super insulate – Blue Heron EcoHaus

Once you go black…

Posted on September 1, 2016 by kent

We’d really hummed and hawed about what to do about the basement parging for most the winder and early spring. Although our plan had been to do the house all black initially.

HouseRenderHeader

But last year we’d hesitated. And I’m not entirely sure why. We couldn’t run the wood siding all the way to the ground, like the rendering shows, because of the 8” of foam on the exterior basement walls without some seriously extensive strapping. Alas we had the stucco guys parge the basement foundation and then leave it while we contemplated our options: leave it or go all black.

While taking photos for the post about the concrete retaining wall, Darcie, my wife, said, “The house doesn’t look right. It looks like it’s floating. It’s weird.” She proceeded to spend the next several days playing with Photoshop, filling the gray parging with black and analyzing it from multiple angles. After a week of scrutinizing the Photoshopped images, she said, “Look. We should do this.” Pointing to an all black house.

If there’s one thing I’ve learned is that once my wife has made up her mind, it’s best not to disagree. It is only futile afterall. “Yes honey,” I replied (these two words are the most important for a husband to know, by the way).

So I called the stucco guys and asked them to come back. It ended up taking a number of weeks for them to finally show up (typical). But only a couple hours for them to transform the house.

I gotta say, I don’t know why I’d hesitated, because once your go black… well, you know the rest.

Musings on Passive House Standards and the Costs of New Home Construction, Part 1

Posted on February 24, 2016March 5, 2016 by kent

A friend of mine sent me this article for Tree Hugger yesterday about an Irish county that made the Passive House standard for all new home construction. This is a pretty big deal. The question then came up – why doesn’t Canada (or the USA) adopt such strict and stringent standards to their new home construction? Certainly the Paris Climate Conference of 2015 has finally made it official what everyone and their dog already knew: the world is overheating and we need to do something about it before we all die. Building better homes could make a massive difference in our world’s energy use. It is well-known that a certified Passive House uses 80-90% less energy than a standard house.

The problem, as usual though, in making such rigorous standards mandatory is a combination of bureaucracy, status quo, and resistance to change. In this post and my next, I will make the argument that I believe there is a skewed perspective on both sides of this battle in Canada.

Did you know that the minimum standard for wall construction in Saskatchewan (a province that has frigid winters of -40° temperatures for long stretches and over 10,000 heating degree days per year) is a 2×6 wall with batt insulation? The effective R-value of this wall is only R17.5 due to thermal bridging (as the wood studs bridge between the inside and outside of the wall). This standard must be out of date, you say? In fact, this was recently upgraded to this absurdly pathetic level in 2012 (it was only a 2×4 wall before that). Shameful.

As if this wasn’t bad enough, most homes in Saskatchewan feature R12 in basement walls and only R40 in the attic. There is no requirement for insulation under the slab of the house. Also, the building code requires only double-pane windows – such insufficient windows account for a massive amount of heat loss of up to 50% (these are usually vinyl framed windows, though sometimes wood or aluminum). And placement of these crappy windows can lead to further issues with heat loss due to inadequate southern exposure and large windows on the north side of house. Furthermore, air leakage rates in most new homes is about 2.0 ACH@50pascals (which is actually one of the lowest values tested in Canada). (Source: Energy Standards by Ken Cooper)

I assume that you can get the picture that our homes are generally very inefficient (don’t think that this is specific to Saskatchewan – this is relatively consistent across North America).

Although we did not build a Passive House, we followed the principles of this as closely as we could financially justify (which is the rub, more on this in my next post). For a quick comparison, our house has R56 walls, R80 attic, R32 basement walls and under-slab. Our latest air tightness test was 0.72 ACH@50pascals (and with some extra tightening we’re hoping to get this to 0.65 or less at the next test). We used triple-pane fibreglass windows. The design of the house maximized heat gain through the south windows and minimized heat loss through the windows on the east, west and north sides. Passive shading with our roof overhangs prevents overheating in the summer. The positioning of the house is directly south (a luxury we have living on an acreage). We also installed PV panels to offset our meagre energy use, which are becoming more and more affordable.

Now, a lot of people wonder and ask (I know I did prior to building), that it must cost substantially more money to build a house to this level of efficiency?

The simple truth is that it does not have to.

The general consensus is that a new custom home in Canada, excluding the cost of purchasing land, is between $200 and $300 per square foot to build (a contractor spec “cookie cutter” home built to the minimum standard with minimal features and cheap finishing can be $175/sq.ft or less). Indeed this is large range – for a 1500sq.ft home you could either spend $300,000 or $450,000. But for argument’s sake, let’s say $250/sq.ft is a realistic cost of a new custom home (we will also assume that most people would not build to the bare minimum construction standard of a spec house and see the benefit of adding triple pane windows and a 2″ layer of EPS foam on the outside of their 2×6 wall).

OK so where are the extra costs?

I would say that the design planning and orientation of the house will be the single biggest factor in determining your initial and long-term costs in a high performance, energy efficient house. It does not cost anymore to build a house with your windows facing north instead of facing south. Positioning the long side of your house to east does not cost anymore than facing it south. Designing correct overhangs for shading does not cost anymore than designing insufficient overhangs. Designing outcroppings, bay windows, and cantilevers does not cost anymore to design than a rectangle or a square-shaped building. Placing operable windows appropriately for cross-ventilation does not cost anything extra either. But all of these decisions and factors can have huge ramifications on the cost of construction and/or long-term costs of operation. We had several team meetings during our design process (including a Passive House certified designer, contractor, and LEED engineers) to decide on which systems would be best suited to be optimally energy efficient, be comfortable to live in, and also to make sure everyone, including sub-contractors were on the same page. This extra consulting time accounted for 2.5% of our overall cost.

In terms of actual construction costs, we built a double 2×4 stud wall that is 16″ wide. The cost of materials for this wall system versus the cost of 2x6s and the 2″ of EPS foam is almost negligible. Framing labour costs were slightly more though as each exterior wall was built twice (accounting for an additional 2% of the overall budget). Remember though our design is simple, a rectangle, meaning four walls – no bays or outcroppings. We also invested 20% more in purchasing fibreglass framed triple-pane windows versus the usual vinyl or wood triple-pane windows (accounting for an additional 1.75% of the overall budget). Insulation costs slightly more but pays for itself in short order when compared to long-term operation costs (the upfront cost is an additional 2% of the overall budget). Airtightness of the house did not cost us anymore than the standard vapour barrier (although it does require some attention to detail by the tradespeople) with the exception that we needed to install a heat-recovery ventilator which cost $1200 (0.3% of the budget).

But there are also some possible cost savings to consider. One can get away with a smaller mechanical heating system due to the lower heat load required in a super-insulated and airtight house. For us, our mechanical system cost about the same as a standard house due to us deciding to install in-floor heating and a wood burning stove. Although you certainly could get away with baseboard heaters or a very small forced air furnace combined with a heat coil on your HRV if you so chose (for us we wanted the in-floor heat and a wood stove – you can read about our reasons for this here and here). Most new houses also have air conditioners installed. We do not (cross-ventilation, insulation and proper shading is all that is needed).

The bottom line is that it cost us about 8% more to build a house that is in the range of 75-80% more efficient then a standard new custom home.

After these extra costs are accounted for the rest of construction costs are basically the same as any other house – how much do you want to spend to finish the house is based on your taste and how much you want to invest in your bathroom fixtures, lighting, hardwood flooring, custom cabinets (vs. Ikea), appliances and so on. Also, how much sweat equity do you want to do yourself? All of this will have a big impact on your end costs (consider, painting our house took 5 full days, but saved us about $6,000+. Installing the tile in the bathrooms and kitchen ourselves took 10+ full days, but saved us another $8,000).

Ok, so you’re probably thinking, how much did this damn house actually cost you? Tell me already! Although I haven’t done our final-final tally yet, it is in the range of $280/sq.ft. But this also includes the cost of our 6.2 kW solar PV system, our septic system, and the cost of trades to travel the 30 minutes to our house each day. Removing these factors, to build the same house in an urban area, you could easily do it for $250/sq.ft.

Say… that’s pretty much the same as what we said a typical new house would cost, right?

So why the heck isn’t everyone doing this??

Well, it goes back to the fact that there is an unfounded assumption that building an energy efficient house costs a lot more (I think we’ve shown that it simply does not have to). It also does not help that energy costs from non-renewables such as coal-fired electricity and natural gas are very cheap still (even so, those extra 8% in building costs for us should be paid back in less than 12 years in monthly energy bill savings). And the public outcry for action is not yet greater than the apathy of maintaining the status quo on the part of our government, the building industry, and those contractors who have been making a tidy profit on their suburban sprawl spec houses.

Part two to come…

Observations, expectations, and regrets

Posted on February 20, 2016February 20, 2016 by kent

As I’ve written about building our house over the past 18 months or so, I’ve commented several times that the decisions we were making in energy performance and efficiency of the house were all theoretical. Certainly, we based our decisions and assumptions on solid foundations of research, well-established protocols, software design and modelling, and the recommendations of others who have built high performance buildings or through websites and blogs of others. But STILL. I couldn’t be sure how the house would actually function. How efficient would it be? Would we overheat? How much solar power would be generate? What are our power bills going to be? How comfortable will we be? Oh and of course, do we have any regrets? These were all questions on move-in day that we had yet to answer.

Here are some observations from the first three months of living in the house.

We have had an unseasonably mild winter this year including several days of above freezing temperatures in January and February, which generally are our coldest months of the years. In fact, the past 5 days have been between +1°C (34°F) and +6°C (43°F). Normally the ice from the river is not breaking up until mid- to late March, but just yesterday it’s already opened up (#globalwarming).

But even so, we have had a few of our more typical extremely cold days too (we couldn’t get off this easy of course). In December we had a couple days of -40°C (-40°F) or colder. One of these days was a bright and sunny Saturday, the news here reported that it was the highest day of power usage across the province for the year. Our dogs were lying in the sun panting and the temperature on the thermostat read 24°C (76°F) – without the boiler running – purely from passive solar heating. I had to laugh. We even had to crack a window for awhile so we didn’t overheat.

warmday

Even though that day was great to see how well things performed under extreme conditions (very cold day + lots of sun = no active heating required. Awesome) I was a bit worried that we might overheat on milder winter days with lots of sun. But, for whatever reason, this really hasn’t been the case. Within a few days of that extreme cold snap, we were back above freezing temperatures with lots of sunlight. I think a couple days it did creep up to +26°C (+78°F) on the thermostat due to passive heating, but with our well-planned operable window placements, we could simply open a window or two and cool things down if needed. It seems bizarre to me that I’d need to open a window in the middle of winter, but it really does not bother me to do it. But it also makes me very happy (and relieved) that we really thought out well how to get good cross-breeze ventilation throughout the house (although we thought this would be for summer passive cooling not the winter too!). If we didn’t have this I might be cursing myself due to overheating issues.

All this being said, of course, on cold and cloudy days, the boiler and in-floor heat runs. We have it set to keep the indoor temperature at 20°C (70°F). We played around a bit with what setting to keep it at – going as high as 72°F (comfortable all the time, but easier to overheat with passive heating, also running the wood stove would make it too warm) and as low as 68°F (too cold in the morning, even with a sweater on, and needed to be running the wood stove morning and evening). We both wear a sweater in the house in the morning – cheaper to put a sweater on then to pay for more power. If it is really cold out then I light a fire in the wood burning stove, which is a nice luxury to have. When we tried setting a lower temperature in the house, I was needing to light a fire every morning, which was a hassle and not something I was overly motivated to do every day.

I’ve started tracking our solar generation through our 6.2 KW ground mount PV system with the plan to monitor this for the year. This time of year makes for the least amount of solar generation due to the short days, more cloud cover, lower height of the sun in the sky, and SNOW. I’d not really considered it before but snow and ice covering the PV panels is crazy frustrating. I guess I assumed the snow would just fall of it. Not so. The first couple of times this happened I shouted out in horror – we had a bright sunny day, but due to a snowfall in the nighttime our panels were 100% covered! I grabbed a ladder climbing up to clean the panels with a broom – an arduous task with the wind blowing and -20°C (-4°F) temperatures. There must be a solution to this I thought, but after reading several websites, it seems like the only solution is a long broom handle or to wait for the sun to melt it off. This was so aggravating – seeing our energy generation oppurtunities being squandered. Aside from a 16′ long broom handle, I’ve not yet found a good solution to this problem (and perhaps there is no solution).

I’ve also started tracking our energy use, but this has been more difficult as we have an outdoor chicken coop with a heat lamp and a water heater that is on 24/7. These suck energy like crazy. I’m sure these three chickens are costing us a fortune right now (they better start laying golden eggs) – in fact, I think heating their little 24sq.ft coop is more expensive then heating our 1240sq.ft. house. So for this year we will see what the total energy use. But for next year, we have a second transformer located next at our shop (and not connected to the PV panels), so I will try to run the chicken coop power from there, which will give us a more accurate reading of the house’s energy use for 2017. (I also need to build a passive house chicken coop now).

I guess the last thing that everyone seems to ask – which is interesting as it is one of the first things they ask after, “So you’re all settled into the house?” … “Any regrets?” or “Anything you would change?” To be perfectly honest, my answer is, “No. Nothing.”

We really love the house. We love the design. We love the style. We love it’s performance. We love the comfort.

We spent a lot of time planning, designing, and researching the house. We did not compromise and we followed the adage to: “Do it right the first time.”

I have no regrets.

Basement concrete slab

Posted on July 25, 2015July 25, 2015 by kent

I do love concrete. It is one of those rare man-made products that border on being a living thing, like plaster or linen. Those things that have such a rich texture and variation of composition that they seem to beckon you to touch them and get up close for a better look.

Of course, not everyone will share my appreciation of concrete, traditionalists have tended to cover up the concrete or at least extensively treat it with stains and dyes making them more palatable to themselves. Not us. When I told an interior designer about our exposed basement concrete walls, his response was, “Now that’s modernism with a capital ‘M’!” Cool, I said, “What’s modernism with a little ‘m’?” To which, he sheepishly did not have a response (I’m an ass).

After the walls cured for 28 days, we had to seal the concrete. We wanted to get this done before the slab went in because if we waited to do the floors and walls at the same time, not only would there be framing and drywall in the way, then we ran the risk of the drywallers slopping crap all over the walls and making a mess of our beautiful concrete finish. Like an idiot, I decided not to purchase a $25 dollar wand sprayer to apply the sealant and instead decided to use a nap roller. A job that would have taken me 30 minutes ended up being closer to 5 hours rolling every inch of the wall on multiple passes (lesson learned).

Next, we had to lift the giant water tank and Japanese soaker tub off of the floor and strap them to the steel beams (getting the tub in the basement was another adventure in and of itself. I will write about that someday). The under slab insulation was then cut and laid. We elected to use 7.5″ of under slab insulation, which is likely overkill, however this brings the floor insulation to R30 (our last house had no insulation in the basement at all). This EPS insulation was pretty cool. Having a honeycomb pattern as the top layer allowed for incredibly easy installation of the PEX piping for in-floor hydronic heating.

Notice the levitating water tank and soaker tub

We knew we wanted the concrete floors to be a simple natural grey concrete, power troweled and sealed to complement the exposed concrete walls. No fancy finishing, dying, staining or grinding.

Now being that the basement concrete slab was to be our finished floor, it was pretty important to me that it not look like crap. Therefore the quality of the contractor needed to be top notch. Unfortunately for us, that was not how we entered into this venture.

I did not meet the contractor before he was actually on site prepping to pour. My wife had driven home early that day and came upon a most peculiar sight. A rather criminal-looking fellow standing beside a broken down early 1990s sedan, holding booster cables. Our place is a bit out of the way, so this was not a sight one would expect. Of course she stopped to see what the problem was (as the next passerby would probably not be until much later on). He proceeded to tell her that he needed a boost, he’d gotten in a fight with his boss and left from “that house being built down there”, pointing in the direction of our house. My wife, boosted his junk car, and asked if he was going back to work? Nope, he said, and drove off.

My wife drove to the site and found a lone guy working in the basement – no truck, no car, no nothing. She told him she might have just met his worker on the road and asked how he was getting home. Of course, he had no idea. She called our general contractor to come pick him up, however as she was leaving the property his buddy had returned with the car.

When I stopped by later to check on the whole situation, they were still there. “Working late, boys?” I asked. “Yup,” the boss said, “but we gotta get home, we’re losing light and we don’t have any headlights.” (He wasn’t joking).

He told me that they were planning to have the concrete poured in two days, but would need to finish laying the rebar and tying everything in beforehand. “I’ll be back at 6am tomorrow,” he said, before driving off headlight-less into the night. I came by the house at 7:30am and, not surprisingly, they were not there. Sometime throughout the day however, they were back working away in the basement – this time, they’d brought a rusted old Honda, apparently this one had headlights and was more reliable.

On the Thursday, which was the day of the scheduled pour, they did not show up at all (what other profession could you simply not show up to work and there be no repercussions?). The bossman called our general contractor later in the day, apologizing and saying that he had to fire the criminal looking guy, but promised to complete the pour the next day. I told the contractor that it was tomorrow, or else he was off of the job.

On Friday, I received a phone call from them telling us it was “too hot” to pour the basement slab. Granted it was 34° Celsius. He said that the concrete would cure too fast and they would not be able to guarantee a nice finish. I wondered to myself – is this a convenient excuse for them in case the floors didn’t turn out? What am I to do? Ask them to pour it anyways? I called a couple of friends that I have in the concrete business and asked if they were pouring today. They were. I asked if there would be any reason to not pour a basement today and they told me that an insulated basement would be perfect in this weather – being at least 10 degrees cooler in there and not in direct sunlight.

That afternoon, we made calls to find a replacement for this retard concrete guy. I couldn’t handle it anymore – how many chances do you give someone? That being said we needed the floor done immediately. This idiot had already setback three other trades with his 5 day delay. Especially when Taylor and Curtis worked to hard to be ahead of schedule despite some of the challenges they faced with the Nudura One set up.

Incredibly we talked to Tyco Concrete Finishing, who said they would be able to squeeze us in early the next week. That Sunday evening we met the owner on site (I was relieved to see him drive up in new super duty 4×4 truck). He spent a couple hours with us going through everything, including checking what little work the other guy had done, making sure he knew how we wanted it finished, and confirming all of the dimensions and depths.

Two days later this was happening:

They had a crew of six guys on site and they did an awesome job. That night we came home to this.

Water Tank and Foundation Finishing

Posted on June 21, 2015July 21, 2015 by kent

We finally decided at 1pm on Monday that we were going to do the water tank in the mechanical room. We had went and viewed our neighbours set-up and talked to him about his experience. It all seemed good enough. But meanwhile that morning, the crane had shown up and lowered the giant steel beams into the walls of the foundation.

I had watched the crane go to work in awe like a little kid – “Woah, a crane!” It was pretty awesome to see the crane towering over our trees and lowering the steel beam into the grooves that Taylor and Curtis had left when pouring the concrete a couple days earlier.

It was an impressive sight to see. The slid in so effortlessly.

Within a few hours, the guys were hanging the joists and starting to the lay the floor. You’ll notice that the beams and all of joists are within the envelope of the foundation walls. This was intentional from an energy efficiency point of view. There is no thermal bridging at all with this system. Oftentimes typical houses are built with the joists sitting on top of the concrete wall or on a ledger of the wall. Both of these are a bit more work then simply using hangers. And the former, requires excessive use of spray foam to seal.

The way we did it required a taller basement wall, but there is zero chance of air leakage, thermal bridging or heat loss with this.

Anyways, the carpenters were working fast. Crap, Darcie and I realized, we had to decide immediately whether or not we were going to have the water tank in the basement. The carpenters were going to be done the floor system the next day, which meant that the tank needed to go in the basement NOW.

I made some calls and found a manufacturer east of Saskatoon who sold large tanks. We hopped in the truck and made the 45 minute drive. We had debated briefly about what size of tank to get – essentially everyone we talked to told us to purchase the largest tank that would fit in the house. That meant we could get a 2100 US gallon tank – measuring 88″x88″. If you can’t picture that, well, it’s big.

We drove back to the land and within a couple hours were ready to haul the giant beast of a tank into the basement…

Only problem was the crane was long gone, and there was a huge gorge – 11′ deep and 6′ wide – all around the perimeter of the house. The four of us put our heads together. We all agreed this would have been a LOT better to have done when the crane was here… Crap.

The options were slim. The only possible way was to jimmy up a rickety makeshift bridge between the foundation and the ground using 2x10s and some left over joists. We decided to push the tank off of the trailer (there was no way to carry it) and roll it to the side of the gorge. From there we wrapped two large ratchet straps around the top of the tank and lashed them to the back of my tractor.

Now came the dangerous part – Taylor and Curtis pushed the tank onto the shoddily crafted bridge (one false step would mean certain death or at least dismemberment) while I slowly backed up the tractor thereby keeping tension on the straps and allowing the guys to ease the tank across the “Bridge of No Return.” My wife cringed as she watched the bridge bow under the weight of the tank and guys.

Miraculously no one was killed. Not even a little bit.

Once we had the tank to the edge (Taylor had also built a small ramp on the inside of the foundation), I could simply back the tractor up and lower it down.

That went well.

By the end of the day, the guys had the floor framed – pretty impressive. They’d poured the basement on Friday and floor was framed and sheeted by Wednesday. Time for a dance party.

We all grabbed a beer to celebrate and as we were standing there, an eagle flew by carrying a fish. We were all in awe and Curtis said “and this is where you guys live?”! It was awesome.

PS. One more geek/nerd energy efficiency thing: They wrapped the house in the water proofing seal, but also wrapped it up and around the plywood to create a complete seal around the entire basement. It is possible that a small amount of air leakage could occur through the plywood and the top of the joists and foundation wall. This simple trick tightens the house up even more.

Foundation/Basement Forming

Posted on June 11, 2015June 11, 2015 by kent

Meanwhile, the foundation work continued to move forward. A few weeks ago I’d written about the Nudura One Series of ICF. We were quite excited about it for a number of reasons. Firstly, basements are generally BORING. So, with using this system of ICF we could have a finished interior wall of concrete immediately, which would look aesthetically pleasing and be something of interest and uniqueness in the basement. No need for any extra framing and drywall. Second, in terms of energy efficiency, this system should perform better than conventional ICF. You are not insulating the walls of the basement from the house itself (standard ICF and standard poured basements have insulation on the inside and cannot use the thermal mass of the basement walls). Being that we have a huge thermal mass in the walls (and floor) of the basement, they can store a lot of heat to radiate to the rest of the house either through sunlight or simply from the in-floor hydronic heat. Essentially functioning like a giant battery.

About a week prior the forms had been sent out. There was an incredible amount of insulation that was stacked in the shop.

And the day following our stresses with the septic system, Taylor and Curtis got to work building the basement forms. They had budgeted about four days to get the forms up and one day to pour. ICF goes fast, they said.

… But not this ICF. This basement was a massive pain in the ass. After one day, the guys only had one row of the seven done. There was no simple way to attach the forms and keep them locked in place. You see, in standard ICF, the blocks are basically like Lego. There are little grooves on the inside and outside that line up and attach to the corresponding little plugs on the other block. Snap snap snap, it goes together. Easy.

This was not easy. The little Lego grooves and plugs were only on the outside of the blocks. Not the inside, as the plywood slabs simply butted together creating big seams and gaps (wouldn’t tongue and groove plywood have made sense, Nudura!?). Frustrated at the lack of progress, Taylor called the Nudura sales rep who came out to the site. Amazingly, he had never seen the Nudura One series before. Like never ever. As they all worked together to try and troubleshoot this problem, they eventually decided to call the head office in Ontario, Canada and their technical support team.

They suggested make 2×4″ L-brackets to support and anchor the forms (uh, that’s part of the plan?). Oh and as for the gaps in the plywood? (Where concrete would completely burst from when pouring.) Well, just use Tuck Tape, they said. Tuck tape!?? (I suppose it’s slightly more classy then duct taping the forms). Jeez Louise.

Unfortunately, after building a bunch of the 2×4″ L-brackets and bolting them onto the forms, the carpenters realized that this was not going to work at all. These brackets did nothing and if anything made the problem worse by pulling the forms further inwards, causing even greater warping of the walls. Thanks for the “technical support”!

(You’d think they’d never sold this product before – which, later we found out they have never actually used it in a residential application!)

Over the following four days, Taylor and Curtis grudgingly put the forms together and stacked them higher and higher, eventually reaching the top at 10’6″. They put an absolute tonne (perhaps 2 tonnes) of rebar in the ICF both vertically and horizontally to reinforce the high walls and provide the structural support for the beams, joists, and double wall that would sit upon it. Seeing the forms go up was pretty exciting, but just don’t look too closely or right down the line of the wall…

Because that ain’t straight.

I have to admit, I was more than a bit worried. How the hell were they going to straighten these walls? I wondered.

Taylor and Curtis had also eaten through their projected timeline and still had to try to straighten the walls. After four days the walls were not even stacked, let alone straight and ready for concrete. Over another three days, all they did was straighten and adjust the walls. Using large bracing and strapping to make them level, straight and even. When Taylor finally told me they would be pouring concrete the next day, I had to run over and make sure.

Praise Jebus! (This whole process is making me become very religious it seems.)

The following day the pumper truck was out, pumping a buttload of concrete into the basement walls. Now was the real test of the untested Nudura One walls and the Macgyver skills of the build team.

I was nervous that day at work, just waiting for the phone call from Taylor explaining that there had been a catastrophic failure when the walls of the forms burst under the pressure of the concrete causing the walls to break apart and concrete to fill our basement.

But that call didn’t come. Relieved, we drove home at the end of the day. The walls were still standing and they were filled to the brim with concrete!

The next day we would pull the plywood off and see what magic laid beneath.

PS. Nudura has offered to cover at least some of the extra time of the build team for Research and Development of the Nudura One series.

Choosing a super-insulated wall system

Posted on November 1, 2014 by kent

After deciding on the mechanical system of the house we needed to choose what type of wall system we were going to use. As I’ve learned, for an Eco-house, there’s more than one way to skin a cat! (who came up with that saying?!) Again, it was a matter of weighing the advantages of each and ensuring that our contractor felt comfortable with whatever system we decided on.

Passivhaus tends to utilize a double-wall system, although there is no set way to do this, as long as you meet the Passivhaus criteria.

This method is nothing new, there are many houses from the 1970s that utilized a system of a 2×6 wall at 16″ on centre (o/c) and offset with a 2×4 wall 16″ o/c for an interior wall. Nonetheless, biggest concerns in ensuring an exceptional envelope of a Passivhaus or any other super-insulated home is: thermal bridging and airtightness (and to a lesser degree the overall R-value).

Thermal bridging is basically an easy pathway for heat to flow out of your home. In a conventional single 2×6 wall, this happens every 16″ as the 2×6 piece of wood is connecting the inside to the outside with out a “thermal break”. This is why a R19 insulation in a 2×6 house actually has a lot less R-value.

Airtightness is how leaky is your house? While thermal bridging can be limited by proper construction design. Airtightness can really only be ensured while on-site building the house. Airtightness is tested with a blower door test and is rated based on “air changes per hour a 50 pascals of pressure.” As previously mentioned, Passivhaus standard is 0.6 ACH. The Canadian R2000 is 1.5 ACH.

R-value is of course also important, but less so than reducing thermal bridging and ensuring excellent airtightness. This is because R-value is a rating of the “effectiveness of insulating materials.” You could have an R50 house, but if it is leaky and has thermal bridging it will not function like a “true” R50 house.

In the last 10 years, there have been numerous high-performance, high-tech wall systems that have been developed such as Insulated Concrete Forms (ICF – concrete poured into thick pieces of foam) and Structured Insulated Panels (SIPs – OSB laminated to the inside and outside of a big piece of foam), both of which eliminate thermal bridging altogether by not utilizing timber at all.

Passivhaus’ use a variety of options, though many that I’ve read about use some form of double-walled systems often with SIPs on the outside and 2×4 timber framing on the inside. An 8″ thick SIPs panel is about R33 on it’s own so add that to the R11 of a 2×4 wall and you get a well-insulated house with minimal thermal bridging.

We had already decided that we would be best served, given our rural location and 55km distance from town, to pay our contractor to be at the site working – instead of driving back and forth with lumber. As such, we wanted to utilize a company that could provide either a prefabricated wall systems (which could be erected very quickly on site) or a “kit” (all of the wood cut to size to be put together like a model). Because we have a large shop on site, the materials can be all shipped at once and stored inside. Also, this significantly reduces onsite waste and chance of error.

One of the companies we looked at was Pacific Homes out of Victoria BC, who our builder has worked with on previous projects. This company produces a “Smart Wall” system – a prefabricated timber wall that eliminates thermal bridging and significantly increases R-value. A standard 2×6 wall is R19. The 2×6 Smart Wall is R31.

We compiled a list of “attributes” for each option that we felt were most important in our decision-making process:

– R-value

– Airtightness

– Ease of construction

– Construction labour time

– Material waste

– Total cost (time/money/energy)

Options for walls were as follows:

1. Pacific Homes 2×6 Smart Wall with 4″ of rigid foam (EPS) on the outside.

This option was appealing due to it’s low cost and simplicity. However that simplicity quickly got tossed as we are quite certain that we want to use cedar siding on the house. Trying to secure cedar siding to foam is not possible without significant strapping and labour to ensure everything is kept in place. This would work for stucco, but it would not be ideal for us. R-value of about R45. Airtightness might be less than other options given that this is really a single-wall system.

2. Pacific Homes 2×6 Smart Wall with offset 2×4 standard wall at 16″ o/c.

This is a simple option as well. The outer wall would be prefabricated and shipped. Given the prefabrication, the house could be framed with roof, windows and doors installed in 2 weeks (same as option #1). The internal framing could be done after and standard cellulose batts used inside. The good thing about this over the first is that the plumbing and electrical would not pass through the 2×6 outer wall therefore eliminating potential air leakage. The cost of this one was quoted at about $5000 more than option #1 due to the extra 2x4s and insulation batts. R-value for this was R41.

3. 14″ thick ICF

ICF uses styrofoam forms with concrete poured into it. It’s appealing for a few reasons: no thermal bridging, super strong walls (disaster protection), has a good R-value (R48) and is naturally airtight (expect in the corners and around openings which of course need to be sealed like any other system). It’s a bit controversial though and quite a bit more costly in terms of time, money and energy. It is a labour intensive project and we simply did not think it would be worth it in our case.

4. 8″ SIPs with 2×4 standard wall at 24″ o/c

SIPs are touted as an energy conscientious option that can be installed extremely quickly. A 2000 sq.ft house can be erected in two days. SIPs uses two sheets of OSB laminated to a slab of EPS foam. It is very strong and does not require further framing. The R-value of an 8″ wall is R33 so combined with a 2×4 wall at 24″ o/c you get R44. I thought this would be a pretty excellent option. SIPs are only marginally more expensive then a standard wall system (and when you factor in the reduced labour cost, it is negligible) and are quite a bit less than ICF. Unfortunately, SIPs have been found to have some pretty serious problems with moisture build-up, airtightness problems, and early decay. None of those sounded good to me. Sorry SIPs, not for us.

5. 16″ Deep Wall System

One of the engineers on our team had worked with a group from Edmonton AB who utilized a “Deep Wall System.” I had never heard about this, but was intrigued.

Deep Wall System – Mill Creek Net Zero House, Edmonton AB

Essentially this uses a 2×4 wall 16″ o/c on the outside and 2×4 wall 24″ o/c on the inside. A 3/8″ thick piece of OSB is cut 16″ inch wide for the header and footer. The 2x4s are spaced and secured to the headers and footers with a 3/8″ OSB sheet on the outer wall. Essentially you make a box with a mesh on the inside. The 16″ cavity is filled with blown in high density cellulose. This gives an incredible R-value of R56! As if that’s not impressive enough, the material cost of building is about the same as a standard 2×6 wall (not including cost of extra labour time for framing mind you). The airtightness on the Riverdale NetZero house was 0.59 ACH and the Mill Creek NetZero house was 0.36 ACH. Amazing. As I later found out, the energy guru and one of the creators of the Saskatchewan Conservation House (the house that inspired Wolfgang Feist and led to the German Passivhaus Institut), Rob Dumont, developed and used this exact method on his house in Saskatoon SK. He built his house in 1992 and at the time was considered to be the most well-insulated house in the world (the airtightness was also an incredible 0.47 ACH). Why didn’t they just tell us that in the first place!? There would have been no decision-making necessary. We would have just done what he did. We will still have a company cut all of the lumber to size and ship as a package. Although this system will take a bit more time to complete (due to framing labour) the advantages of this wall system for us far exceeded the other options.

I’m super excited for our super-insulated and locally developed wall system.

-K