Sunday 26 August 2012

Hemp Walls Second Rise

Leaving behind a big storm in Sydney we spent the weekend in spring like weather at Culburra building more hemp walls. Friday we finished the first rise of the back bedroom and started the second rise up to under the noggins in the other bedroom. The form work was only moved up half a rise to just under the noggins so that we could tamp the hemp under the noggins. This was done by working in the usual method, including using a "L shaped tamper" to get under the noggins, up to about 5 to 10cm under the noggin when one side was built up and tamped before the other and we used our hands to push thee hemp  mix under the noggin . Once under the noggin was filled the other side could be filled and tamped in the usual way.

First rise finished
Hemping done up to noggins, outer form work moved up for next rise

We had no problems hemping around the water pipes and electricity wiring. The decision by Paul, the electrician, and I to mount the boxes for the electrical sockets so that they would be flush with the inside of the form work, meant that the only extra work was ensuring that the hemp was well tamped under the plastic boxes and around the conduit. Friday we set a new record, for two workers, getting 20 mixes done.

Saturday we only got 13 mixes done, deeper rises, window sills and more noggins were what slowed us up. We had moved the form work up to level with the window sill on the inside and just below the window sill on the outside, so that we could finish flush with the window sill on the inside and have a downward slope to shed rain on the outside. This made it very difficult to get the hemp in and even it out as the window sills were wider than the noggins. We learnt our lesson - in future we will raise the form work (or at least one side of it) up to about 12 - 15 mm below the sill or noggin, fill that section then raise the form work up and finish under the noggin where it is only about at hand's depth to make it easier to spread out the hemp mix.

Hemping under window sill
Hemping under noggin
The different levels of the sills and noggins has also meant that out rises can not always be even. Where we have had to finish at different levels we have done what we call a "ski slope" angling the hemp diagonally to avoid vertical lines. Where we did not do this at a joint the connection between the two sections of hemp looks weak and slightly less tamped - we will not do this again.

Good join - diagonal
Bad join - vertical
 Hemp building is more like cooking than I first thought. Our problem with the mix tending to stick and be pushed around the mixer was solved by putting the hemp in lightly - just like sifting flour. I originally thought that the sticking issue was due to mixes being too wet or dry, but when we measured out a few extra loads of hemp and stored them in some large buckets rather than the measuring buckets we had no problems with the mix. It appears that the pouring from one bucket to another and the slower pouring in from the larger buckets aerated the mix more, causing it to mix better and take up the water quicker so less leaked out the bottom of the mixer, needing to be re added. This resulted in well combined mixes with less effort.

Second rise done and form work ready for third

Warrain Beach and Lake Woolumboola from the lookout
Sunday morning we moved all the form work up ready for the third rise next weekend. Just to remind us why we are building near the beach we had lunch at the picnic table at Penguins Head Lookout and saw a seal floating around, flipper out of the water, near the rocks.

Seal swimming below Penguin Head

No comments:

Post a Comment