Category — Construction Diary
Hempcrete and Bricklaying Begin
July 6 – July 10
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Hempcrete can only be found in a handful of buildings but it’s only a matter of time before this insulation technique spreads. Hempcrete is a mixture of lime, water and hemp shives (core of the stem) packed into the wall cavities boarded with plywood forms that leap frog upward, similarly to the slip straw walls we have already completed, as you finish a layer. Also like the slip straw, this will take at least a few weeks to dry before it can be plastered. We were hoping that the mixer that was bought for the course would be ideal for mixing the hempcrete but it wasn’t to be. The mix we were looking for was heavy on the hemp so that the curing time is as quick as possible without compromising the structural integrity or insulating qualities of the finished product. This meant that we could only mix in about half the hemp we wanted in the mixer or else a big gooey mess resulted. After adding in the second half of the hemp into the first couple of batches by hand, a member of the crew known for his staggering genius suggested using the tiller we had on site to break up the hard clay used in the slip and plaster to incorporate the remaining hemp into the mix. Thankfully it worked very well, much to the delight of all that had toiled away mixing the first two batches by hand.
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Something we neglected to add to the journal in the weeks leading up the break was all the hard work happening on green roof. There was plenty to do laying the waterproofing membrane, border lip, and layers of growing medium. In fact, one morning saw the entire course commandeered into a makeshift bucket brigade to send all that gravel and sand up to the roof via some scaffolding and many pairs of hands. We have a great professional working with us, who also happens to be an alumni of the course, to get this done right. It will be very exciting to see the native plant species that will be planted up there hopefully thriving next season.
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One other big job that began this first week back from our reading week was laying the brick wall that separates the foyer from the main hall section of the building. Using reclaimed brick from the area, a few lucky students along with Kevin Dunfield of Dunfield Masonry, began putting together what will be a focal point of the interior. The wall contains two arched openings and so far looks like it will be spectacular. In addition to this brick section, the interior walls team also added the wooden framing that will enclose the office and mechanical room, and the metal studs that will divide the two bathrooms and food preparation/arts and crafts area.
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As the time begins to melt away quickly, it was also nice to see some painting going on as well as much preparation for the shingles to start to be installed next week. Things are really coming together nicely on site and as always we encourage everyone to stop by and check our progress on Tuesdays between 5:30 and 6:30.
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July 12, 2009 2 Comments
Animal Tracks and Slip-Straw
June 22-26
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Slip-straw is another good use for straw, an abundant byproduct in Ontario. It is the combination of clay and straw to insulate wall cavities. The straw is hand-tossed with slip, which is watered clay, then packed into the walls that have temporary forms up. Not all the seeds are removed from the straw before it gets bailed so seeds start sprouting from the walls days later. What’s really cool is that we won’t need a moisture tester to tell us when the slip-straw is dry inside because the sprouts will tell us when they die. Once that happens, in at least 3 weeks, it’s time for lime plaster.
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The earthen plaster application was also in full swing. We had to make sure the inner walls were finished in order for the floor to be poured so that was the first job tackled. The bales are not exactly a uniform surface so the plaster had to be applied in different depths in different places. Starting at the bottom of the walls the plaster is applied quite liberally to support the plaster to be applied above it and to make up for the inconsistencies in the bales. The toughest areas are around the door and window opening and along the top plates. Wire mesh helps the plaster but also resulted in a few nicks and cuts to the plasterers if they weren’t careful. The bales had been beveled around the windows and doors as well to allow for nice smooth rounded corners there. The goal was to get the walls as straight and level as possible so that the eventual finishing coat, which will be applied after this thicker and more fibrous coat has dried, can be thinly and quickly added.
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The floor team met with Keith Dietrich to put together a plan for the floor pour which will be concrete with 50% of the portland cement replaced with slag, which is a byproduct of the steel industry. Animal and bird foot print stamps were hand carved and used to make tracks in the floor before it finished setting. A semi-circle around the entrance and a 6 foot diametre circle in the centre of the main hall were left untouched to be tiled in later. Radiating out from those are imprints of plant and tree samples picked from around the building. Printing was the fun part but it was incredible just how fast, precise and difficult it is to pour a concrete floor properly before it sets. For two days, Keith led the crew through the thin to thick all day trick with their wheel barrows, rakes, floats and trowels while he screeted and made it really shine. We used stamp mats to make the entrance foyer look like bedrock and a brown hardening pigment to make the office a beautiful chocolate brown. It looks really great already and the detail to be added should set the look off even further.
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Elsewhere on site the soffit and fascia team was still hard at work and a few dedicated souls even managed to get a little reeding in. Thanks to good planning, the crew have the following week off so the floor and walls could have a week undisturbed to set and cure.
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July 12, 2009 No Comments
Time to Bale
Week of June 15-19
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Once the north wall was ready for straw bales, Chris and Jenn gave us a workshop to get us ready to bale and plaster. The students learnt such valuable information as how to know a good bale when you see one, how to test if it’s dry enough, and how to tell clay from silt. Then the experts demonstrated how to size, dip, install and tinker with the first few to get us going.
 Pushing the bales down a bit helps the clay plaster to soak right in.MVG |
Off we went, laughing, getting muddy and making something great together. In only a few days the builders had the whole north wall filled to the roof with straw bales and ready to plaster. The easiest part is getting the bales stacked and in place, but making sure that they are as straight as possible and that the gaps between the bales are tightly filled with “baguettes,” or loose straw bundles with both ends dipped in slip just like the bales, can be the tricky bit. We use big wooden mallets or “persuaders” to pound bales or entire wall sections into submission.
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Another team was busy readying the earthen plaster for application on the finished bale walls. As mentioned above, the bales were pre-dipped in clay slip for a better adhesion with the plaster which is made of local clay, sand and chopped straw made from left over bales. The windows and door openings as well as the top plate, were covered with wire mesh to give the plaster a better surface than just finished lumber to adhere to and in those spots the plaster doesn’t have any straw fibre added. Earth plastering is so much fun and generally safe to work with, including skin contact and accidental ingestion. You can’t say that about many finishes in our building world today.
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In the mean time, other builders were busy elsewhere installing electrical wiring, boxes and sockets that will support the lighting and other electrical needs in the building, and covering the radiant tubing with sand and gravel in preparation for the pouring of the concrete floor. It almost seemed like a shame to cover up all that hard work but the efficiency of the heating system will be reward enough and we have high hopes for the design of the finished concrete floor. The team has put a lot of thought and effort into the design and it will be nice to see it come to fruition next week.
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Speaking of design, the week was also a spent making some final aesthetic and finish samples and decisions. The sketches look both impressive and ambitious so hopefully we can pull it off and deliver a building that is not only sustainable but also pleasing to the eye as well!
July 12, 2009 No Comments
Floors Ready for Radiant Action
June 8 – June 12
 Radiant floor will be heated with geothermal refrigerant that will transmit the heat from refrigerant to water. The heated water will travel about 300 feet before looping back the cooled off liquid.MVG |
Now that the roof is on, the biggest project to attack was the floor. The floor team had the space inside our perimeter beam foundation filled to a point where it was ready to be insulated in preparation for our radiant tubes to be installed. First we laid down house wrap over the entire surface to make sure we avoided punctures to our vapour barrier that followed the typar immediately. After that came the 2″ silver board insulation that will prevent heat provided from the radiant tubes from being lost to the ground. It involved lots of cuts to make it all fit around existing plumbing, electrical and interior walls as well as lots of tuck taping a different metallic bubble wrap insulation over all of the seams. The team also ingeniously made some gaskets for around the plumbing pipes to ensure there is minimal thermal bridging. All the intricate work will go a long way to make sure the building is a super efficient envelope.
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Once the insulation was down, it was the radiant floor teams turn to get the tubes laid that will be the primary mechanical means of heating and cooling in the building. They will be the mode of delivery for the output of our geothermal system when all is said and done. The tubing has to be laid in a certain way to make sure there are no significant cold or hot spots on the floor which means many separate and shorter loops in a specific configuration. If you just did one large circuit, the water enclosed in the pipes would only really effect a small area of the floor before it returned to it’s starting temperature. Below you can see all of the different loops outgoing and return locations. Eventually a header will be installed over all of them that will allow the user to adjust the temperature by controlling how much water is actually flowing into each loop.
 The “swtichboard”. Valves placed on the hots side will allow occupants to control what part of the floor they want heated. If occupants are not using one part of the space, they can turn it off.MVG |
Some other things going on around site were a few finishing touches on the metal roof such as the ridge cap which contains a vent to allow for ventalaion. The soffit team was hard at work installing in the high peak on the south side of the building. This is a slow process as the cuts are really precise and scaffolding had to be erected to facilitate the installation. Tongue and groove cedar was chosen as the material and let me be the first to tell you that it looks fantastic.
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Away from the roof, the earthen plaster team was busy getting their slip pit up and running which will be necessary for the on site straw bale wall building next week. Each bale is dipped in the clay slip to allow for adhesion between the bales and the plaster that will cover them when completed. It is a dirty job but as you can see below, an enjoyable one.
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The other big job for the week was mixing all of the lime plaster that will be used on the interior and exterior walls. The lime is mixed with water and left to soak in barrels until we are ready to use it. A bit of extra water is added to ensure that the lime accepts as much as it needs to be an optimal consistency for application. Another very messy job, not to mention hard on the arms due to the amount that we will actually use on the building.
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June 17, 2009 No Comments
