Buried and Planted

I now realise that peoples area's of expertise extend only as far as the product they sell. We went off to a local company to help us deal with the poorly finished roof and specifically our concern that it may leak. This was motivated by the fact that we noticed a small 'stabilisation crack' appearing in the roof. The proposal was to seal the roof with a 10mm cementitious waterproof layer that would properly bond to the concrete roof. This is effectively cement with a waterproof additive and I did not understand the difference between this product and the 100 cubes of cementitious concrete with a fancy waterproof additive that we had already laid. But of course it was being supplied by someone different so it was sure to work. However we needed a smooth finish for this product, something we did not have. Also it was prone to crack - just as we had experienced so there was no guarantee. In the end we went for a paint-on bitumen layer - or rather several layers which is flexible and if not exposed to the sun, would last a lifetime. Well let's hope it lasts my lifetime at least.

We then agreed to lay down some 'Biddum' onto which we would lay the crushed stone. This would protect the bitumen layer from damage. Another layer of Biddum would be laid onto the crushed stone which would separate our drainage layer from the top soil. The Biddum would also prevent the roots of the plants from reaching the concrete. Our intention was to purchase a roll of the stuff and obviously cost is an issue, so we were going for the thinnest option. However, Philip who supplies us our earthmoving equipment had some lying around his yard from a previous job that he kindly supplied to us at the cost of the cheap stuff. When I compared it to what we were planning on using, I realised that we had almost made a big mistake.



Poen then installed his solar frames and the plumber connected them up. We used 28mm copper piping to supply the solar bank and this we insulated with lagging generally used by airconditioning installers. The frames are a bit of an eyesore, but I've grown used to the sight of them and in the end, I know the plants will eventually hide them.


Finally we were ready to start loading the crushed stone and soil, something that we considered to be a major milestone. It needed around 30 tons of crushed stone and then even more topsoil. Obviously this could not be loaded by hand and we brought in an excavator, the only bit of local plant that had the necessary reach. Being a fairly large machine, it does not have the finesse of something smaller so we ended up with a bit of soil mixed in the stone. I feel that this may need a few good rains to wash out the loose soil but only time will tell. On the other hand, it could in fact be a benefit. Fortunately this progressed rapidly with the whole crew moving and spreading the stone as we went. This was again covered with Biddum which made it look as if we had made no progress at all.

We had separated and collected the topsoil from when we first broke ground. This had in the meantime become overgrown with a variety of grasses and lay unnoticed for some time. We were concerned that we did not have enough, however we were surprised by the quantity we had available. This took quite a bit longer to spread than did the stone and had to do with the fact that we put on quite a thick layer.

The roof is designed to carry 450kg/m2 with a significant safety margin and we estimated that we loaded half of that. It is unsafe to load the roof to its limit due to the fact that the water retained in the soil from a rain could add anything up to another 80 odd tons to it. That's obviously presuming it becomes fully saturated.

Just to be different, we collected some rocks to make a rockery. Some of these were quite large and Midnight was dreading having to carry them up the ladder and was pleased to see them so easily lifted by the excavator. He and John then set about laying them out and digging them in. The rocks look far more natural if they are dug into the ground rather than planted arbitrarily on top of it. We tended to place these rocks over the ringbeams where we knew there was maximum strength. The rockery allowed us to create islands of fairly deep soil where we were able place plants with a deeper root structure. Generally we have covered the roof with succulents all of which can exist on very little water. These we have been propogating in our vegetable garden over the past few months and Johan kindly donated some aloes' and 'hen & chicken' to add some additional character. We will maintain just a small section of the roof as a garden and will let the rest grow wild where I'm expecting a variety of grasses to establish themselves. However without the soil depth they are likely to die back at some point and this is where the succulents will have to come to the rescue. Again, this is pioneering stuff for us and we have no clue as to how things will finally develop on the roof. But it will develop its own equilibrium which will be just fine.

To help the plants establish themselves, we set about irrigating the roof which in itself was quite an odd idea - irrigating a roof! Many people have asked how we intend keeping the soil on the roof. I've been convinced that a combination of gravity, plants and natural compaction keeps most soil in place so this did not worry me much. Well the saturation was a good initial test and it drained properly through the rainwater harvesting channels and through our edge drains. The soil did not slide off, run off, nor wash off!! But then of course a Katrina event may be different but then it certainly won't lift off - at least not all 400 tons of it.

Dawie's unsupervised, unprepared, irresponsible crew set about removing the roof supports inside the house late on Thursday evening. Andrea called in a panic expecting them to damage the walls by what was a complete lack of care in their manner. Despite promises to her and later to me that they would be careful, they did manage to leave gouges in various walls. My instinct was to get them to leave and to only return under supervision but I didn't and now I will be forever reminded of their utter incompetence by the many marks that were left in their wake.

With the props removed, we have begun to prepare the floor. It has been treated for termites and we are busy compacting the layer of 'G5' material in preparation of the polystyrene slabs. It is currently a large open expanse that is flooded with light which is fantastic. Now that the motley Nouns are almost behind us, the road ahead looks promising indeed. We have a unique shell of a house that is the pride of Johan and his crew and one that impresses every visitor of which there are many. And it still impresses me every time I see it.