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.

Straw Bale House Building Work Party

NATURAL BUILDING WORK PARTY!  Learning opportunities for straw baling, light clay, and plastering starting now and continuing throughout September for our straw bale addition on Pender Island, BC.

It has been a rather unpredictable summer in terms of our building schedule, but we are finally at the point of putting the straw bales into the walls of our house.  These things just always take longer, right??  We started off on Monday, August 21 with an enthusiastic group, gathering in the morning to check out the partial solar eclipse that was visible from this part of the continent, and then spending the rest of the day getting the order of operations sorted out.

Our method of placing the bales standing up in the columns created by the stud frame is different from what we did for the other half of the house, which was a timber frame structure with the straw bales stacked like bricks and secured with exterior vertical bamboo.

We would like to invite everyone who is interested in experiencing building with straw bales to come for a few hours, or a few days, to take part in a variety of jobs which will shift over the next few weeks as the work progresses.  From this point onwards, there will be many tasks to complete, and while it will be difficult to schedule the type of work being done over this next time period, we would like to offer a general list of natural building components that we will be looking for help with:

  • trimming, notching, sizing, and stacking bales
  • stuffing
  • light clay- we will be filling some areas
  • clay slipping all the wall surfaces
  • mixing and applying the first coat of plaster

light clay- filling the forms

Give us a shout and let us know when you can come and we will try our best to let you know what we will be doing.  Or, let us know what you want to do, and we will contact you when that job will be happening as soon as we know.  Things will be much quicker depending on the amount of help we have, but realistically, we also have to consider the cooling of the days as we get into the plastering part of things.  The plaster needs to dry completely within a certain time frame… same for the light clay.

trimming and notching bales

This week, August 23 – 25, and August 27-31, we will be working to fill the walls and we are looking for extra help.  Anyone that is interested in learning a different way of building with straw bale is welcome!    We also have a lovely pond for swimming and will be providing snacks.  If you are from off island, please send us a note of your interest and we can provide more details.

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!

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