Daniel Attwell

Its my first post so please be gentle.

Hi

Location: La Alpujarras, Granada province, Andalucia, Southern Spain

Some info first: we live in the Alpujarras, Southern Spain and we (I say we but its mostly been build by builders! we will help too) are renovating an old goat shed and making it into a two floor house to live in. It's originally made of stone with a flat roof. We would like to build using traditional local building styles but for the first floor it was hijacked by a 'bio construction' builder and it got out of hand....anyway.


We now start on the second stage after the summer break and we are searching for bio construction/natural building materials and techniques to construct the first floor floor with. Clay, sand, straw, mashed up hemp? But we need to have the perimeter of this floor in concrete as this will provide the support for the pillars which will sit the roof.

Now, the layout of the house is like this. ground floor has a concrete floor (yes, I know, sorry) and it uses a combination of large bricks (also, sorry) and original stone. The building was in bad shape and it needed to be reinforced with steel rods, steel beams etc (the conventional building way) but now we are changing back to the original plan. A bio construction house.

The other thing of note is that after the first floor has been constructed we will probably need to use modern and traditional techniques to make the floor.
Why? The floor will probably (yes a lot of probablys as we are still consulting with conventional and natural builders) need a concrete perimeter and the central part natural to balance the. The concrete perimeter (does it need to be concrete?) will support the pillars which will hold up the roof.
But my rational is that the two different material (concrete perimeter and natural central floor) will shrink at different rates and cracking will occur. This is no good as we will put tiles on top of this.

Plus, how do we get around not using concrete (or reducing the amount) when building the roof. It has to be a flat roof due to local laws.

We are asking for your experiences, ideas and practical advice on the matter.

Many thanks
Daniel

Post 16/04/2025 08:25:39     Subject: Cob house flooring and moisture barrier
I’m working with a natural builder renovating an old stone house at the moment. The first floor was mostly compacted earth and had moisture issues.
We dug it out about 40cm, will put down sharp gravel, then a slab of 5cm lime and sand and hemp mix. The gravel should break the capillary effect for rising moisture.
On top of the slab we will tile or put wooden flooring.

Hola Benjamin

We are in very similar circumstances as you. We are renovating an old stone 2 floored Alpujarran house and need some fresh ideas for materials to use on the second floor. Unfortunately the ground floor was built with concrete and a plastic moisture barrier but we want to change the next stage of building to bio construction. We also nee to build the roof and pillars to support this.

So my question is what materials can you recommend to use on the second floor floor. In order to support pillars a perimeter of concrete might have to be used as a strong foundation and then bio construction materials for the rest of the floor but will they shrink and crack at different rates? 2 possibilities for floor material might include
arcilla expandida, lime, sand, and cement. Or the other option is sand, cal and ground hemp.

It would be great to hear some of your own experiences and the materials you used.

Many thanks
Daniel