Bales of Insulation- A Full Report

exterior bamboo piningWe are heading into our third season of winter in our straw bale house.  Hard to believe really – I so clearly remember the feeling that the house would just never be done – but there you have it, two years later we are really beginning to see the way the design and materials of the house perform through the seasons.  Last winter was a relatively mild winter in an already mild climate zone, and the winter before we didn’t really move in fully until January, so getting a sense of how much wood we might burn and how much our heating/electrical costs would be throughout the winter months has only just begun to be obvious.

winter sun bouncing off the pond

winter sun bouncing off the pond

Our three forms of heat are the wood stove, hydronic in-floor heating, and passive solar orientation.  The winter sun arches across the sky, sending it’s light and heat into our east and south windows (when it is out!) staying entirely above the top of the trees of the ridge across the valley of which we face.  At certain times of the spring and fall, the light of the sun bounces off the pond below us which lights up our ceiling with ripply light- an unplanned bonus!  We have an earthen floor in the front room, which noticeably absorbs the warmth and retains it into the evening.  The wood stove sits on a two foot tall stone hearth and is backed by a short cob wall, both of which absorb sun heat as well as stove heat.

In floor heating tubes covered by 3 inches of cob sub floor

In floor heating tubes covered by 3 inches of cob sub floor mass

Our in-floor heating is divided into two zones, one for the bathroom and north side of the house, and one which circulates the front south room.  They are set to come on if the temperatures of the rooms drop below 19 degrees celsius.  The front room heating has never come on, and the backroom zone clicks on early in the mornings of the coldest days of winter.  The tubes are embedded under 3 inches of cob, which then also retains heat for longer.

We primarily rely on the wood stove for immediate heat.  This year we lit our first fire on November 20th, and mostly because we were nostalgic for that first cozy fire.  We kept the fire going for about an hour, and then we were too hot.  We have found that we really only need to light a fire around four or five o’clock, depending on the temperature outside, and let it die down around nine, otherwise it gets up to 25 degrees!  upraised wood stoveWe have been having a cold spell right now, where temperatures fall towards -2 or -3 degrees at night (oh my!), and then we might light a fire at three in the afternoon.  Our evening fires keep the house sitting at 20 until late the next day.  Last year, this translated into our using less than half a cord of fire wood in the whole season.  We have an older style stove that doesn’t have any of the newer reburning/efficient innovations, and our space is 920 interior square feet.

The southerly exposed room of the house is lowered by two steps, (which is where the wood stove is) and so the heat tends to naturally move towards the north side of the house as it attempts to travel upwards.  If we leave one window open in the loft of the back room, the heat is pulled even more into that space.  Another design feature of the walls themselves are the wrap- around construction – meaning that the bales are continuously wrapped around the outside of the timber frame, leaving no thermal breaks except where there are doors and windows.  We used double pane thermal glass with argon gas and a low-E squared coating.

west side, south side

south and west side- wrapping bales, sun exposure, and roof overhang

I love the heat that a wood stove gives, but I am not excited about the amount of wood and trees that need to be burned.  It is not entirely a “clean” way of heating.  Eventually we will have three wood stoves on our property – this one, one in the work shop, and one in our addition to this house.  Luckily, Colin’s business of crafting furniture from salvaged red cedar means that we have a lot of  great kindling and fire wood just from his waste.  I am comforted to know that we can potentially heat our spaces for years on just a few dead or cleared trees.  We took out a few trees when building the house, and haven’t even started using them.  This fall, I chopped almost two cords of wood from those trees, which will potentially be three years of wood.  The less wood we go through the better – we even find that turning on the stove to make dinner warms the space efficiently some nights.  Certainly, if we have friends over in the evening, lighting a fire usually leads to opening some windows.

Straw bales reportedly  have an R value of 30-60.  The building code requires that insulation needs to have an R value of 20 in walls.  We have experienced this amazingly efficient quality of insulation, in the winter and in the summer, when the inside of the house is cool and refreshing on hot days.  With a 3 foot overhang of the roof blocking out the sun’s light in summer and the rain in the winter, I am ever more convinced that straw bales are a fantastic way of providing natural temperature control in any climate.

Eco-Homes Tour and Symposium

A comment that we hear regularly from those visiting our strawbale house is that not everyone who wants to have a naturally built house is capable of doing it themselves.  Indeed, it takes a lot of hard work, research, material searching, building skills, tools, and time to go through the process as a home builder of any type of project.  Anyone without such prerequisites but with a desire and willingness to learn certainly can go for it, but there are many out there for whom it is more realistic to hire someone else to build them a home.  This is prevalent within the conventional building industry, but where does one look to find a straw bale crew?  A natural plaster expert to source materials and use their knowledge of crafting healthy walls?  What about an architect who will consider the natural light and water conditions of your chosen spot?  All of these job positions are readily available for the standard house, but difficult to find for alternatives.

On Pender Island, a group of people wanting to promote various aspects of natural building have formed the Eco-Homes Network, in hopes of being able to provide services and information for anyone seeking to build a healthy home, as well as networking with other builders in the community to create a greater awareness of alternative materials and systems.  Education for clients as well as builders is a large step towards integrating healthier building practices into any house or project, whether it is classified as “eco-friendly” or not.  Why limit ourselves with labels and categories?  Any system that takes pressure off the resources of the earth and saves money in the long term is just a good idea to consider.  The Eco-Homes Network consists of Rob Zuk – a solar systems consultant, Ken Rempel – an architectural designer, Garrett McLeod – a traditional timber framer and carpenter, Colin Hamilton – artistic woodworker and natural builder, Tracy Calvert – an extensive natural builder and master of earthen plastering, and Jude Farmer -  a woodworker and man of many skills.  In fact, everyone in the group has many crossover skills and knowledge spanning many years of different experiences within the building industry, including roofing, tiling, stonework, workshop leadership, landscaping, flooring, and planning.

For two years, the Eco-Homes Network has set up a demonstration zone at the Pender Fall Fair and has hosted an eco-homes tour as part of an effort to educate people about natural building practices, and to showcase the many beautiful homes around us that incorporate different aspects of the industry.  At the Fall Fair, everyone has been invited to squish their toes in cob and plaster mixes, and try their hands at spreading the mix over a demonstration wall of bales in a timber frame.  There also has been many books to gaze through, knowledgeable people to talk to, and a photo board of projects to look over.  Many people get a good sense of the simplicity, creativity, and beauty that encompasses the building of a natural house.  The Eco-Homes tour, which takes place a week later on Labour Day, is a self directed tour of up to 10 houses around the island, and has showcased houses made with chip-slip walls, strawbale, cob, cordwood and Faswall blocks (compressed recycled wood chip blocks), and including features such as earthen floors, living roofs, natural plaster, rain water catchment systems, hydronic in-floor heating, solar hot water, passive solar, composting toilets, and countless other details and creative touches that make up a complete picture of a natural house.  Some of the houses have been in the construction phase, allowing visitors to see the layers of some of the processes.  There have been over 150 people from the locals to travellers from the mainland and Vancouver Island each year, asking many questions and hopefully taking some ideas back to their own homes.  All proceeds from the previous tours have gone to the Pender Community Hall and to the Pender Island Farmland Acquisition Project.  This year, proceeds will help the growing Pender Community Transition movement, to build a more sustainable island.

The Eco-Homes Network is adding a new element to the tour this year.  On Sunday, September 4th, The Building Around Water Symposium will be a day  focusing on water systems and living roofs as well as a mini tour featuring houses with such systems for viewing.  The six houses on the tour will be open for visitors in the morning, then symposium events will be commencing at the community hall in the afternoon.  All the homes are located along Port Washington road, within a few kilometers of the hall, and would make a beautiful morning walk, jog, bike ride, or car stop!  Lunch will be available for purchase at the hall at noon, with speakers beginning at one o’clock.  Water on the gulf islands, as well as in many other climates world wide, is a concern needing immediate addressing and rethinking in terms of efficient usage and collection systems.  Droughts and shortages have become more widespread as our climates shift, reminding us of the valuable place that water holds in our lives.  Adam Scheuer, president of Water Tiger Rainwater Harvesting, will give a talk and answer questions regarding rainwater collection systems.  Living roofs are a great way to incorporate water catchment, as well as maximize water absorption and minimize water evaporation while providing more habitat for birds and bees.  Living roofs are gaining lots of attention as features of large commercial scale developments, but they are also beneficial for residential homes, and so there will be a presentation on the installing and maintenance of green roof systems.  In our marine climate zone, there is much concern around the use of vapour barriers.  Many alternative wall systems, such as strawbale, cob or chip slip, provide a breathable wall which does not require a vapour barrier but does now require an envelope engineer such as Ben Martin, who will talk about designing and building with thermal mass wall assemblies, vapour barriers and codes.  Starting at 6:30, there will be a show and tell slideshow by our local builders demonstrating their own creative, recycled, sustainable, and artistic projects.  Anyone wishing to add their 5 minute, 10 photo presentation to the line-up can contact Colin Hamilton at 250-629-6608.  This part of the day will be free to all.  The rest of the days’ events are $20 per adult, children under 18 are free.  The Eco-Homes Network has a new website to help promote the vision of building healthy homes.   www.ecohomesnetwork.com

The Truth Window

A traditional feature of strawbale houses is the truth window – an opening through which one can see the straw inside the walls.  Like every strawbale house, truth windows are unique and creative, providing a little peek into the golden stems.  Truth windows often take on the role of an altar, bringing gratitude for the sources of our materials and reminding us of the reasons for the choices we have made.  We have seen truth windows as elaborate wood frames, recycled metal grates, little doors that open to reveal the straw, and anything in between.  We went through a few different designs before we finally settled on the simple use of the clay plaster as a sculpting medium in which to frame and hold in place the piece of glass against the bales.  I decided to build out the bottom of the frame to create a small ledge in which to place little treasures, much like the objects that adorn an altar.

First we trimmed out a recessed area of the bales by about 4 inches and set the glass in place.  I used a pair of chopsticks to help hold up the plaster that would shape the top curves of the frame, then applied a first coat of plaster.  With the second coat of plaster, I built up the shape that I wanted in the curves, and added the little reveals above and below the frame.  The beautiful thing about such a sculptural style of building is that you can really make it up as you go, erasing and starting over, correcting and being surprised by what happens.  I haven’t done much sculptural work in my past, so getting the picture of what was in my head on to the wall was an interesting challenge of dexterity and a good lesson in flexibility.  What the truth window ultimately ended up being was a combination of a vague idea and surprise.

For the finish plaster,  I used the coloured plaster that Tracy and I had made up for our colour samples for the front room.  We ended up with a beautiful orange that was too dark for the whole room, but would make the truth window stand out against a lighter shade of the same colour.  We haven’t done the rest of the room yet, but we are working on getting all the other prep details done so we can do the final plaster sometime in July.  So for right now, our finished truth window sits lovely and peaceful amongst the strew of construction and chaos.  We look forwards to sitting just below it, eating our meals and rotating our treasures in gratitude for the soil, the sun, the rain, the seeds and the hands that cared for what has become the walls of our home.      

Have Bales, Build Walls

Colin and I explored and learned about many alternative building materials, but strawbale construction was not one of them.  The closest we came to seeing them in use on the west coast was as a north wall in a hybrid house with a southern cob wall.  It made sense- cob being a poor insulator but with beefy, heat sink mass wall, and bales being great for insulation in places that receive little sun.  Strawbales have been reported to have an R value (insulation measurement) of anywhere between 30 and 60 (with code minimum being 25 here).  We also learned that such decisions should ultimately be made when the land is chosen and the building site has been  observed for weather patterns, with an open mind free from any construction type bias.  We first considered strawbales when we began asking around to people in our community, and found a few existing strawbale houses, and one friend in particular who has built with many different types of alternative materials.  Tracy soon became our walking resource.  (Yes, the same Tracy I mentioned in the natural plastering post.)

Our building site is perched on the top of a bedrock slope facing due south, but with a longer east/west side, so while we have full sun all year, we also need lots of insulation to capture the rays with as much passive solar practices as possible.  The rectangular shape of the space available between the outcrops of rock made the use of bales easy to apply.  The bales provide infill walls only, as we designed the timber frame structure to hold the weight of the roof, which extends out with a 2 and a half foot overhang on all sides to keep our rainy climate away from the walls.  All the strawbales came from Mitchell’s, a family owned farm on the Saanich Peninsula.  They had an excess of barley bales that year, and as we inquired about 700 bales needed for our house as well as for a workshop that our friends were building at the same time, they were happy to help with a reduced cost and extra arms loading them into the moving truck that we rented to move them over to the island.  We used the structure of our roof and timber frame as a place to stack all the bales together while we worked on a few things that needed to be in place before the bales went into the walls.

We constructed the toe-ups for the bales- a step of sorts that the bales sit on.  This is a path of 2×4 lumber on it’s side, bolted into the foundation, and filled with drain rock.  We heard of people using crushed glass (from recycling depot), or corks (lots of trips to the recycling depot!) or anything that provides fill with air gaps.  We also used these toe-ups as a course for our electrical wiring, running the wires inside the lumber then up to our electrical outlets that were posted at the required height up from the 2×4, and being essentially free standing from the bales.  We protected the wires from the drain rock with a small piece of rigid foam insulation.  We did this for a few reasons, the main reason being that the electrical inspector wanted to see the rough wiring before the bales potentially hid them from view, and we didn’t want to get partway through our wall stacking then have to wait for him to make his visit, which can be the case if wires are run between bales.  We also wanted to run the wires up the backs of the timber frame to the places that would need wiring up high.  We stapled strips of burlap all along the places where the bales would come up next to wood, and a strip of building paper on the outside of the burlap.  This was more for the plastering stage, but it was essential to do it before the bales went into place.   We then posted bamboo poles on one side of the toe-ups up to the height of the top beam.  This was to be a part of our exterior pining system.  After the bales were in, we placed bamboo poles on the other side then sewed them together with a giant needle and baling twine through the bales, inside to outside.  We also put in place all the window bucks, securing them to the timber frame and the toe-ups so that they would not shift with any settling of the bales.  This created more detailing of the bales around the framing, but we had heard stories of frames shifting out of square and plaster cracking, so we decided to go with the rigid framing to avoid potential problems.

Finally we started building the walls, and with lots of eager hands!  Many of our friends had asked to come and take part, so we invited anyone who wanted to help.  We had a rotation of 4 or 5 people everyday for the week that it took to fill in the walls.  Although it was now november, we had a beautifully dry and sunny week to work in.  We learned how to reshape the bales to fit smaller spaces, either with a small electric chainsaw, or by splitting them and retying them with that giant needle.  We used zip-ties to tie the bales together end to end through the baling twine, and the fact that the twine on the bales was so tight it was hard to slip a zip-tie under them was a good sign that these tightly baled bales would be good insulation and might not settle too much.

We were even able to incorporate the enthusiastic pleas of our little ones, giving them lots of jobs with the small bales we created for the small spaces, and with the continual cleanup of loose straw everywhere.  They mostly settled into playing on the constantly diminishing pile of bales, but it was with great satisfaction that I could say that our building materials double as a healthy play fort.  I was also grateful for our decision when I spotted flocks of chickadees foraging through the litter for seeds and nest building material.  I loved finding the occasional sprig of dried wild chamomile bundled up into our walls, adding an element of calm to the energy of the house.

The last job was trimming.    Colin used a grinder and gave every inch, inside and out, a careful haircut to get a smoother surface on which to plaster.  Then we did a bunch of stuffing- making little twists of straw and shoving them into any little cracks that are created between the bales or around the window framing.

I am really grateful for the process we went through that arrived at the decision to build with strawbales for this house.  It has been a satisfying experience all along, from the many people that walked in and smiled with memories of family barns in their childhoods, or the soft cushiony sound of the acoustics as we played music perched on bales as benches, or knowing that any excess will go onto my garden paths or as summer mulch.  It is a building material that fits beautifully into the harmony of natural world, and creates those wide, adoring window sills that frame such glorious views of the world we honour and respect. 

Natural Plaster

A large part of the strawbale construction of our house is the natural plaster system that closes in the bales while still allowing a flow of air to pass through, supporting a breathable wall system that is totally weather proof.  I am not going to pretend that I can write a whole how-to guide here on this post, but instead I hope to give a most complete account of what we did to our walls, and hope that it is helpful to anyone interested in taking on natural plastering, or it is interesting to anyone just curious.  There are many books, websites, people of knowledge, and workshops out there that can give accurate (and sometimes conflicting)  information, and we have taken these steps available to us for what makes sense for our situation.

We have been blessed to have with us in our community an experienced natural builder and good friend, Tracy Calvert.  She has been integral in directing our experience, and helping out with the attaining of supplies and tools.  She is especially experienced in the art of natural plaster and it’s many layers of applications.  Our first layer was covering the straw bales with  clay slip, which is essentially like splattering the straw with thick chocolate milk.  Messy.  We obtained the clay from a pottery studio on Mayne Island, it is the off cut pieces from the creations of the studio which were destined to be sent to the landfill.  Some studios take the effort to reconstitute these wastes back into usable clay, but it is an arduous task to reproduce good quality clay.  Many studios prefer to consider these bits unusable, and so having them picked up by natural plasterers is a positive move for everyone.  After soaking the clay, we mixed it up with a heavy duty paint mixer mounted on a drill, until it was thick and smooth.  My method for getting it on the walls was to splash it on with one hand, holding a bucket below to capture what didn’t stick while rubbing it into the fibre of the straw.  Whatever technique is used to get the slip on the wall is a good one, there really isn’t any wrong way.  I covered every visible straw bit of the house, inside and out, turning it a lovely shade of dark reddish-pink.  It then spent a whole winter like this.

Layer number two is a cob mixture of clay, sand and straw mixed up in batches by foot and pushed on the walls by hand.  We got local clay from a farm down the road who was excavating a pond, pit-run sand from a local quarry, and the shavings of straw from when we trimmed the bales to make the surface even.  A good test for determining the quality of the clay is to do a jar test- put some clay in a jar with water and shake it up, then let it settle.  This will show the ratio of silt to clay, and whether or not there may be too much silt in the clay.  Ideally, the less silt, the better.  We built a soaker pit from leftover bales draped with a solid tarp, and kept it filled with softened clay ready for using.  After spraying the walls to get the slip wet, we pushed on the layer of plaster, spreading it about a half inch thick.  We started in early spring with a birthday party for our 4 year old, inviting all his friends and their families- really, this layer isn’t very difficult to master and it’s lots of fun to do with friends.  I had home school plaster parties, ladies’ night plaster parties, and afternoons with a few friends and their kids playing nearby.  The inside and out was finally done by the fall.

I was able to get started on the third layer in April.  Tracy came for a morning and went over the variation of the cob mix- this time the ratio of clay to sand was 1:2, with one and a half buckets of finely sifted straw.  (I used a certain bucket for measuring, and went through a few mixes of experimenting with ratios before finally getting to the mix that cracked the least.)  The sand we used was a finer, washed sand.  This layer is applied with a trowel, and encompasses the task of sealing in the flaps of burlap that connect the bale walls to the timber frame.  (Since clay doesn’t stick to wood very well and shrinks when it dries, a strip of burlap was stapled to the backs of the places where straw meets wood, and so the clay doesn’t move away from the wood when it dries.)  The burlap has to be rightly stuck down, so we brushed it with more clay slip until it was nicely saturated, then we rubbed it in roughly with plaster before applying a smoothly troweled layer of plaster.  We also took the time in this layer to shape those beautiful big curves of our windows, sometimes building up the flares with extra plaster until the shape of the curve was formed to our liking.  This is also the layer into which any sculptural work can be done, which we all know is the best part of natural plaster and cob. Nana enjoyed contributing her artistic sculptural skills around the house.

I was much more careful about who I invited to help with this layer- I mostly took it on myself (although Taeven and Cedar both took on their own ways of plastering with the trowel so they could help out).  I had the help of a few friends who are artists (good hand-eye co-ordination) and who helped with the previous layer, so they had an idea of what the result was to be and they came many times to help, building up their experience of working with the plaster.  My own abilities changed so much with this layer as I worked around the house, that I have re-plastered much of the first area I started on, seeing flat spots on window curves and too much cracking in other places.

We also covered some of our interior walls with plaster.  In the mud room, we built a stud frame wall, then stapled expanded metal lath to the sides, filling in the middle with straw.  The plaster goes straight on the metal, in two layers to avoid any movement of the mesh beneath.  The final layer of plaster is yet to be applied, and will undoubtedly require a whole new lesson in natural plaster.  The outside will be a mix of lime, sand, and colour pigment, the inside coat uses finely powdered cayolin clay as its base.  We fine-tune the quality of our trowels with Japanese trowels.  There is more technique involved in applying the plaster to avoid lines showing up…  I am looking forwards to working with Tracy again to learn this new skill level of natural plastering.  The journey of using natural plaster on our walls has been long and enjoyable, I have massaged every inch of our house with friends, conversation, children, family, quiet musings, music, meditation, in the sun and the rain.  I have mixed every patch of plaster with the energy of my feet and legs, and with the soles of friends.

Our Strawbale Home

My husband, Colin, and I spent a few years previous to when we bought our land, checking out a variety of natural building projects- cob, stawbale, rammed earth, cordwood, houses, garden sheds, playhouses- in various states of construction, doing workshops and reading books about land development theories and off-grid possibilities.  I remember walking into peoples’ homes, finished or not, and wondering when I would be the one answering questions in clay dusted work clothes, passing on the vision of a beautiful and healthy living space.  A few weeks ago we hosted our house on the Pender Island Eco-Homes tour, and I was able to see myself in just that light as I greeted over a hundred people throughout the day.  It’s been 2 and a half years since we began the foundation, and 2 and a half years of living in a 23 foot trailer as a family of four in the mean time.  We have worked beside a huge array of friends and community neighbors of all ages, with many of our materials being locally sourced.

Buying into the land with us (and making the reality of the price affordable for us all!) is my mother Margaret, otherwise known as Nana.  Colin and I have always welcomed the idea of shared land buying and building- we researched and looked into the prospect of larger, intentional community style projects here on Pender before this piece of land presented itself in such a way that we could not ignore.  We asked around for anyone else who wanted to join in, but it seems to have worked out for us to get going with Nana and keep our doors open for future co-creators.  The whole design of the house involves two more small levels descending down the rock slope in front of the part we are currently building, which will be a level of bedrooms and a level with an open kitchen and living room for our growing family.  The section we started with is a 590 square foot suite for Nana with a 290 square foot shared art studio.  This strawbale house opens into a nice size mud room, with a door leading south to Nana’s kitchen, bedroom, and living room space all in an open format (the front section with the curved, living roof).  A door leading north from the mudroom goes into the art studio and utility room (back section of house with sloping metal roof).  There is a small storage loft above the mudroom that will serve as a bedroom for the kids while we are building the other half of the house in the future.  We chose to build the house in sections due to the fact that we are living in a 23 foot trailer, and Nana is paying rent down the street, and getting one section done faster so that we can move into it together is much more appealing than waiting even longer and stretching our finances further before getting something comfortable to live in.  Nana has been a great help with taking time with Taeven and Cedar, baking us bread and treats, making meals when we are working late, and adding her artistic touches when she can, as well as taking on any jobs she can help with.  She also manages to help plant, weed, or harvest in the garden.

Colin designed the floor plan himself with considerations of the passive solar capacities available through the south facing slope that we are building on.  He hired our friend Garrett (McLoed Timber Framing) to design and work with Colin on the traditional wood jointed frame.  We used beams salvaged from old bridge timbers by a company on Vancouver Island.  The bales were bought from a family owned farm in Saanich, and we are covering them with natural plaster- a foot mixed combination of clay, sand and straw which is then spread over the bales by hand, and then covered with another layer smoothed by a trowel.  A final coat of lime plaster will seal in the  whole wall system, keeping it breathable, dry and super insulating (Straw bales are reported to have an R value between 35 and 60!)  We have a hydronic in-floor heating system laid beneath an earthen floor, the final layer being yet to happen.  This past summer we had a fabulous work party to get all the soil up onto our living roof, and it is now planted with native succulents and other sedums that I have been propagating over the last 2 years.  I hope to be able to post our continuing developments as we work this winter, as well as describing in more detail of any of the steps we have already completed.

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