First Plaster Layers

With the baling done by September, our goal was to get the first layer of plaster on the bales before the winter rains began.  Plastering has to be done while the weather is still suitable for quick drying, since it is not advisable to have wet clay against the straw for long enough to develop mould.  The faster it dries, the better.  Because it was September when we started, we decided to make this first layer no thicker than 1/2 inch.  If it had been June, we would have taken the seasonal opportunity to fill the dips, which would mean much thicker plaster in some areas.  However, we will probably go around in the spring and add plaster just to the places that are dippy, so the next layer will begin to smooth out the surface of the walls.

Once the baling was done, there commenced the job of stuffing.  This entails going over each wall and looking for spaces that push through the bales, generally where one bale meets up against another bale.  All along the tops of the bales needed stuffing, and sometimes where the framing separates the bales.  Tucking in tight little twists of straw to fill these places becomes methodical but doesn’t take too much time.

After that, comes the messy job of applying clay slip to all exposed straw.  We collected waste clay trimmings from a pottery studio, and soaked it in buckets so it becomes soft and scoopable.  Then we mixed it with more water to dilute it to a thick chocolate milk consistency, using a paddle mixer.  It was thick enough to not drip very much off a dip stick.  I created a little wearable square bucket to hold the slip while I slapped it on the bales with a big brush and a gloved hand.  The bucket, equipped with old belts that went over my shoulders, could catch any excessive dripping and free up both my hands to massage the slip onto the straw.  It dries a much lighter colour of pink.

Then came plastering!  We used local clay from an excavation job on the island, pitt run sand, (also from the island) and all that straw we collected from the bale trimming.  We built a soaker pit from damaged straw bales, lining it with tarps and then filling it with clay and water to make it soft.  On tarps, we mixed 4 or 5 shovels of the soaked clay with 10 shovels of sand by rolling the tarps around and then foot mixing, adding water as we went to get a good consistency without allowing the mix to be sloppy.  Adding a few handfuls of straw (equivalent to 2 or 3 shovels)  soaked up a bit of water, so sometimes we would add a bit more if it became too stiff.  The test is to make a ball, and not have it ooze or slop, but also not have it be too stiff and crumbly.  The other test often comes from actually applying it, and becoming used to the ideal consistency while working with it.  The hands on experience of plastering generally becomes the best way to really learn!  We had to adjust things as we went- our ratios changed as we dug into our clay pile and found less high quality clay.  We noticed that our mixes were more silty, difficult to apply, and orange in hue instead of blue/grey.  It was a subtle change as we filled the soaker pit, but after a few mixes we realized we needed to amend our clay from a different pile we had saved.  (After so many years of natural building, we have all sorts of little and big piles of resources hanging around!)

The clay slip gets sprayed with water before applying the plaster, just lightly, not so that water runs down the wall but the slip turns darker in colour.  A handful of plaster is then smeared onto the wall with the heel of the hand, and massaged in so that it doesn’t peel back off.  Everyone finds their own method, but the important thing is that it isn’t too thick, or too thin, ideally the same thickness, and it doesn’t peel off! Our first group of plasterers were my son’s school class, a group of 24 kids ages 10-14.  They spent a whole day rotating in groups between mixing, plastering, and hiking around our part of the island while birding and geo-caching.  They got so much done!  We also had a visitor staying with us for two weeks, learning all the steps of plastering.  For the next month, we had a variety of friends and community people coming by for a few hours or a day to get their hands muddy on our walls.

Partially dried wall

We focused first on the north walls, and the places where there is less sunlight and wind movement.  Then we moved to the inside when the weather got rainier in October.  Luckily, the fall was generally sunny late into November, so when we finally got to the south walls, the warm sun was still shining most days.  We used a fan to help dry out some of the inside walls that weren’t getting much sun.

plaster over clay slip with insulation at the top covered with metal lath

Plastering the bales in this build was different than the last house we did because the bales were oriented differently- instead of placed like bricks and plastering the sides of the bales we have stood the bales up and plastering the faces of the bales, where the strings are.  In the last build, we trimmed the entire bale walls, shaping the curves of the windows and removing any shaggy straw, so the plaster went onto the evenly cut ends of the straw.  This time, we couldn’t do any trimming because of the baling twine, and the plaster went onto the length of the straw.  While we didn’t need to take the extra step of trimming, it was a little more challenging to apply the plaster.  The walls are more lumpy and will need some extra work in the plastering to get a nice smooth wall.  Smooth walls, of course, are a matter of aesthetic preference over function.  Maybe in the end we will incorporate more creative sculptural elements into our walls.

first coat plastered dried. Burlap will be plastered into the next layer of plaster.

This winter will be a time for these seed ideas to take root while the house building projects are on hold.  We can take some time to sit in the house and imagine the different possibilities for the next phases.  It can be frustrating at times to have to be patient, but often the results come with better decisions and a renewed sense of creativity following the flurry of building.

If you read all this and want to see more photos and more descriptions of plastering, please refer to my previous post on the last house we did~ Natural Plaster

Building Straw Bales Walls

The last two weeks of August kept us busy as we were finally ready to place the straw bales into the walls of our house.  This was a completely different process from the first part of the house that we completed in 2013, in which we stacked the bales like bricks around a traditional timber frame.  This time we constructed a regular stud frame to support the roof, placing the stud’s on 16″ centers to accommodate the width of the bales in between the studs.  The stud wall effectively disappeared as the bales were placed between them and stacked up end to end to the ceiling.  At the base of the walls were toe-ups which the bales would sit on- filled with drain rock and rigid insulation (which also included some rough electrical).

The straw bales were reported to be 18″ wide, 36″ long and 14″ deep.  However, as we discovered when we got them, they were more like 19 or 20″ wide, which didn’t work too well with our framing.  So we set up two stations where the bales were cut before we could place them.  The first was an electric chain saw placed in an Alaskan mill device so the chain saw could slide easily across the edge of a bale at a set height.  Then the bale would get notched~ a second station in which a jig holding a grinder with a chain saw blade would carve a 4″ wide notch down the center of each side of the bale.

If we needed any specific length bales to fit into smaller spaces, which happened all along the tops of each wall, we would manually resize the bales first, then send them to station number one.  Eventually a system of tagging the bales with their length, as well as having a written order of the needed sizes on a piece of paper meant that when they were ready to go into the walls, we could just refer to the paper and the tags to put them in from one side to the other.  To make mini bales, baling needles, baling twine and a measuring tape are needed.  Thread the needles with twine, poke them through the bale at the needed length and in the same place as the original twine, pull one end of each through and then wrap the other end around the bale to tie them together… tightly!  Then cut the original twine.  Save those pieces for making other smaller bales.

An integral piece of equipment for getting the bales in was the CRAZY CARPET!!  It was quite difficult to shove the bales in, as we had to place the bale in against the open stud, place a crazy carpet against the straw of the bale on the other side, force the width through to the other side of the stud, then remove the crazy carpet.  Depending on the density of the bale, we had stakes to push with, mallets to slam with, and 2×4 scraps to persuade with.  Depending on the height, we could karate kick or shoulder check them as well.  The higher bales proved more difficult as we were working on ladders.  We had to be systematic in working right to left, (or left to right) along a wall as shoving a bale into a space with bales on both sides was pretty much impossible.  This meant that we had to be prepared with all the odd bales as we went~ we couldn’t just place all the easy ones first!  It also meant that things slowed a little sometimes while custom bales were made.

We inadvertently made a lot of cut straw byproduct.  The chain saw station produced 9 large garbage bags and two large mountains of 2 inch straw pieces.  The notching station made 5 large garbage bags of finely chopped straw.  We kept the piles separate, as the longer straw will be perfect for the first two coats of plaster, and the fine straw will be great for the final plaster.

The whole process called for continual creative problem solving.  The stud framing made for some very awkward spaces, especially around window bucks and in the corners.  We sized the window bucks to glass that we already have, otherwise we may have changed the sizes to fit evenly between the studs.  We ended up making a lot of 8″ or smaller bales and flipped them lengthwise in the spaces.  The corners also had a lot of these small bales stacked up, and we placed extra 2×4’s to hold them in place on the outside, and also to secure expanded metal lath around the outside corners so we could hand stuff those areas with loose straw.  We considered making forms and stuffing the corners with light clay, but the lateness of the season made us worried that the clay might not dry fast enough.  We will apply the clay plaster right over the metal lath, which is secured to the wall using zip ties attached to the baling twine of the bales in place.

The other awkward area is where the bale walls meet the main rafter on the south and north walls.  The rafter is made of two 2×10’s cut into a curve and joined together, and arches over the center of the bales, above the stud’s.  The bales come in underneath this rafter, leaving a 10″ space before the soffits and interior ceiling.  We cut strips of insulation and fit it on either side of the rafter, and used the metal lath to cover it and join in the with bales, so the plaster will extend up to the roof over the lath.

We ordered 350 straw bales from the Saanich Peninsula last August (2016) which is a mere 20km away.  Optimistically, we hoped we could get them in that fall- however, as our time line stretched into the winter, we resorted to storing them under a large tarp until the spring, when we moved them into the house in June after we completed the concrete slab floor.  There were many damaged bales, and after a huge sorting process of fully damaged, partially damaged, mildly damaged and good as gold, we ended up with about 250 in various piles.  We estimated that we might have needed to purchase up to 25 more, but in the end, we used every last one that was deemed good enough right to the last space.  Luckily, our enthusiastic gardening community purchased our damaged bales for their gardens.

So many of our friends came out and helped with the process during the two weeks that it took to get all the bales in.  It is always so humbling to have community members take time out of their own busy lives to volunteer for an afternoon or a day of slamming bales into our walls, or tying up smaller bales, or running the grinder or chainsaw.  The swimming pond became the ultimate spot for breaks, and many great conversations and smiles and eating of fresh fruit filled up the moments between hard work.  It truly made the daunting task of building our walls so incredibly enjoyable.  Thank you again to everyone who helped out!  We feel so supported and blessed.

Sub-layers of the Floor

Getting the sub-floor completed adds a whole new level of progress, allowing the next stages of the build to continue with greater ease.  The main floor of our straw bale addition went from an 18″ deep mucky clay hole to a finished concrete surface that we can directly lay the final tile floor on.  Here is an outline of the different layers and the process of putting them in.

1.First we filled the bottom with 6″ of gravel to cover the 4″ drain tile that runs under the house (as we are on a hillside with many springs weeping from the bedrock) and will allow any water that gets under the house to drain away easily.

2.Preliminary plumbing- all the plumbing is laid out across the floors and supported by the drain rock to create a slope across the main floor towards the septic.  The bathroom, utility room and kitchen water fixtures all come together into one 4″ main drain that exits to the east where it will end up in a septic tank/lift pump to take up to our existing septic field.

3.Insulation layer- placed directly onto the drain rock, we used whole bags of perlite that we laid out tightly side by side and gently flattened (by foot) to create a solid layer of 8″ insulation, which gives a R value of 25.  We chose to use perlite because it is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. (Rigid foam insulation is the usual building material for this use, but it is made of polystyrene.)  In some places we had to customize the bags by emptying them partially to help fill the spaces which were not the same shape as the bags.  Here is a link to the Perlite Institute which has complete information on using perlite for construction insulation below slabs – https://www.perlite.org/library-perlite-info/insulation-perlite/Perlite-underslab-insulation.pdf

4.On top of the perlite bags we put 2″ of sand, filling the spaces around the bags and then compacted the whole floor.

5.The next layer we put down on top of the sand was the 6mil construction poly vapor barrier and then laid out the metal rebar mesh that would be pulled up into the 4″ slab.

6.And the last thing we had to do before pouring the slab was attach the hydronic infloor heating Pex tubing to the metal mesh.  It is best to consult someone about the layout and spacing of your tubing as it will greatly affect the heating potential of your hydronic system.  It is also important to use sleeves to cover the Pex tubing where ever it comes up through the slab.

7.Once everything was ready we ordered the cement and Colin worked with a crew of 3 others to pour the slab in less than 3 hours.  The slab is flat, but not super finished as we will be putting 12″ mexican tiles down as the finish floor surface on the lower floor of the house.

The upstairs currently has a plywood subfloor.  We haven’t yet decided what we are going to use to finish it.

bathroom- exposed is the box with water lines for the bathtub, as well as venting and drain openings

 

GROUNDWORK- Building with Straw Bale

Last year we were approached about being interviewed for a short documentary about building with straw bales.  We are excited to share our story as well as our reasons for choosing straw bales and other natural materials to build with, and it is delightful to be among other home owners and builders who share the same sentiments about the homes we create.  We are currently on this journey once again, and the reminder of why we are doing this is truely valuable in the face of the various challenges that manifest during such a large and complex project.

Our wood working shop is also featured in Episode 1-Building with Cob.

Other episodes made are Episode 2- Building with Timber and Episode 4- Building with Rammed Earth.

*Made by TELUS Optik Local~ supports compelling, original stories told by filmmakers from BC and Alberta by providing production funding, training and exposure to new audiences.

Framing~ The Bones

roofDespite a very frigid December (for the west coast), we managed to continue building just in time to get the roof sealed up and water tight before the wet west coast winter starts in.  Here is a brief account of the structure of the frame, and the way in which we are going to insert the straw bales.

first wallOur decision to use a stick frame method as opposed to a timber frame (as we did for our first house) was mostly a compromise of time and money.  Stick framing is super fast, and we hired an experienced framer friend (thanks Danny!) to work with Colin and his design with the curved roof lines.  Dan helped Colin put his drawings into a model of the house in Sketch-Up, a computer program for architecture, so they could get accurate measurements for all the framing, especially where the lengths of the 2×4’s change subtly with the curves.  The curved roof was the main reason to use stick framing- it was eaiser and faster to frame the studs under the curved beam which is essentially two 2×8’s (cut out of 2×10’s to get the curve) overlapping all along as one continuous header the length of the roof- this also alleviates the need for headers over doors and windows.  Framing started on December 2, and was done in a month, despite a week break over Christmas.  We still have some interior shear walls to frame, as we were focused on the walls that were necessary for the roof.  Also, window and door framing will be cut in sometime in the spring.  Many people have asked us about how 2×4’s can be the only thing holding up a living roof, but the engineer says they are strong enough with the 3×8 beam on top.

The exterior walls are framed to 18 inch centres, as we will be standing the bales on end between the 2×4’s.  A lengthwise notch will be cut down each side of the bales to fit them snug around the framing, and thus hide the wood frame down the centre of the wall of bales.  The new international building code for straw bales has published findings that the bales placed 14 inches wide in the wall is the same insulation value as their 18 inch wide option, due mostly to the orientation of the straw.

All of our interior walls are shear walls (plywood on one side, and attached to the foundation directly), as required by the engineer, since our exterior walls are straw bales and not considered to have any shear strength.  The shear strength is the load that an object is able to withstand in a direction parallel to the face of the material, as opposed to perpendicular to the surface.  In walls, it is usually plywood or cross bracing that provides the shear strength, preventing any side to side movement.  So our internal walls are (or will be) sheeted with plywood and continue down to the foundation.  At the foundation, the walls are secured with hold downs to resist any upwards movement in an earthquake.

The roof is standard construction with 2×4 strapping over 2×12 joists, though in the more curvy parts of the roof we had to use double layers of 1×4.  On top of the strapping is standard 1/2″ plywood decking and a 4″ curb all around the edge to keep the dirt in.  We decided to go with a double layer torch on roof membrane this time, which should easily last a very long time, longer than us… The roof was torched on in early January and we are now secure and dry for the rest of the winter.  Colin is back to work in his shop for the next few months to get caught up with his ThujaWoodArt projects, but come the spring we hope to do the infloor heating and plumbing under the concrete slab on grade subfloor, and prepare for installing the straw bales in the summer.  We will be offering workshops for installing the straw bales and plastering in the summer through the local Heartwood Folk School, check their website for more info as we get closer!

Phase 2- Continuing the Build

foundationFoundationThe basis on which something stands or is supported; a base.  The basis or groundwork of anything.  An underlying basis or principle for something.

An overview–  The previous straw bale house chronicled on this blog was the first section of two parts of our whole building plan.  The first half is designed as an in-law suite for my mother, with a shared art studio space, and this second half that we are just starting will be bedrooms for us and our kids and a garden level living space.  The 3 acres that we have contains a lower open feild where the pond and gardens are situated, a forested upper area, and a sloping face of bedrock in between.  Since we don’t want to clear the forest or use up valuable growing space, we have designed the house to be built on the rock.  The first half sits at the top and overlooks the pond and gardens, and the other half is separeated into two floors, each built like a terrace from the garden level up to the existing section and attached with an enclosed walk way.  The total square footage will be about 2,000 square feet.

excavatorWe are building with as much attention to natural materials as possible.  We are using sustainably sourced or salvaged resources whenever we can.  The walls in this half will be straw bale with clay and lime plasters, with a living roof, just as in the first half.  We are aware of the imprint of building houses these days and the huge amount of toxic off gasing that occurs with many conventional materials as well as the chemically saturated waste that ends up in the landfill.  However, since we are building within the boundaries of building codes and needing to meet the requirements of engineers, architects and inspectors, there are just some things we can’t avoid.  Natural building can be a tag that is placed on our house as a whole, but I think it is important to state that not every aspect of the house is “natural”.  Such as, for example, the foundation.

The second half-  There are not many places in Canada where you could begin to build a house in November.  Of course, we didn’t plan to start at this point, but the process of aquiring the permit took longer than we expected.  We learned from our previous build that everything will take longer than expected.  Amazingly, the weather has been quite co-operative, allowing us to complete the form work in one week, and giving us the sunniest day of the month on the day we scheduled the pumper truck.

There is not much about the foundation that would fall into the “natural” category.  We hired an excavator to dig the footprint, and rented a large rock drill with a giant, gas powered compressor to drill out 140 holes in the bedrock, each ranging from 16″ to 24″ deep and filled with concrete grout and rebar.  We purchased a lot of 2×10 and 2×4 lumber as well as some plywood for the forms that we hope to re-use again in the framing if possible.  We set five runs of rebar inside the length of the footings and stem walls with a 1′ grid of rebar in the higher walls and snap ties every 2 feet, and placed knockouts of pvc in the footings wherever we need drainage, septic, and water runs.  We hired a concrete pumper truck and 3 truck loads of concrete.  We set anchor bolts every 3 feet in the top of the concrete to attach the framing.  The engineer is happy, the geo-tech is happy, the building inspector is happy.  This is not terribly extraordinary in the world of regular construction, in fact it is quite standard and even a “small” job.  To me it seems rather complex, requiring a lot of effort and money to create forms that become deconstucted and a structure that is largely unseen in the end.

However, this crucial first step is the foundation upon which we will begin to build up our visions of a beautiful, healthy, comfortable, sustainably functioning and lovingly hand built family house.   

 

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.

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