Archive by Author

Goodbye to the class of 2014

The students of the Sustainable New Construction 2014 class said a belated goodbye to Endeavour and the teachers’ union office project.

Their departure was one month later than expected, as five of the seven stayed on through October to make up for time lost during permitting issues earlier in the summer.

The last week was about adding some fun finishing details to the building, including the cordwood entryway to the meeting room and some great bottle and hempcrete transom details in the doorways.

This was an amazing group of builders, and we wish them all the best as they move onto their new lives in the sustainable building world!

Thinking about sustainable building

There is a remarkable paradox when it comes to introducing new technologies, in construction or any other field. We expect new ideas or technologies to live up to unrealistically high standards, while at the same time we accept as normal many existing ideas or technologies that are inherently, deeply flawed.

It is a commendable tendency to try and be “objective” about new ideas and weigh as much evidence as we have at hand in deciding whether or not we think they are worthy. But we tend to be much less than objective about the ideas and technologies we use on a daily basis. Because they are normal to us, we rarely examine them in any meaningful way. A certain degree of inevitability is attributed to the ideas we’ve normalized; we don’t see them as choices in the same way we see new ideas as choices.

There are countless examples of this paradox in everything we do. In the building world, we find a great example in the use of milled lumber as our prime residential building material. Wood has every flaw imaginable for a building material. It burns; it rots; it’s insect food; it warps, twists and cracks; it’s a great medium for growing mold; its structural properties vary greatly by species, milling, drying and storing practices; it’s often grown far from where it’s needed; it’s heavy; it’s dimensionally unstable as climatic conditions change…. In fact, if an attempt were made to introduce wood as a building material in today’s building code climate, there is little chance that it would ever be approved!

And yet milled lumber has come to serve us very well as a building material. Collectively we used a natural material that was available to us and figured out how to deal with all its “micro-flaws.” In the end, we’ve normalized it and built an entire successful industry around an entirely flawed material! But if we introduce a new material that has even a small number of the flaws inherent in wood, we find ourselves up against naysayers who can only see the flaws and not the possibilities for being able to work with them. Straw bale and earthen building techniques can have many fewer flaws than wood construction, and yet are subjected to much more scrutiny.

There is no such thing as an idea or technology with no flaws. Recognizing this simple point is key to being able to consider new ideas fairly. There is an experiment I perform at public talks: I ask the audience how many of them have had to deal with a toilet backup at some point in their lives. The show of hands is almost guaranteed to be unanimous. Then I ask that same audience if they think the flush toilet is a bad, flawed idea that ”doesn’t work”; very few say Yes. And this despite having to regularly deal with some very unpleasant consequences due to an inherent flaw in the technology! We accept the micro-flaw of an occasional toilet backup as a reasonable trade-off for the convenience of using a flush toilet. However, I hear frequently that composting toilets “don’t work” based on second-hand reports of a single incidence of the composter smelling or not composting properly. There’s the paradox: the “normal” technology fails disgustingly at a rate of almost 100 percent, and yet the “alternative” is the one that gets branded as something that “doesn’t work.” In truth, both systems have some inherent flaws, and both will fail on occasion. We’ve just learned to accept the micro-flaws of one and reject the micro-flaws of the other.

Can composting toilets work? It's a question worth putting your head into!

Can composting toilets work? It’s a question worth putting your head into!

 

Every new technology a homeowner will examine when making choices has a number of micro-flaws, as do those conventional technologies they might replace. One should not attempt to gloss over any micro-flaws, as you will be living with them for a long time. But the comparisons between sustainable technologies and their conventional counterparts do not and cannot stop at the level of micro-flaws. Sustainable building strives to address the larger and much more important macro-flaws in our approach to building.

It is at the macro level that all of the materials in this book have their advantages over conventional practices. To continue the comparison between flush toilets and composting toilets, we can see that both can be practically functional but also have some micro-flaws. On the macro level, however, the flush toilet is part of a system that sees billions of gallons of untreated or partially treated sewage enter our streams, rivers, lakes and oceans, while using vast amounts of clean potable water and a very expensive public infrastructure. Meanwhile, composting toilets can turn human “waste” into a valuable fertilizer with minimal infrastructure and little to no fresh water usage. It is at this macro level that we should be assessing our building technologies. In this case, the advantages of the composting toilet should be very clear.

Sewage report card

If we can start making wise choices at the macro level, we can trust ourselves to figure out how to minimize the micro-flaws of any technology. We humans are incredibly good at refining ideas and techniques. Through repetition, we gain insights that allow us to make the process better and better each time we use it. We’re good at doing things better, but we’re not very good at doing better things. Doing better things means looking beyond the micro-flaws and basing our choices on minimizing impacts at the macro level.

One of the challenges in adopting any new technology is figuring out where we are on the learning curve, and at what point on that curve we feel comfortable jumping on board. Some of the systems we work with in sustainable building are quite well developed, with installation and maintenance instructions that are very complete and manufacturer and installer warranties that back them up. Others are relative newcomers (at least in the modern context) and the instruction manuals are literally being written and refined right now. We may not know the very best way to use some of these systems until a lot more early adopters have trial-and-errored their way to some kind of standardized practice. There are rewards to helping break new technologies, and also risks.

Figuring out what choices to make in a sustainable building project can be overwhelming. It requires a lot of level headed research, a willingness to question in cases of 2G2BT (too good to be true), and a clear understanding of your goals and your budget. Endeavour’s Plan Your Own Sustainable Home workshop is a great way to start sorting out all these choices for yourself!

(This blog is adapted from the book Making Better Buildings: A Comparative Guide to Sustainable Construction)

Making Better Buildings book by Chris Magwood

Making Better Buildings by Chris Magwood

Building with Hempcrete or Hemp-Lime

A group of lucky participants was treated to an excellent weekend workshop on building with hempcrete (or hemp-lime), led by UK architect and hempcrete pioneer, Tom Woolley. Tom is the author of Hemp Lime Construction and Low Impact Building, and has been involved in many hempcrete and sustainable building projects throughout the UK.

The weekend began with a classroom session, during which Tom covered the materials and techniques for successful hemp-lime building, and showing the group photos and details of a variety of building projects, including his charming hemp-lime cottage.

We then moved on to making some sample mixes to demonstrate the combination of materials. We were working with two different mix types, and made a sample of a third type of mix. For all three mixes, the weight ratios of materials were the same:

  • 1 kilogram of chopped hemp hurd (also known as shiv)
  • 1.5 kilogram of powdered binder (natural hydraulic lime or hydrated lime and metakaolin)
  • approximately 1.5 kilograms of water

The chopped hemp hurd or shiv needs to be fairly course (particle sizes ranging from 1/4 to 1 inch) and be relatively dust- and fiber-free. We were able to source Canadian-grown and processed hemp hurd from Plains Hemp in Manitoba.

Most UK-based hempcrete builders work with a natural hydraulic lime (NHL) as the basis for their binder. There is no North American source for NHL, so it tends to be expensive to import from Europe. We used an NHL 3.5 from St. Astier as one of our mix options. For a more locally-sourced version, we used a typical North American hydrated lime and a fired kaolin clay (called metakaolin) called Metapor. The NHL is a lime that chemically sets (hardens) through a reaction with the water content of the mix. North American hydrated lime does not set hydraulically (with water), but when mixed with a pozzolan like Metapor the two materials together have a hydraulic set.

The dry ingredients (hemp hurd and lime) are mixed together so that the powdered lime is covering all of the hemp, and then the water is introduced. Having done some work with hempcrete at Endeavour, we were surprised at how little water Tom uses in his mix. The final mix is just moist enough to lightly hold together when squeezed in a hand.

With some small scale mixes placed into test cones, we then moved on to installing hempcrete in some larger wall panels. These panels were built by Sarah Seitz for her PhD research work at Queen’s University, where she will perform tests to help determine the thermal insulation properties of hempcrete.

The panels simulate a typical double-stud construction, with a 2×4 frame on the “exterior” side of the panel and a 2×3 frame on the “interior” side.

As one group mixed batches of hempcrete in the mortar mixer, the others placed it into the forms and lightly tamped it into place. As the forms fill up, they are moved up the wall. The hempcrete retains its shape after less than 20 minutes in the forms. The filling and tamping continues right to the top of the wall. Once everybody was settled into their roles, it took less than 1.5 hours to fill a whole wall form.

In the end, we placed 40.25 cubic feet of hempcrete into the two walls. We used seven 40-lb bags of hemp hurd and seven bags of powdered ingredients to reach that quantity. With the small amount of water used in the mix, we’re anticipating a drying time for the 14-inch thick walls of about 2 weeks. This is much shorter than for the wetter mixes we have made in the past.

Cost-wise, we used $63 of hemp, $42 of hydrated lime and $21 of metakaolin, for a total material cost of $3.13 per cubic foot of insulation.

We will share Sarah’s thermal testing results when she has completed them. We are expecting to find their performance to be around R-2 to 2.5 per inch, meaning that our 14-inch wall would surpass current code requirements for thermal insulation.

This was a fun and informative workshop, and we’d like to thank Tom Woolley for sharing his deep knowledge of this subject with us!

Finishing the straw-cell wall system

Our office building project for the Trillium Lakelands Teachers’ Union features a straw bale wall system that combines conventional wood stud framing with an interior straw bale wall.

Recently, we finished the exterior side of this wall system. This involved placing dense-packed cellulose insulation in the frame wall, filling the cavity so the insulation is blown tightly against the straw bales. With the cavities insulated, we add approximately R-21.5 to the R-30 of the straw bales. Our contractor for the dense-packed cellulose was Morgan Fiene at New Energy Consulting in Hastings, Ontario (705-313-2004), whose care and concern for doing a thorough job was very refreshing.

We then covered the framing with an insulative wood fibre sheathing. This 1/2 inch wood fibre sheathing has an R-value of 4 per inch, and is made from 100% recycled wood fibre and a non-toxic binder. Made by Western Louisville Fiberboard in Quebec, this product is the cleanest sheathing product we could find. Most exterior wood fibre products use an asphalt emulsion coating, but the SONOclimat product uses a proprietary coating that is water based, non-offgassing and meets stringent environmental standards.

As a means to blend conventional wood framing with straw bale walls to achieve very high insulation values, we have been very pleased with the straw-cell system. It marries low impact materials throughout (earthen plaster, straw bales, cellulose insulation, FSC framing and recycled fibre board) with high insulation value and a straightforward construction process. It’s a great way to marry the more unconventional approaches to sustainable building with mainstream approaches.

 

Air tightness details for straw bale walls

Straw bale wall systems have been touted for 20+ years now as a way to achieve higher insulation values with lower environmental impacts. And, having built many straw bale homes and commercial buildings now, we know this is true. However, we have also seen that without attention to air sealing details, many straw bale buildings are quite leaky and fall short of their potential level of energy efficient performance because of this.

Along with many straw bale compadres world-wide, we’ve worked to come up with details that address these issues of air tightness in straw bale buildings. Our latest project for the Trillium Lakelands Elementary Teachers’ Local offices have good examples of easy ways in which a bale wall can be built to be air tight without reliance on whole-wall vapour barriers or other sheet membranes.

Plastered straw bale walls have a naturally air tight nature thanks to the continuous plaster coating. Any crack-free layer of plaster does an excellent job of stopping air movement through a wall. However, where plaster meets other materials (at the top and bottom of each wall, at each door and window opening and around through-wall vents and pipes), just plastering up to these seams does not create an air-tight barrier. All plaster types share the characteristic of shrinking as they dry or cure. Every edge of a plaster wall will pull away and leave a gap as the plaster shrinks. It may not seem like much, but even a 1/16 inch gap at the top of 100 feet of wall area is the equivalent of 75 square inches of “hole” in the wall! Add that same gap around every window and door and at the bottom of each wall and you may have a hole in your wall of up to 1.5 square feet! That’s like leaving an average sized window open full time!

Most homeowners understand that having a window open all winter long would have a negative affect on the amount of energy used to heat the home. But many people do not put the time and effort into “closing the window” around the perimeter of their straw bale walls.

For some, there is a reluctance to build air-tight because of a notion that it is unhealthy to seal a house “too tightly.” However, it is also unhealthy to be drawing outside air into your home through cracks and leaks in your walls. That infiltrating air picks up dust, spores, and anything else that is in the walls on its way into the house. Seal the house properly, and deal with the ventilation that is required in an intentional, clean way.

It’s not difficult to make an air tight bale wall. We will report on our blower door test results for this building as soon as we have performed the test!

Stop motion straw bale and earth plastering

Sustainable New Construction 2014 student Ben Bowman set up his camera and took some great sequences of the construction process at our teachers’ union office project.

Here are the two sequences of straw bale installation and earthen plastering. In many ways, these stop motion videos give a better sense of the process than an actual video, plus it makes it all look so fast and easy!

Ben also captured sequences of our earthbag foundation construction and roof craning process:

 

 

Plan Your Own Sustainable Home: A Workshop for Owner-Builders

November 15 & 16

Note: This workshop is being held in Toronto at The Living City Campus at The Kortright Centre, 9520 Pine Valley Drive, Woodbridge ON. All registrations must be through The Living City Campus.

Workshop Instructor:
Chris Magwood

Workshop Description

The dream of designing and building one’s own home is one of the most deeply held desires in our culture. The dream of designing and building a sustainable home marries that desire with a wish to live lightly (and affordably!) on the planet.

However, many questions face the prospective owner-builder setting out on this journey. To design yourself or hire a designer? To build yourself, or hire builders for different phases? How to choose from a myriad of competing natural building materials? How to choose heating options, water and waste options, electricity options? How to manage budgets and timelines? How to choose a piece of land? This workshop will explore all of these questions in an in-depth way.

The workshop is designed to be an un-biased look at all the options available to the prospective owner-builder, and to assist you with tools to help you assess and choose your way to the house of your dreams. You will leave this workshop ready to handle all the competing claims and information you will face by focusing on your personal goals and aspirations and creating a road map for how best to meet them.

Making Better Buildings book by Chris Magwood

Making Better Buildings by Chris Magwood

This course was the inspiration for Chris Magwood’s new book, Making Better Buildings. The book will be available at the workshop.

Entry Requirements
Open to all

Fee
$350
$630- Couple rate

Includes healthy lunch (vegan and vegetarian options available)

Maximum class size: 12

High-straw earthen plaster recipe

It’s no secret that we love clay plasters at Endeavour, and the best case scenario is being able to use a clay soil right from the building site. It just so happens that we lucked into this for the teachers’ union office project!

After digging some test holes on the site early in the spring, we discovered that there was a strata in the site soil that was quite clay-rich and appeared to have almost no stone in it (which is very rare in this part of the world). We made some plaster samples from this soil and found that a wide range of recipes seemed to be viable. We left the samples face up into the elements for the whole summer, and one in particular held up really well so we knew we had a workable site plaster.

Our approach to earthen plasters has changed over the years, with the addition of more and more chopped straw over the years so that we have reached a point where we have a very high-straw content in the plaster. We have found that the high-straw recipe allows us to build up the entire thickness of the plaster in a single application. The volume of chopped straw supplies a huge amount of tensile support for the clay, and means that we don’t need to add nearly as much sand as we used to do when our plasters used less chopped straw.

The result is a mix that is very sticky thanks to the high clay content, and has a huge amount of “inner cohesion” that allows it to be applied at almost any thickness (4-5 inches is not unreasonable, if necessary!) with no cracking.

Rather than applying a very runny slip coat via sprayer or dipping the bales, we’ve found that a layer of the same mix minus the straw works well as a “primer”. We apply the primer to the bales, and then follow it immediately with the high-straw “body coat.” It’s sort of a two-part, one-coat system. It’s great to be able to apply the full desired amount of plaster and achieve the final look we want in a single application. Less time, and much less concern for de-lamination between successive coats.

The mix stays moist for a day or two, so it allows a lot of time to get the walls looking how we want, and the mix is very intuitive for those just starting to learn to plaster, while being fast to apply for those with more experience.

Our recipe (by volume) for this plaster is:

  • One part high-clay content soil
  • One part chopped straw (1/4 – 1 inch)
  • 3/4 part rough sand

There’s nothing like playing in the mud and making a viable building at the same time!

New system for straw bale walls

Over 20 years of building with straw bales, I have constantly experimented with new ways to integrate bale walls into buildings that are simple, cost-effective and energy/resource efficient. From load bearing to prefab panels to a variety of framing systems, I thought I’d tried them all.

But we were introduced to a new idea by the excellent builders at New Frameworks Natural Building, and we liked the idea so much we decided to try it ourselves.

Their “StrawCell” approach involves building a conventional stud frame wall for the building which acts as the exterior frame and main load bearing element. One immediate advantage is that this system fits into the regular code structure and should not require special engineering or design considerations, which can really ease the permitting process and help to lower costs. The straw bale wall is then built to the inside of the frame wall, with the bales pressed against the framing. The stud wall cavities are then insulated with dense packed cellulose, and sheathed with a permeable board material. Any kind of siding/rainscreen can be created as the final finish on the exterior.

On the interior the bales are very easy to install. The only framing that interrupts the straw is for window and door openings – very similar to the easy installation for load-bearing designs. At the top of the wall there is no beam or framing to notch around, just a plywood plate on the underside of the roof. We tied each bale through to the framing, so the wall was very straight and solid right away.

While the amount of lumber used in this system was initially a red flag for me, an actual calculation showed that we were using no more lumber than any of the other bale wall systems that use a frame of some sort. A conventional frame wall is actually a very effective and efficient way to use lumber, and only some load bearing systems actually use less lumber than this frame wall approach.

One major difference between this system and other straw bale approaches is the lack of exterior plaster. This can be seen as both a plus or a minus. We have been shying away from exterior plaster finishes for clients, especially commercial clients like the teachers’ union. While we love plaster, it is both a high maintenance finish and one that is susceptible to moisture issues unless well detailed, well protected and well maintained. While we definitely have not sworn off using exterior plaster, we are certainly glad to use siding when the client and/or conditions make it appropriate. On the plus side, this system reduces the amount of plastering material and labour required by half (actually, more than half since the interior plastering is always easier). Interior plastering can happen at any time of year, while exterior requires the right weather conditions.

The addition of the cellulose in the exterior wall brings this wall system into the super-insulated category, capable of reaching PassiveHouse standards even in our cold climate (something a single, two-string bale wall cannot do). The cost of the cellulose and siding together are quite similar to the cost of the material and labour for exterior plastering.

All in all, we like this system so far. We’ll continue to report as we finish preparing the walls for plastering and complete the remainder of the system.

Craning a Finished Roof

Building a roof can be intimidating, and statistically the most dangerous element of making a building. The heights involved add risk, time and a lot of effort.

Whenever we have the opportunity, we build our roof structures – including all sheathing and as much finishing as possible – on the ground, and then use a crane to lift the roof and place it on the building. In this way, we reduce the risks associated with working at heights, lower the amount of physical labour involved in carrying materials to roof height and bring protection to our building faster.

For the teachers’ union office, we once again had enough room on the building site to do just this. We set up two rows of beams on the ground at the back of the property and fully erected the entire roof, including trusses, bracing, strapping, membrane, steel sheathing, light tubes and the full PV array. All of this was accomplished with the fascia less than two feet from the ground!

As we’ve found to be typical, the craning is a relatively quick process. We were slowed somewhat this year by wet conditions on site that made placing the crane in the right position difficult, but we still put all three sections of the roof on the building in a single day.

A quick look at the math makes a pretty good financial case for building roofs in this way. The cost of a day’s rental of a crane and operator is easily paid back by the efficiency and reduced labour time of building on the ground.

It’s not a carbon free practice, but when the site and conditions are appropriate – and particularly when working with student builders – it’s one place that we’re willing to let fossil fuels and mechanical advantage help us out!