Solar Panels, electrical wiring and hemp walling in the rain

The indoor work site

Sunday it rained heavily on and off throughout the day but this did not stop work continuing on the house under cover of the roof. The electric pan mixer was set up in one of the back bedrooms, beside it I had a barrel of water to dip my bucket into for water. The barrel could be kept always topped up by leaving the hose dripping into it. The wall mix was about a bucket and a half of water, 5.5kg of hemp, one 9kg bag of binder and 8.5kg of river sand.

The mix ingredients showing the difference between volume and weight

 I started with half a bucket of water in the mixer. I measured the hemp out from the bulk bags into three identical buckets, filling each to about where the ridges of the rim began. I added the weight of one bucket together with one third of 5.5kg of hemp and so measured out each bucket to a total weight of 2.74kg on my, newly purchased from e-bay, electronic hanging scales. The scales were set up under cover of the eaves in one of the sliding door openings next to where the hemp was stacked. I added two buckets of hemp then the rest of the bucket of water, the third bucket of hemp, the binder and the other half a bucket of water. I kept a bucket under the outlet to catch any water leaked and added this back to the mix. The amount of water and consistency was done by eye rather than strict measurement - the aim was a damp muesli. At the end the sand went in. When the mixer got really full after the sand sent in, it sometimes pushed the mix around the mixer rather mixing it. When this happened I just let a bit of the mix out into a bucket, the rest of the mix started mixing properly again and the part in the bucket was added back into the mixer again.

Large flexible buckets were useful to discharge the mix into, a bit at a time. A full load filled about 4 flexible buckets three quarters full. The flexible buckets have two handles and were light and easy to pick up and were able to be shaped as needed to pour the hemp mix into the formwork. A scoop made from a cut down juice bottle was very handy to get the hemp into small spots or to direct it into a specific spot. A range of timber and tampers was used to tamp the mix once poured and levelled in the formwork in layers of about 5cm. Short lengths of timber were useful to tamp in hard to get to spots. When I got up to under the first noggins the formwork, by luck rather than design, was higher on one side than the other and I was able to push the hemp in under the noggins by hand. This was easier because the noggins were right at the top of the formwork. And so I made the next rise on top of the two small sections of wall I had made previously. Working on my own was slow work. I think team of four, two preparing and mixing and two tamping, would be an efficient workforce.

Hemp wall second lift

7am Monday it rained again, but not long after Paul and the boys from Solar Connections arrived the sun came out and the solar panels went on the roof , despite the roof still being a bit wet. I had originally planned the put the panels on the back pavilion, but following discussions with Paul I changed this as some tall trees to the east meant that the back pavilion did not get sun until late morning. The main pavilion faces true north, but the roof slopes 12 degrees away from north, so the panels were put on a tilt up stand to get a better angle for solar collection. The eight panels make up a 1.5kw system.

Solar Connections installing the solar panels on the roof

The change to the location of the solar panels means that they are now visible from the back pavilion, particularly the west bedroom, but fortuitously they fall behind the wall between the highlight window and sliding doors and do not block and can not be seen from the highlight window. I am worried that they will block a bit of the sun coming through the glass door into the bedroom, but hopefully this loss will be made up for the higher amount of electricity they will generate in the sunnier location. I had thought that the panels could start working as soon as I got the meter changed over and start generating electricity for me. Unfortunately the inverter (that turns the DC current from the panels into AC that can be used for appliances and fed to the grid) needs to be mounted on an external wall, and as yet we have a frame but no wall, so I will have to wait until the final electricals are done to start generating solar power.

Solar panels hidden behind the wall between the highlight window and sliding door

Monday I also had another delivery, the 78 bags of hemp lime render for the inside and outside of the house. The pallet of render arrived in a large van rather than a truck and without a lifter on the back I wondered how they would unload the pallet. As the driver explained - by hand. The driver backed the van up to the end of the drive and started unloading, he was incredibly fast, practise from unloading beer kegs he explained. I had only taken a few bags into the house by the time he was finished. I then had the job of packing the bags from the end of the drive into the house. After doing five pallets two weeks earlier, one pallet was no worries. Just a few spots of rain and a quick cover of the load with a tarp got me hurrying along.

Paul and the boys from Solar Connections also did all the electrics. For the light switches and power points in the external hemp walls they ran the cabling in conduit to plastic boxes. Following discussions with Paul we worked out the easiest way to do them was to set the outer edge of the box 55mm from the frame, the same spacing my formwork will be. This way the formwork can be screwed on and the wall filled without either having to cut a hole in the formwork for the box or providing some sort of filler so the box did not fill up with hemp. The 55mm distance was used by placing a 10mm packer of timber behind each box. When we render the walls we will just have to remember to put some sort of packer on the box so that the render will not curve off at the boxes and will have a flush surface when the face plate of the switches is attached.

Plastic box for power point

Cables run in conduit to box

While the electricians worked away. I put duckboards around the outside of the back pavilion to keep us out of the wet and sticky mud as we make the walls and to give a hard surface to work on. I also made a ramp into the house so we could easily move the mixer in and out. After this I started working on the formwork for the first rise of wall around the back pavilion, so next time we are on site we can get started making a long length of wall.

Form work and duckboards

Plumbing first fix and second hemp wall

My plumber Len made a great comment about the house "I like the design, but not for the plumber." The house had two bathrooms at opposite ends of the house and the kitchen is not near the bathrooms either. The town water connects to the house at the the opposite end to the water tank, and the toilets and washing machine are all connected to rainwater from the water tank. The water and LP gas pipes all run between the ceiling and roof and then down the walls, where possible they will run down the internal walls which are not hemp, but there are not many internal walls in the house.

The water pipes are all PEX (cross linked polyethylene), but where sharp bends are needed, such as going out  through the wall to the water tank, the pipes are copper. Len, my plumber, also lagged all the pipes that are going through the hemp walls. When I asked why he used the thick black lagging around the pipes, his reply was that he had it sitting around in his garage for a while, it being the type of lagging used on solar hot water systems, but when he ran out of the black he will use a thinner green lagging, like used for hot water pipes, for the rest of the pipes that go through the hemp walls.

Lagged pipes running through what will be a hemp wall

Pipes coming out through hemp wall to and from water tank

Gas (yellow) and hot and cold water pipes running to kitchen

While on site I also did a second test hemp wall. On further inspection the first test wall I did was slightly bowed out in the centre on one side. I am not sure if this was caused by the formwork being bowed or from over tamping. So for the second wall I checked the formwork was straight using a level as a straight edge and checked the wall as I put the hemp in to make sure the tamping did not bow the formwork. After the lesson of the first wall I also made sure that I tamped the corners and other areas around the spacers. The result was a better wall on my second test section. I continued to put up formwork and as a further precaution against bowing in the centre I put an extra spacer and coach screw in the centre of each sheet of formwork and to prevent creating difficult areas to tamp I put the spacers and screws further in from the corners.   

Two test sections of hemp wall done and formwork moved up

This section of wall was made with one mix

I have also made peace with the surveyors after they did not carry out the house set out survey properly. They refunded me the extra cost I had to pay for the extra concrete piers and have offered to do a final survey at no cost. This final survey is likely to be necessary to prove to council that the house is still with in the required set backs, even though it is not in the location specified on the Council approved plans.

First hemp wall

Finally I have started building my hemp masonry walls, but it almost did not happen. I had arranged for the ingredients for my hemp walls to all be delivered on Friday - Hemp, Binder and Sand (I already had the fourth ingredient, water, on site).

Shoalhaven river sand

About 7.30am Friday 5 tonnes of river sand arrived on a truck from Ison Home Hardware in South Nowra. The truck could only go on the driveway as the ground was very soft and wet from the rain, so it was left on a tarp and some builders plastic to one side of the driveway. River sand in the Shoalhaven area comes out of the Shoalhaven River and is unusually a dark grey colour. It was explained to me that this was from ash in the river from many bushfires.

Not sure when the other deliveries would arrive, I started working on the formwork. The area I chose to start on was a small section between a sliding door and a control joint. The control joint is required above where I have a control joint in the concrete slab. Control joints were put in the slab at two weak points to prevent cracking by allowing any movement to take place in the flexible joint filler. This then needs to be followed up vertically in the walls above the joint in the slab. Like the slab I will cast the walls in two sections, using the left over joint filler from the slab in between. This small section had lots of studs, a door jamb and a corner in it making the formwork quite fiddly. In the very tight section we used boards only 45cm high as it looked like it would be difficult to tamp if the formwork was any higher. I used 55mm spacers cut from old conduit with 100mm hex head coach screws. I drilled a hole in the board for the screw then used an impact driver to put the screw into the studs.

Corner formwork

 By lunchtime, no further deliveries had arrived and no phone calls either. Then I got the call from a Shoalhaven delivery company, that that had left four messages for me, but had been phoning me on the wrong number, so I obviously did not get these messages. They checked their invoice on which was my correct phone number. I was then told that the truck had gone out for the day, could they deliver on Monday. I explained that I would not be on site on Monday and I had arranged for helpers to be on site to help with the deliveries. They told me they would see what they could do.

In the meantime I phoned up to see where my hemp delivery was. I was assured that the delivery had been booked in, but at 2pm my hemp was still in the Hunter Valley. It appears that the transport company was having some difficulties. A few more phone calls throughout the afternoon and delivery was arranged for 7am Saturday. Sue from Ecofibre phoned me at 5.10pm to confirm that the transport company had picked up the hemp.

The afternoon was not wasted as I had also organised the Council inspection for the frame as I needed this done before I started covering it up with the hemp walling. The inspector arrived on time, looked at all the work, and the only changes I had to make were to add in two sections of diagonal metal strap bracing that had been specified by the engineer but not put on and to put a second nail in each piece of metal strap bracing where it crossed each stud. This was all dome and fixed before the binder arrived.

The truck carrying the binder worked past their usual 3pm knock off time to deliver my binder on Friday and it arrived at after 4pm. We had hoped that the truck could back up to the house and unload the pallets of binder onto the slab, unfortunately as the truck turned to reverse toward the house one of its front wheels came off the concrete driveway and almost got bogged in the soft ground beside the driveway. The truck only just managed to get out, leaving behind a trail of dirt and a big hole beside the driveway. The truck was not able to go off the concrete driveway, so the closest it could get was the end of the driveway. We had to move 5 tonnes of binder by hand.

Lucky escape for the truck

5 tonnes of binder waiting to be moved

The binder was in handy 9kg bags, making it easy to carry two at a time - a necessity when there were 520 bags to move! The midwinter light was fading as we moved the first pallet. A bright halogen builders light allowed us to work on in the dark. We finished moving all the binder into the house at 8.30pm just as a few spots of rain fell. Moving the binder only took 2 hours for two people, but work was interrupted by the need to bath and feed out three year old.  

I chose to use the Australian Hemp Masonry Company binder, as it comes premixed (easier when you are building a whole house), is made in Australia and has been well tested. We got the smaller 9kg bags of binder as we are using a 120 litre pan mixer, rather than a 300 litre mixer that can use 18kg bags. Klara from the Australian Hemp Masonry Company has also provided me with support getting Council approval and with building questions I have had.

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Bag of binder

One pallet moved, four to go

The hemp from Ecofibre in the Hunter Valley arrived in a semi trailer at 7am on Saturday morning and it took up the whole floor of the semi with three more bulker bags stacked on top of each other. Matt the semi driver tried to back down the driveway, but the road was too narrow to turn in without damaging the lawn of the man across the road (who came out to make sure his lawn stayed in good condition) and some low electrical lines also made it tricky. So the bales needed to be unloaded from the roadside. We had originally thought we could roll the 110kg bags into the house, but after the first one was rolled off the truck we quickly discovered that this was not easy as the loosely packed bales did not roll well, flattening out on whichever side was on the ground. The bales were also too heavy and bulky for my partner and I to lift.

Matt the driver spotted a forklift working at the hardware store about 200m down the road, so I went down and asked if we could hire the forklift and driver for a short while. Unfortunately the forklift was not able to go off the premises, but JP at Culburra Beach Home Hardware did loan me his pallet jack, which turned out to be our saviour. Matt rolled each bale off the truck and it landed on one side on the pallet jack, we then took each bale up to the end of the concrete driveway. We could not leave the bales at the front of the driveway as we share it with the people who own the house in front of us. Once we go the the end of the driveway or where the bales had filled up to we just lowered the pallet jack and pulled the bales back upright and off the jack. The driveway was damp and very muddy from the truck that nearly got bogged the day before and the bales filled the whole of our section of the driveway.

The hemp truck unloads

Bale moving part one completed

While we were taking a short break after moving the bales onto the driveway, I received a call from Tony, a friend I had met doing the two hemp building workshops. He was stopping by to have a look at the house and was quickly roped into helping move the bale into the house. An extra person made it much easier to move the bales. As the ground between the driveway and the house was wet and muddy we made a temporary road out of OSB boards and a ramp up into the main pavilion of the house. The pallet jack could now be used as it needed a flat hard surface to work on. Each bale was tipped over onto its side onto the pallet jack, with two people pushing and one pulling the pallet jack we got up some speed, enough to make it up the ramp into the house without too much strain. With some careful stacking all 27 of the bales were brought into the house, in what became quite a smooth system of moving them. I am extraordinarily grateful to JP from Culburra Beach Home Hardware for the loan of the pallet jack and to Tony for helping move the bales and for having the great suggestion of leaving a small pathway between the bales at the end of the hall so we could at least walk through some of the house. The doorway from the main to the front pavilion is completely blocked with hemp bales.

Temporary road and ramp

Bales all safely moved into the house

By mid afternoon we had two sections of formwork up and made our first mix. For each 9kg bag of binder we had to weigh out 5.5kg of hemp. The hemp was incredibly light and we soon discovered that our scales, which only measured to the nearest 100g, were insufficiently accurate (hanging scales accurate to 10g have now been ordered through e-bay). The hemp has a pleasant barn-like agricultural smell to it and was easy to get from the bales into buckets.

The Aardwolf pan mixer was beautifully quiet when we tested it empty. The question was whether it would be as quiet with a full load - it was.  We added water, hemp, a bit more water, binder, then once it was well mixed, 8.5kg of sand. We added the water a bit at a time, until the mix looked and felt right, but will work of getting a more accurate water measure, bearing in mind that the amount of water will vary with the conditions. We wore gloves, dust masks and eye protection. With the binder in small bags it was easy to lift over the mixer and pour in slowly and this kept the dust down.

We got the mix out into flexible buckets, that could be shaped into a spout like shape to pour the hemp into the formwork, although in the narrower sections we put the hemp in by hand, which was quite inefficient. We will try and manufacture a scoop from a plastic milk container like they did at the Billen Cliffs house. The smaller tamper we had made worked well getting around the studs, even this was not small enough for some sections and we resorted to using using pieces of timber on end. Tamping down into the step down in the concrete and around the damp proof course was difficult and where a narrower tamper will be useful. The location of some of the spacers also made it difficult to tamp. The work was not heavy and we did two mixes making a wall about 45cm high.

The hemp looks like playground mulch

Test wall section

Mid Sunday morning we removed the formwork. From the top the wall looked very fibrous and like it might fall apart as soon as I took the formwork off, but when the formwork was removed, and it came off easily, the wall was surprisingly solid and straight. When the hemp is put in, in small layers of about 5cm deep and tamped evenly you can not see a line between one layer and the next. When we looked carefully at the wall there were a few spots where you could see a difference between each layer. The real problem was in the bottom corner where a spacer too close to the corner meant that the hemp was not tamped into the corner and just fell out. We will fix this when we fill in the holes left by the spacers.

Test hemp wall

Spacer too close to edge to tamp

A beautiful hemp wall

There is room for improvement, but the wall was not bad for a first go. We will do another test section before moving into full scale wall building. We are looking for volunteers to help build the hemp walls over August, September and October 2012, for more information e-mail culburrahemphouse@hotmail.com  

The roof is on

The roof is on - well most of it. The roof is being done in two stages. The main roofs are done and the awning roofs and where they intersect with the main roof will be done later. This is to allow for the hemp walls to be built behind the awnings. Watching the roof go on with all the flashings have thrown up a number of problems such as  - How we are going to build and detail the finish of the walls where the roof abuts a vertical hemp wall? - Can you put lime render over Colourbond flashing and if so how do we get it to stay and not crack?  - How will be build the funny bit between the hall roof and the main pavilion roof above it? These are questions I will have to do further research into and try to answer.

Monday morning work starts on roofing the back pavilion

 Strangely the roofers arrived Monday morning and only worked until 10.30am before going to finish another job. I wish someone had told me about this earlier. My plans were rearranged to stay on site the following day when the roofers returned. The roof is Colorbond Custom Orb (corrugated) in shale grey colour. It is hard to get a sense of the colour of the roof as in direct sunlight it looks almost white and in shade as dark as a mid grey, and various shades in between. The Custom Orb sheets are laid over a combined sarking and insulation called Kingspan Aircell Insulbreak. The house will also have further bulk roof insulation added between the rafters, just before the ceiling lining goes on.

Work continues on the main pavilion roof

Shale Grey in sun and shade

Tuesday morning was cold and my son and I took up a spot in the sun to watch the roofers continue with their work. By morning tea the main pavilion roof was on and by lunch all the roofing was on and they started on the barge capping and over flashings. A foamy strip precut to match the corrugated profile was installed under the top barge capping to prevent water or debris blowing up under the top of the roof due to the low pitch of the roof.

All roofing on and commencing the barge capping

The light played funny tricks with the colours of the roof and barge capping

With the roof on I could see the pattern of sunlight through the windows, although the scaffolding in the way created extra shadows. It was beautiful to see how the winter sun will stream through the windows, particularly the highlight windows above the north facing sliding doors.

The different shades of the fascia and barge capping can barely be seen in the bright sunlight

 

Midwinter sunlight streams into the back pavilion

The roof can hardly be seen