Category Archives: Cob building

Windows and Doors

The windows and doors were made by a carpenter in a nearby village who specialises in windows.  They are made out of local chestnut and are incredibly beautiful, as well as super-efficient. There are chestnut shutters on some of the windows, but not all of them, only where necessary.





The south-facing floor to ceiling doors will eventually open out onto a large terrace.  We had hoped to have louvres fitted in between the glass, so that we could block out the sun in the summer and so that we aren’t putting on a show fro A Ponte at night.  However, they are prohibitively expensive, so we have to find another solution.  At this stage of the game, every penny counts!





In Spain they love yellow expanding foam.  You see it all over the  place, even on traditional buildings. Expanding foam contains Isocyanates, such as MDI (methylene diphenyl diisocyanate), which are chemicals that react with polyols to form polyurethane. They can also cause skin, eye, and lung irritation, asthma, and chemical sensitization when absorbed through the skin or inhaled.  They leach out over time into the building.  We have limited the use of hazardous materials as much as possible in our house, whilst having regard to all the other issues – like waterproofing for example. In this instance Mateu was very strict with Javier, the window man, to ensure that no ‘espuma’ was used.  The windows have been nailed and wedged into place and the gabs will be filled with cob.

Some of the windows had to be hand-cut into the chestnut pillars and Javier did a beautiful job on this too.  It has been a great pleasure to work with people who are masters of their craft and I think that they have enjoyed working on such a beautiful project too.  It is still quite rare to build a house like this in Spain. It is not that it is more expensive to build, but it takes a bit longer and people just don’t seem to bother about beauty.  Mateu told us that there were probably only about 50 natural homes in the whole of Spain!

The gap in between the two chestnut lintels has been filled with gypsum, to form a lovely curve that is in keeping with the organic style and theme.  We haven’t gone for the extraneous decoration that you see on many cob houses, it can be very beautiful, but I prefer the honesty and simplicity of beautiful, natural materials, unadorned and worked with skill.

The house is upside-down, by conventional standards.  We have designed it with the living room, dining room kitchen (and a bathroom) on the first floor, with views from every aspect.  On the ground floor are two guest bedrooms and a bathroom, plus and office and store room.  our bedroom as two sets of french doors looking to the north and the east.  There is a very special arched window in the living room, from which we can see the sunset crescent.





Drainage and Waterproofing

Drainage and waterproofing for the house was always going to be a challenge.  The house is 500M down an unpaved track which was a knee-deep river when we bought the place.  One of the first things we did was to dump 26 lorry loads of hardcore onto the track, just so we could drive down it.

To make matters worse, the house is situated right next to the track and is at a lower level!  The storeroom/bodega was a stinking swamp.  We had hoped to be able to knock the whole house down and rebuild it 10M or so away from the track where the land is a bit higher, but that seemed to be impossible according to the zoning laws. The house is considered to be on rustic land, which means there are more restrictions as to what we can and can’t do.

These pictures show the problem:

  • Looking down the track to the house on a sunny day


To make it more interesting, the architects, the structural engineer, Mateu the cob builder and George the German, all had different ideas about the best waterproofing system.  We are finding all the time here that no one actually knows what’s definitively the best; everyone has good ideas and good experience, but the uniqueness of our situation, and what we want to do, means that there is always going to be an element of trial and error.  It would be relatively easy to waterproof the house if we were willing to use a waterproof cement based system, but as we are making the house as ecological as possible we didn’t want to do this.

The corner of the house immediately next to the house was the most challenging.  Even though we are keeping that room as a storeroom that won’t be accessible from the rest of the house, we still don’t want it to fill with water when it rains.  There was no foundation in the original house, just a layer of stones below ground level for the walls.  So we put in a foundation that is about 50cm higher than the original floor at one end and about 20cm above ground level at the back.  The ground floor of the old house must have been quite slopey!

As the north side of the ground floor will be below ground level, as the house snuggles into the hill we went belt and braces on the waterproofing.  First we dug a trench around three sides of the house, all except the south-facing wall which is above ground. Then we rendered the old stone with a layer of lime plaster, then applied two layers of bitumen paint.  Next came a layer of fleece and delta panel.  The fleece was to protect the bitumen from being accidentally pierced by a stone.  French drains were put in the trenches and they were then filled with gravel.

  • Drainage ditch for waterproofing on the northeast corner


We also decided that, as an additional precaution, we would divert some rain off the track.  We hoped that this would make the track more passable in wet weather too – the Concello had already told us that there was no money to pave the track, even though it is a public road.  We weren’t worried about this.  The last thing we want is more tours down the track to see the ‘casa de madera’.  It suits us fine to have the road as it is, but it would be good to keep the area around the house a bit drier, if possible.

When we put the hardcore down we put in a french drain alongside the track.  This didn’t work for long because the track next to the drain got lowered very quickly by the cement and gravel trucks.  The track was lower than the drain before long.  We also found that we needed the rocks that we’d put on top of the drain to build the house.

In January 2015 we dug up the drain alongside the track – it didn’t even work for one winter!  We replaced it with a channel and grate system that crosses the track about 5M up from the house, so that it takes water from both sides of the road.  By this time we had already put in the natural pool so the rain water from the track now drains into the pool.  There is no farming or industry up the track, so the water is clean and it adds to the water flow through the pool.  (There is a an overflow pipe in the pool that drains out to the creek below.)

  • Grate and channel drainage system