My most optimistic view was to have the roof up and curing over this period, but the rain put paid to those hopes. So we moved up to the shed area and began ramming the shed walls. We made significant progress and managed to put up most of the walls. Now that we
can experiment (it's a shed not a house), we have tried a few alternatives. Firstly, we have not built the concrete pillars and are ramming the walls first. Then the intention is to cast the pillars - after the walls have cured and finished shrinking. This means that we do not have two plumb structures (the pillars) to which we can attach our formwork that used to make the set up easy. Now we have to invest quite a bit more time in setting up the formwork ensuring all surfaces are vertical. After this, we then support it to prevent it leaning during the ramming operation. As usual and despite our best efforts we did not get it right the first time and have now reverted to using several strategically placed plumb-bobs, something Johan was surprised were available in the shops. I think his grandfather last built with them. But now we can check our set up quite easily and can instantly notice shifts during the ramming process.
The shed walls are much longer and cannot be rammed in one go. We have now tried passing the clamps through the wall cavity. Before, our clamps were passed through the concrete pillars as holes in concrete can easily be plastered over. Now when we remove the form work, the pipe clamp holes in the rammed earth are clearly visible and where the walls join is a reasonable chamfered line. I avoided this for aesthetic reasons before, but now having seen the result 'in the flesh' agree that this is a most acceptable option.We have continued with the new wall treatment that seems to leave the walls stronger. Also, cracks are no longer a concern to us. We seem to have mastered the curing process and prevented any hint of these. The longer wall spans have resulted in small lifts (the fixed volume of earth in the bucket is spread over a longer span) which in turn have resulted in a fine quality finish. This is certainly something else we will include in future projects - far better lift height management.
As an aside, quite a few people have paid us a visit to get a glimse of this project. The staff are quite proud of their work and a pecking order has now developed. The fitness levels are such that the ramming crew does not want to be relieved and now entire walls are built by the same crew. Pushing a wheelbarrow or sieving sand just support the main event - which is ramming the wall, where the gods of the rammed earth wall work.Rain continues to plague us. The rain gauge has not been emptied this year and again it overflowed - so we've had over 100mm in two weeks.
However, when the site is too wet to proceed with the walls we focus on the garden. Growing vegetables and the 'veggie garden' is as important as any other part of the project. We have now terraced the steep bank behind the house, something that is nearly finished and all of our veggies will literally be within easy reach of the kitchen. We've dug out the subsoil and replaced it with a good mix of compost and topsoil and the beds are ready for planting. Other than being a great veggie patch, it will make a great mini-amphitheatre for home movies, inspirational talks, weddings and funerals. And you can make a salad while you wait.
We've also begun planting the rest of the bank creating a rockery out of all the large rocks that have been dug up at various stages of the project. I purchased some more succulents that will work well on the roof. These I'm hoping to propagate and mature so that the nasty concrete finish will disappear behind a variety of water-wise plants. John has already split many of them and has begun planting them in the vegetable garden where they will rapidly grow to a thick cover. When the roof goes on, they will be transplanted. And this nicely brings me to the issue of the roof...
The roof has a seven degree pitch. It's not much but it's not horizontal and this has to be mounted on a flat rammed-earth finished wall. This results in the roof resting on the back edge of the wall with a 55mm gap at the front edge of the wall. Since it's critical not to damage the wall, which includes no drilling or fixing with nails means that this little issue becomes quite a big one. Also, the chamfers need to be finished off nicely which requires a bit of patience and thought.Our initial intention was to build a concrete ring beam (as is shown in all the rammed earth books) but were unsure how to deal with this detail. We would have to had included reinforcing but the roof design had not been finalised - so the question was how much reinforcing? Had we done this, we would have had a finished, hard surface properly aligned to take the ribs. Obviously at this point we should have had a roof design which would have included this detail but we didn't. Even when we finalised the design, there were no architectural drawings showing the detail of how the roof would be installed and when I raised the issue, it was not really considered an problem. The engineer sent me a hand sketch of how the ribs intersected the upstand beam and this was the best detail we had. Being fairly concerned, I subcontracted the roof installation to a roofing specialist. This was a cop-out really, but meant that we could work on the shed whilst the roof was done.
Dawie the roofing specialist arrived, spent a day or so on site planning, issued his instructions and then left. I then annoyingly watched the lack of progress over a period of a week. It was an unsupervised calamity waiting to happen. Well the roof went up - a bit of it anyway. The ribs and blocks were installed but the contact point between the roof and the wall remained a problem and all the ideas in search of a solution were a poor compromise. It was then jacked in the middle to help support the load which reduced the load on the walls. Well a 7 degree pitched roof standing on unsupported jacks, resting lightly on the walls is of course a collapse waiting to happen. And it did collapse. The whole structure just slid 'downhill' and all the supporting jacks happily crashed into my previously pristine wall - the one we had knocked down and rebuilt. Well there was a bit of tension in the air around that time which could have been described as a fog - visible and chilling.
I insisted that the roof be removed and Johan and his team moved in to build a ring beam finished at the correct gradient. The roofing labourers left the site and the engineer was called to site. Since this is the most expensive roof on the planet (as far as I'm concerned anyway), I was very tetchy when he called for more reinforcing in the ringbeam, onto which we would install our roof and upstand beam. That idea got nuked and now our upstand beam is 3/4 upstand and 1/4 downstand and we're using the reinforcing that was specified in the original beam. Now for a simple rammed earth rule: upstand beams should never be married to rammed earth walls on a pitched roof. Another good reason for ring beams is that they are easily accessible and can be done with care so vibrated concrete does not end up running down the walls.Today we cast the downstand portion on the south wall with all the chamfer detailing. Tomorrow we will know if it was a success. Hopefully by the end of the week the north wall will be done. Then the upstand beams will be done together with the roof by the roofing contractor, which is the easy work. Simple solution, but one that should have been provided by the professionals and not by the client.
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