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

Light Clay

The framing of the house created some interesting areas that were challenging to fill using straw bales, so we decided to do a little light clay instead.  In the upper level, the framing of the roof joins in with the framing of the floor, leaving a narrow wall space that widens out with the curve of the roofline, so filling this oddly shaped wall space with light clay was a great solution.

Light clay is a mixture of loose straw coated with clay slip and packed into a form.  The form is removed right away to allow for quick drying time, and there you go… a nice flat straw surface solidly held in place by the clay.

The process is fairly simple.  We spread loose straw on an old piece of plywood, mixed up some clay and water into a nice thick slip, poured it over the straw, and tossed it with a pitch fork.  We were looking for an end result of long straw that would stick together when squeezed, with no clay dripping or running off, but with the colour of the straw no longer golden.  Like a salad dressing… lightly coated.

 

We did the first foot of wall, adding screws or nails into the framing to give a little something for the straw to tuck into, and packing it in securely but not densely.  After we took the forms off, we let it dry out for a week, then did the rest of the wall up to the window bucks.  Our wall section widens out once it gets above the roof framing, but we didn’t want to fill the whole space at once and risk the centre staying moist for too long.  We put the forms back on higher up and did our second lift in another few hours.

This was the first time I had done any light clay, and I know it is another whole natural building method in it’s own right.  We have helped some friends build their house with chip slip, which is the same as light clay but uses wood chips instead.  The mixing of clay and straw has been used as an infill material for timber framed buildings from at least the 12th century in Germany and elsewhere in Europe.

It was really great to so easily utilize a variation of natural building in our predominantly straw bale house.  I think we would have done more in some of the other awkward spaces, but the timing of the summer sun was a bit late for ensuring a complete drying out of the clay slip, and we ended up making lots of small oddly shaped bales to stuff with.  But that will be another post~ the results of baling above this light clay wall and then plastering over the whole thing was quite positive.  The flatness made for a lovely plastering experience, compared to the lumpyness of the bales… but that will be another post as well!  Stay tuned as I catch up on a busy summer and fall of building.

The Earthen Floor

burnishing the floor at the "leathery" stage

The south room floor is the one spot in the house where we continued with our plan for laying out an earthen floor, in hopes of capturing the heat of the southern sun that streams in during the winter months.  The rest of the house, which was originally intended to be an earthen floor, became cork flooring due to some time pressures and uncertainties regarding the success of the earthen floor process. (See my previous post titled The Layers Beneath Our Feet for a total description of the floor.)  We found lots of information, tips, recipes, ideas, things that didn’t work, and things that did from a variety of resources, some of which contradicted each other, or were from climates very different from ours, or which used materials that were unavailable or too expensive for us.

lots of considerations and discussions

Figuring out what to do was challenging.  Tracy joined us again for the experience of mixing and laying our earthen floor, and we are grateful to her for sharing her observations and experiences of working with natural plasters.  (Tracy is our natural plaster and straw bale teacher.)  We wanted to use what we had and we felt most comfortable with techniques that were familiar to us from the wall plastering that we had just completed.  Cracking seemed to be the biggest common result, and one that is difficult to fix without a very messy look.  We heard of filling the cracks with different coloured plaster to create a marbled look, but we never found a source of a good example of this method.  A certain amount of experimentation, intuition, applied knowledge and trust was going to be needed.  This was the point at which we were grateful that it was now only a small 200 square feet that we had to do.

clay slip

We decided to follow (loosely) a set of well laid out steps and recipe ideas from Anne and Gord Bailey, of Eco-Sense on Vancouver Island, ecosenseliving.wordpress.com.  We adapted the recipe to what we had available, which was screened clay mixed into a slurry, red clay mixed into a slurry, stucco sand, horse manure, straw, and some red pigment.  We started by laying down a cob sub floor at a depth of 3/4 inch using a mix that resembled our second coat of wall plaster.  When that was dry we mixed up the top layer in 5 gallon buckets, then tried a technique we saw on the internet of laying burlap all over the floor area, wetting it and slopping clay slip as a binder then troweling on the 1/4 inch thick top layer.  I am breezing through the details here because it didn’t work.  We thought that the burlap would help reduce the shrinkage factor of the clay that leads to cracking, but it didn’t at all, and it also prevented the top layer from bonding well to the layer below the burlap.  We think it dried too fast, the layer was not wet enough, the burlap wasn’t soaked well enough, or there was just too much clay content in the mix to begin with.

troweling on the top layer

So we ripped it up!  Just chipped through to the burlap and pulled, and it lifted too easily.  We crumbled it back into the buckets, then worked out a few new ratios of higher sand and straw contents.  We laid out some sample areas and let them dry to see how the cracking went, and decided to make the mix with 4 parts sand, and one part clay slip.  Because of the remixing, it is hard to say what the quantities were for the various other ingredients.

sifted manure

Fibers (manure and straw) were around 1 1/2 parts, and water content was based entirely on feel and how the mixer spun.  Not too wet, not too runny.

This time we left out the burlap.  We also poured buckets of water all over the floor the night before to keep the cob subfloor cool and to prevent it from sucking moisture out of the layer we troweled on top.  We hung blankets over the windows to try to keep the summer sun from hitting it right away.  It took a whole day of two people troweling on hands and knees to get our 200 square feet covered once again, then while it slowly dried we lay planks across the floor so we could burnish it, giving it a polished look while compressing it more, and hoping to prevent too many cracks.  The outcome was 90% better than the first try.  We had a few thin cracks, mostly where it dried the fastest, and no lifting.

The recommended method for fixing the cracks was to use some left over plaster.

the worst of the cracking after the second try

We dried it out, crushed it, screened it through window screen, then sprinkled it into the cracks while wetting the area with a mister and troweling it smooth as best as we could.  There was a bit of texture difference for sure, but we decided that it was a natural floor overall and a bit of texture was fine!  Then we began with the oiling and waxing.  This was another reason we were glad to have done only a small portion of our floor- we brushed on 3 coats of boiled linseed oil, and two coats of Land Ark oil, which contains beeswax, tong oil, linseed oil, citrus extract, and pine rosin.  Land Ark is made with only natural, non-altered ingredients from sustainable resources, without chemical processing, bleaching, or harmful additives.

oiling with linseed oil

We have also used it on the timber frame,door and window trims, the baseboards, and the ceiling boards.  It actually feels great to get on my skin, and I love the smell of it as I have done much of the staining.  For more info on a great product- www.landarkwoodfinish.com.  The cost of this oil runs at about $85 a gallon, so we were hesitant about what it may have cost in oil to finish a larger area of floor, since we didn’t know how many coats the floor would take.  We read that it could be anywhere between 3 and 10, with at least 2 being the straight linseed oil.  Then we waxed the floor, using another natural wax from Land Ark, and then buffing it hard with a buffer.  The golden flecks of straw suddenly jumped out, and the places of various texture and colour deepened and settled in.

The best part of the finishing of the floor was not anything that we read or heard about in all of our earthen floor research, and so here I would like to add it in as a recommended part of laying an earthen floor.  Don’t move in any furniture, but set up the stereo.  Lite some candles, build an altar, and invite as many people as can dance on your floor.  Put on a rocking playlist, strip off the socks and stomp, swirl, boogie, laugh, and send all that energy of celebration, gratitude, and joy through the soles of your feet  into the hard work and beauty of the earth.  That’s what we did, quite unexpectedly.  We felt warmly supported by our friends, and happy to finally be able to open our space for gathering together and sharing what we have.

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