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Building renovation and reconstruction

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For the building renovations, we aim to recycle and reuse existing materials as much as possible, sticking to the traditional building techniques that have kept these buildings standing for however many years it is they've been standing, and sourcing materials as locally as possible.

We intend to work with the buildings substantially as they are, with minimal alterations in order to make them wind and water-tight. The idea is to adapt our lifestyles to suit the existing structures, rather than the other way round. As far as possible, considerations of energy efficiency will inform any changes we make.

Some random thoughts on techniques and materials ...

Wind and waterporoofing

Rather than compromise breathability and the free passage of water through the structures by applying waterproof coatings and installing damp courses and waterproof barriers, we are designing around the buildings to keep the structures naturally dry.

Rainwater run-off, which presently finds its way in by running down the slopes behind the buildings, soaking through the soil and following the solid rock surfaces which form the back walls of the lower rooms, will be caught and diverted before it reaches the back walls. We will be creating open channels cut into the rock itself and lined with cement to intercept the water and take it away, paving the surfaces between the drains and the back wall of the buildings with a slight slope into the drains, and constructing lean-to roofs over the paved surfaces. In this way, we hope to keep the sub-surface sections of the rear walls completely dry, as well as the rock faces themselves.

Timber-framed roof extensions (balconies, porches, stairwells, lean-to roofs, etc) will be used to create sufficient overhang to keep driven rain off the dry stone walls.

This then means that all we have to be concerned with keeping out is the wind, and this will be achieved with a massa of barro, a cob-like paste mixed from the natural clay subsoil found everwhere on the quinta – and which happens to be present in an ideal mix straight out of the ground – which we will use to point the interior faces of the walls. These faces will then either be left just pointed or plastered.

Wall sealant

With breathability of paramount consideration, I wanted to find a sealer for the walls that will be left in clay-pointed natural stone that was not only breathable but as non-toxic and natural as possible. I found various products online, but had the nagging suspicion that there surely must have been much simpler approaches employed in the past. I found some answers in The Natural Plaster Book: flour and water paste mixed into the clay pointing, milk protein obtained from coagulating and separating milk, or the juice of the prickly pear cactus. Not too many prickly pears this far north, but we will be experimenting with the flour and water and casein.

Mortars, renders and plasters

After thoroughly investigating lime-based mortars, renders and plasters, I've ended up with clay, which is the material traditionally used in this region anyway. Clay has some excellent properties. It's a breathing surface that regulates both humidity and temperature, absorbing or releasing water vapour depending on ambient humidity and moderating temperature swings in the same way. Cool walls in summer and warm ones in winter. It's also anti-static and detoxifies the air in a room. It's a mechanical rather than chemical set, so it can easily be moistened and repaired. Any waste can simply be returned to the soil.

Construction

Clay can also be sculpted. Since our original dreams and visions centred around building a cob house, this is something that really appeals. With clay-rich subsoil on-site, we will be using it in some cob construction. There is no suitable space for bathrooms inside the buildings, so we will be building a separate cob bathhouse. This will be attached to a greenhouse in a symbiotic relationship. In winter, bathhouse heat (from a rocket stove water heater) and warm grey water will provide heat to the greenhouse. In summer, solar collectors behind greenhouse glazing will heat the water for the bathhouse.

Insulation

We are using cork insulation for the roofs, sandwiched between rough timber boards covering the original chestnut rafters and a breathable membrane and putting the original roofing material back on top of that: slate slabs for the larger building and clay tiles and slate for the smaller. After some phone calls to a few UK companies supplying cork insulation, I discovered it's manufactured by Amorim, the company which produces a substantial proportion of Portugal's cork wine stoppers and the largest manufacturer of cork products worldwide. Even better, our local builders' merchant now stocks it.

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