheet (MSDS)—it requires listing ALL ingredients, right on the label. Red List Free means the product doesn’t contain ANY of the thousands of known hazardous chemicals. Leftover paint and the empty containers aren’t classified as hazardous waste, so can be left to dry then tossed in an approved landfill.
The house is taking on a handsome look, and I hope you’ll stop by and see for yourself. You’re welcome anytime!
Saturday August 10 from 10 am to 6 pm: Stop by and see what we’ve accomplished in the last couple of weeks. The slotted wood soffit is in, looking smart and doing its job to keep the insulation and roof framing dry. Horizontal cement board siding skirts the house and wraps the garage, now sealed with “Red-list Free”, low VOC, made-in-America paint. Inside, rooms are framed out and waiting for mechanicals. Learn how double-stud walls and other energy-efficient details will make this Spring Green’s first net-zero energy home!
Saturday July 6 from 10 am to 6 pm: The house is taking on a handsome look as wood siding and soffit go up piece by piece. When we fire up the saw, we’re running on clean energy—the solar panels are now hooked up to the grid. Inside, you’ll still see the skeletal structure of the double stud walls and the barn-like open space. Wait till next month, and each room will be defined by their stud walls. I’m just back from the Midwest Renewable Energy Fair where I gave a talk on our progress and plans for a new vision of suburbia. Come see what we’re doing, ask me questions, and tell me what you’re looking for in a modern home!
Friday-Sunday June 21-23: Have you been wondering what you can do to reduce your carbon footprint? Would you like to help build a straw-bale wall? Get a good look at the latest electric cars? Learn how to raise chickens? Can you picture yourself eating pizza from a outdoor wood-fired oven? Listening to live music while lounging in the grass? If so, you can’t go wrong at one of my all-time favorite events: the Energy Fair in Custer, Wisconsin.
I’ll be giving a talk about building Spring Green’s first Net-Zero Energy house on Sunday at 10 am called “Follow the Build-Part 1”. Here’s the link to my presentation:
I hope to see you there (or at the beer tent).
June 3-5: At last I was ready for insulation. For good reason, the type of insulation, where to install it, and how to install it is of obsessive interest to green builders like me. Other building materials might be the same, but insulation is where we veer off. I chose dense-pack cellulose because there’s no other insulation that takes less energy to produce, uses more recycled content, and is less toxic to people and animals. Not counting direct-from-the-earth materials like straw bale, straw-clay, cordwood, log, and cob.
Yes, I did consider straw. But for my subdivision house geared to taking super-insulation and net-zero mainstream, I’ve heeled close to convention. All I’ve done is make deeper cavities and prioritized initial cost over operating cost.
There aren’t many contractors set up for this kind of work. Wallace Kennedy and sons of Accurate-Airtight Exteriors arrived from Madison to install what turned out to be the most number of bags ever for a dense-pack job. Wallace packed 238 bags in my 22 inch deep truss cavity, for a total R-80. That’s double code minimum.
The insulation comes from Champion Insulation in nearby Fond du Lac. It’s made from wood fiber paper stock and claims 85% recycled content. By weight, it’s 84% cellulose, 14% boric acid, and 2% starch—all benign materials that pose no threat to the environment. It doesn’t cause skin irritation like fiberglass, and has little or no smell—though breathing the dust should be avoided.
Cellulose reduces sound transmission, and when dense-packed resists air movement, fire, pests, and vapor diffusion. Because it’s hygroscopic, it can take on and release moisture from surrounding materials like sheathing. This protective characteristic makes it especially favorable in double-stud walls. The added borate aids in resisting mold and insects.
Cellulose is a “low embodied-energy” material. That’s the energy it takes to source its ingredients, manufacture and transport the product, and dispose of the product at the end of its useful life. Side-by-side comparisons with other insulation types are hard to come by. Cotton, wool, and cork are more energy-intensive and cause some pollution, while fiberglass, mineral wool, and all the foam insulations pose significant risks.
It took the crew 3 (monotonous) days to complete the job. Wallace stayed on hose, while the younger men fed the blower machine. By the end, the vapor retarder at each truss bay was sealed up—ready for the 12” strip of drywall that will complete the airtight lid of the house. I’m grateful for their conscientious work!
May 24-29: Time was running out. I wanted to have things looking nice for my June 2nd Open House, but I could tell after just a few hours of scrubbing that getting the slab ready to seal was going to be a long and grueling ordeal.
During the planning process, I made the decision to go with a “raw” concrete look: no stains, no stamping, no pattern cuts. No grinding or polishing to reveal the aggregate. No faux finish and no visual tricks. Above all: honesty of material. A simple matte finish would save money that could be put towards fabulous area rugs. Plain with a touch of luxury would suit my style.
I’m not one to rush out and buy expensive equipment or take a chance on a rental that may or may not get the job done. I also don’t like to hire out if it looks like something I can do. All it is, is work. Stubborn stick-to-itiveness and shear parsimoniousness has made for many a long day.
The slab was well-cured after 6 months and it was finally up to temperature. Over the last several weeks, I watched as my borrowed infrared thermometer read out 40, then 50, then 60 degrees. I had my plumber install a hose bib and the Village hook up a meter. I broke down and bought a shop vac and a stiff push broom. I watched a couple of YouTube videos about how to apply muriatic acid (it micro-etches concrete and prepares it to “grab onto” a sealer), and invested in a spray bottle, rubber gloves and a mask. I was good to go.
By sections, I scrubbed the slab 3 or 4 times (just water, no soap). When the water finally vacuumed up mostly clear, I applied the prescribed dilution of muriatic acid and watched it bubble & mist. I rinsed 2 or 3 times then let it dry for a few days before brushing on a test patch of sealer where the cabinets will go.
I chose ECOS Paint’s “Concrete Sealer”, a zero VOC, no odor, water based acrylic product that was easy to use. It carries the “Red List Free” label from Living Future Institute for not containing any of the worst-in-class materials prevalent in the building industry. I hoped to save time by rolling it on with an 18” wide paint roller but quickly saw it left tiny bubbles. I switched to brushing it out on hands and knees.
Two coats got me an interesting finish that I kind of liked but told a friend that “10 out of 10 people will find this unacceptable”. My prediction was way off: at my Open House, many people commented on it and likened it to a natural stone floor. The finish seals out water (I tested it), but took to the concrete in a mottled way. Some areas are shiny, others are dull. The look is growing on me! What do YOU think?
May 20: Sometimes, conventional wisdom should be questioned. In this case, it’s the conventional sequence of residential construction. Today, the drywall crew arrived to “hang the lid”—builder speak for installing ceiling drywall.
In my quest for a super air-tight house, I decided to eliminate all electrical and mechanical penetrations through the ceiling and to insulate it and drywall it before framing out interior partition walls. While it takes separate set-ups for each crew and some flexibility in scheduling the next phase, it does make the actual job easier and faster.
Drywall is relatively cheap and it’s common to add a few sheets in case of a miss-cut, but I wanted to reduce waste. I also wanted to try out a product called Insta-Back that eliminates the need to cut drywall back to the nearest truss. I came up with a plan that saved 4 sheets of drywall, reduced the number of seams to be taped, sped up installation, and left me with a manageable pile of scraps at the end.
My plan called for cut sheets at the perimeter only and full size sheets in the field, run past their truss supports. All lengthwise seams are factory. Butt seams are joined by Prest-on’s “Insta-Back” drywall clips that promised a “bump-free” joint with a 1-2 degree taper, similar to a factory joint.
Adam Esch of Esch Drywall appreciated the wide open space to roll his scaffold and did a great job. But I could tell he wasn’t too impressed with the clips. Later, I went back through with a level and determined that of 20 butt seams, only 2 had the requisite taper, while most simply held their own by laying flat. I’ll have 3 or 4 bad joints to deal with. At this point, I’m not sure if the problem can be blamed on the Insta-Backs, or the adjacent trusses. For the walls, I may try another product.
I chose 5/8” thick USG’s “EcoSmart” panels for their long list of green credentials and green certifications. The upcharge was under $20. The panels are significantly lighter and use less water in the manufacturing process. The ingredients are so benign, I tossed scraps at the edge of my lot to decay into the soil.
We left a 12” gap down the center of the ceiling at the request of the insulator. He’ll use the gap to snake his hose into the truss cavities. Later, we’ll fill the gap with 1/2” thick drywall for a smooth connection to the factory seams. Here’s hoping drywall mudding and taping will go well, because I’ll be tackling it by myself!
May 18-19: The latest buzzwords are “smart & sustainable” and I’m saying them but thinking ruefully of all the things builders and industry get wrong and have to walk back in say, a couple of decades. It was on my mind while on a ladder while wrestling with a 50 foot long roll of so-called “smart” vapor retarder.
Today’s homes are much more vulnerable to mold and decay than older homes because they’re slow to dry out if they get wet. We pack wall and ceiling cavities with insulation, and cover surfaces with materials that trap or retain moisture. When driving rain sneaks past cracks & crevices and soaks in, a day or two of sunshine isn’t enough to make things right.
Inside, a family of four can create 2-3 gallons of water vapor a day when cooking, bathing, and washing—and all that moisture can find an exit through a hundred sloppy construction holes.
An older home is like a wood box. A new home is like a wood box lined with sponges imperfectly wrapped in plastic.
Since the 1970’s, building codes in cold climates have required a vapor retarder installed on the “warm side” of a wall or ceiling. It can be old-school kraft paper that comes with fiberglass batts, but is usually 6 mil polyethylene stapled to the face of the studs and covered with drywall. Poly is a Class I Vapor Barrier, practically impervious to water vapor. Kraft paper, once maligned as too loosy-goosy, is now considered “smart”. It’s a Class II Vapor Retarder, which means it can stop some but not all vapor.
The problem is that with the advent of air-conditioning the “warm side” of the wall in summer is on the outside. How this obvious truth could be overlooked (and why Wisconsin’s building code is still stuck in the past) is hard to fathom, but the building industry has stepped in with a new product—and this is how I ended up on a ladder, wrestling.
CertainTeed’s MemBrain is a 2 mil polymide film that alters its physical structure (!!!) when the relative humidity changes—shifting from Class II to Class III. Water vapor can pass through when humidity is crazy high (60%), but stays “shut down” when humidity is in the normal range. So in winter, MemBrain works like a normal vapor retarder in that it stops warm, moisture-laden inside air from entering a wall or ceiling cavity and condensing on the cold surface of the sheathing. However, should the cavity become seriously saturated, MemBrain will “open up” and allow drying to the inside.
In summer, with air-conditioning running full tilt, MemBrain will stop the warm, moisture-laden outside air from entering the house. But should the cavity become overloaded, it has a chance to diffuse its vapor to the dry air of the interior. Picture a downpour followed by sunny skies. Wood, brick, stone or cement board siding becomes saturated. Solar heat drives the moisture into the building cavity. If traditional poly is used behind the drywall, that moisture will condense and saturate the insulation. With MemBrain, the moisture can pass through.
But many building scientists and high-performance builders say a vapor retarder isn’t needed, except in extremely moist situations like pool rooms and greenhouses, or in homes up north where air-conditioning isn’t used. They argue that vapor diffusion through drywall is minuscule compared to bulk vapor drive through sloppy holes. What’s needed instead is an interior air barrier. Drywall is fine, as long as it’s well-sealed.
Martin Holladay of Green Building Advisor makes an exception for double-stud walls like mine. Because super-thick insulation keeps exterior sheathing extra-cold in winter, the chance for moisture accumulation is greater than in a conventional 2×6 wall. He recommends a vapor-open sheathing like fiberboard or exterior-grade drywall in addition to siding installed on a ventilated rainscreen. Both measures speed drying to the exterior. The other option is to slow moisture diffusion from its source by installing a smart vapor retarder.
My sheathing is plywood, which is more forgiving of moisture accumulation than industry-standard OSB (oriented strand board), but less so than fiberboard. I’ll be installing my siding on DuPont’s DrainWrap, a crinkled version of Tyvek that accelerates drying, but not nearly as well as a dedicated rainscreen. Holladay would say that in my case, a smart vapor retarder is cheap insurance.
While my wall is moisture-forgiving, I’ll bet most of the homes in my neighborhood (built over the last 20 years), are a “moisture sandwich”. Typically, the walls are 2×6 frame with fiberglass insulation and a poly vapor barrier under the drywall with 1 inch of foam over the exterior sheathing. Sheet foam is a good solution for increasing the R-value of a conventionally framed wall, and it really reduces “thermal bridging” but it comes at the cost of trapping moisture. Both foil-faced polyiso and pink or blue XPS are Class I vapor barriers on par with poly. If this wall gets wet, it will likely stay wet for a long time.
My vapor-variable retarder might be cheap insurance, but it’s not cheap. I tried hard to find kraft paper (not attached to a fiberglass batt) that was labeled a Class II vapor retarder, but no luck. I looked at vapor retarder paint, allowed with special permission in Wisconsin, but only found the usual toxic mixtures.
Installing MemBrain wasn’t really too hard. It was more durable than I imagined it might be, and held up to hanging and stretching without tearing. I lapped seams by 12 inches and sealed the perimeter with ChemLink’s DuraSil, a non-toxic, low odor silicone adhesive. In this way I achieved both a continuous vapor retarder AND a continuous air barrier.
Some type of vapor-variable retarder is the only option I’d consider for a smart and sustainable home—given the current level of building science and available technology. But it’s not a hill I want to die on: what will progressive builders be doing in 20 or 50 years? Will my so-called high-performance assembly look antiquated?
May 15: There’s a lot of confusion out there about how tight is too tight. Some builders say a house “needs to breath”, and that sealing every gap is a waste of time. This is how I see it: we all want fresh air. Some of us with allergies need filtered fresh air. What we don’t want is “fresh air” filtered through the building materials in our walls and ceilings. If we leave gaps we are:
1. Wasting energy (losing heat in winter, coolness in summer).
2. Allowing moisture-laden air a route into walls and ceilings, where it can condense on cold surfaces, creating a breeding ground for mold and mildew.
3. Allowing dirty or polluted air a chance to dump dust and allergens into walls and ceilings, or directly into the indoor air.
4. Creating a pathway for insects, or worse—rodents.
In the summer, I can open windows. But in the winter, I’ll need a mechanical system to bring in fresh air and exhaust stale air. Later, I’ll explain the quiet, energy-efficient ducted heat-recovery ventilator (HRV) that will be installed.
Just as I did for exterior air-sealing, I took an enthusiastic approach to interior air-sealing. I used canned spray foam to seal window and door rough openings. It was easy and fast. I’m a little worried about reports I’ve read that foam can crack and separate from it’s wood substrate over time. A bead of caulk or a run of tape over the foam would be prudent, but I haven’t found a way to do that in my particular situation. Where spray foam wasn’t appropriate, I used caulk or tape.
Foam in all its guises is one of the worst building materials for carbon footprint. I chose a low-pressure polyurethane foam called Handi-Foam. It’s a Green Guard Gold product certified for low chemical emissions and is non-toxic when cured.
The electrician has run a few pipes. I sealed those with DuPont’s FlexWrap EZ, a butyl-based peel & stick tape that’s a breeze to install.
With air-sealing complete, the moment of truth arrived—my first Blower Door Test. I’ve arranged for energy auditor Jim Kjorlie of Kjorlie Design Services to come out and test my house three times: before insulation, after insulation and before drywall, and finally upon completion. With his help, I hope to be certified through Focus on Energy’s New Home Program.
Blower Door tests aren’t too common around here, but in neighboring states where stricter energy codes have been adopted, they’re required. Jim set up a large fan in the front door, turned it on, and brought it up to speed. The idea is to depressurize the air to simulate a 20 mph wind bearing down on all sides of the house. Drafts can then be hunted down. Gauges and gizmos spit out numbers—and you either “pass” or “fail”. Here’s how I did, expressed in air changes per hour (ACH)—literally how many times the volume of air in the home is changed out with fresh air each hour:
Wisconsin Code (2009 IECC national code) =7.0 ACH
Focus on Energy New Home Program =3.8 ACH
Test #1 =2.6 ACH
It’s good, but I was hoping for better, like 1.0. Jim went around with a “smoke stick” that detects leaks by showing a trail. Tell-tale puffs shot out at the base and top of the patio door—the usual places, he said. He suspects that the fiberboard vent chute—which comprises 40% of the interior surface area is much more air permeable than the plywood sheathing on the walls. He suggested I find air-perm ratings for both materials, but so far I haven’t found any definitive information.
I’m stoked to bring that number down, so stay tuned for Test #2!
Sunday June 2 from 10 am-6 pm: Progress continues at Spring Green’s first net-zero energy home. Since our last Open House, we’ve completed the roof vent chute, installed the PV solar panels, drywalled the ceiling, started interior wiring, conducted our first blower-door test, and sealed the concrete slab. You’ll still see the skeleton double-stud walls. Look around, meet new people, enjoy refreshments, and ask me questions! Find us one block north of the High School at 770 North Westmor Street. For more information call or text Amber at 608-935-9020.
April 18-28: Icicles sparkling and draping from a roof on a vacay-snow-day is a beautiful sight, but when you know more you see trouble. You see heat loss, hidden pools of water, and stained ceilings.
My super-insulated, super-airtight, super-vented roof will even out and slow down snow melt. Warm moist inside air won’t find a route through and condense on cold surfaces and soak insulation. If I worry about sealing up every single little-bitty gap now, I won’t have to worry about mold, mildew, or rotting structure later.
A flat ceiling is easy to insulate and easy to ventilate. A sloped ceiling like mine takes extra steps. I’ll use eco-friendly cellulose, made from recycled newsprint. But there are two hurdles: it settles and drifts unless “dense-packed” into a cavity, and Code requires it be top-vented to allow any moisture migrating from below a route of escape. The usual solution is a manufactured “vent chute” made of cardboard, plastic or foam—but dense-pack would crush it.
I ordered up a few bundles of 1×2’s and a stack of fiberboard from the lumberyard and had on hand a case of low-VOC caulk (ChemLink NovaLink 35) from Green Building Supply. We air-stapled the 1×2’s to the sides of the top truss chord, fitted in rips of fiberboard, then went back to caulk the gaps and tape the seams. This left us with a 3 inch deep continuous chute separating the roof from the insulation. Any warm, moist air that migrates through will be whisked away, through soffit vents we’ll install in a few weeks.
Fiberboard is an old-school building material and nowadays, a special order. It’s used for wall and roof sheathing, for insulation (R-2.5 per inch) and for sound-proofing. It’s classified as non-hazardous and is recyclable if you can find a facility. It’s made from recycled wood fibers, wax, and usually has a black asphalt coating on one side. It’s vapor-open and sturdy. I could have used OSB (oriented strand board) for slightly less cost and but greater environmental impact. We found the fiberboard easy to work with and not too dusty.
We did a pretty good job with waste, although there were the inevitable cut-offs and caulk tubes that had to be landfilled.
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!