Building an Adobe Shower with Tadelakt Plaster

Building an Adobe Shower with Tadelakt Plaster

By core team members Nic & Ali

We recently completed another adobe shower and thought we would share with everybody how and in what order it was executed.  The building blocks of the design were adobes that we made with our 2018 apprentices and student groups that visited us through the year.  In total we used around 500 adobe bricks at 5” x 5” x 10”.

What is an Adobe brick?

An adobe brick is mixture of sand, straw and clay, formed in a mold and sun dried.

How to make an Adobe brick

Start by making tests with your soil, if you are not sure what that means, read this article. Where we live we have an abundance of red clay soil. Using our soil, which is almost pure clay, we can use 1 part soil to 3 parts sand as a good starting point, depending on variations in the soil we may need to mix at 1:4 too.  We add about ½ a part of long straw too, this gives the adobes some additional tensile strength.  We then put all our ingredients on a tarp and begin to mix it together. Once the adobe mix is ready (one uniform color of mixed sand and clay) the mixture is put into an adobe form. When packing the forms make sure to fill all the corners! The form is then removed and the brick is left in the sun to dry until it dry enough to be moved and stacked.  In our climate during the dry season this takes 3 to 5 days.

Steps to making a shower

1. Planning

As with all successful projects the key is good planning.  We like to use a program called SketchUp to mock up all of our designs, lay out foundations, the frame and even plumbing. Every detail must be planned in advance this makes sure that the correct provisions can be designed in and made in advance.

2. Foundations

For our shower we used concrete blocks cut in half so that they could form the curves that we wanted. A shower is going to be a wet area so it is important that you think about this during the planning stage, where will the water drain to? Are my pipes embedded in my foundation? How is my roof going to be attached. In our design we decided to have a separate Timber Frame to support the roof structure.

Step 3 - Adobe

The first course of adobes were attached to the foundation using a cement based mortar this helped them bond strongly to the concrete foundation. 

Step 4 - Bond Beam

From the second course upwards we used a sandy clay mortar for the adobes.  Every 4 courses of adobes we made a cob bond beam for extra strength.

Step 5 - Gringo Blocks

Wooden hollow blocks (known as gringo blocks) were put at the end of each wall to attach in the wooden frame for the doors and a hollow plumbing box was installed where all the plumbing would be inserted for the shower handle. In Costa Rica the plumbing parts easily purchased in the local hardware store are terrible and always leak so we made most of the plumbing accessible from the outside. It is generally a good idea when making your initial design to plan for replacing parts in the future.

Step 6 - Frames

The door frames were installed at this point and they were screwed into the Gringo blocks.  The door frames were also tied into the adobe structure using some mesh, we used what we could locally find which is what they sell for chicken fencing. You could also use a variety of natural alternatives, attaching them to the wood and plastering them in to the wall to give them extra stability.

Step 7 - Leveling

A leveling coat was then applied to sculpt and level the walls, this was tied into the door frame to give extra support too.

Step 8 - Tiling

The vertical surfaces of the concrete block were tiled to provide a plaster stop on the bottom edge were the plaster would meet the tile.

Step 9 - Plastering

A lime base coat was then applied over the earthen leveling coat. Whilst this basecoat was still damp (before it started wicking moisture again) we applied the tadelakt mix (1 part fine lime sand and 1 part lime).   We did the Tadelakt like this as we had such a large continuous surface area to plaster and needed the time to work it all.

Step 10 - Tadelakt

Once the plaster had dried enough we stoned and soaped the wall using our homemade soap.  The Stearic Acid in soap reacts with the Calcium Hydroxide (hydrated lime) to make Calcium Stearate which is highly hydrophobic and one of the reason Tadelakt is considered water resistant. Read more about Tadelakt here.

Step 11 - Mosaic

The remaining horizontal surfaces were tiled using different colored swimming pool tiles.

Step 12- Exterior Plaster

We used some of our left over mixes to do a base coat and finish in one pass, adding some pigments to alter the color. We used floats and darbies for the base coat and a sponge float and flexible Japanese trowel for the finish

The shower was ready, once the plumbing was connected all that was left to do was enjoy the cool water in these wonderful showers. The two sides of the shower are pretty similar, the main difference being the color combination on the tile mosaic floor. Do you want to bathe in this epic outdoor shower? Come stay with us at Bernies Bungalow!

want to learn more?

Dream of building your own home, outdoor space, or maybe just a simple earthen garden bench?

With over 15 years of experience building and teaching natural building techniques, the Ranch is a perfect setting to get inspired and hands on learning.

Join us for one of our upcoming natural building focused workshops. We generally host a workshop in natural building, timber framing, and/or bamboo construction annually.

Design Ideas for a Sustainable Home in the Tropics

Design Ideas for a Sustainable Home in the Tropics

By Nic & Ali,

At Rancho Mastatal we have been building sustainable homes from natural materials in the tropics for over 15 years. In this time we have tried many different styles, building materials, and designs. We would like to share with you our opinion for the best natural and sustainable home design for the tropics.

For examples and inspiration view our structures here.

We have found that the quickest, cheapest, and most aesthetically pleasing building style consists of a reinforced concrete stem wall foundation, with a timber framed structure, a Dutch gable roof, wattle and daub walls, natural plasters, and an earthen floor. These are the reasons why we chose these methods:

·       Reinforced concrete stem wall: resistant to earth quakes and provides good access around the entire house to spot any invading termites.

·       Timber framed structure: beautiful and utilizes an abundant and quick growing resource in the tropics.

·       Dutch gable roof: provides good protection to your earthen walls on all sides, and allows good ventilation of the roof.

·       Wattle and daub: utilizes an abundant resource of bamboo as the wattle, and the thin walls of daub are fast, efficient, and cheap to install. Provides privacy, security, and protection for your home. 

·       Natural plasters: a logical plaster to put on top of an earthen wall.

·       Earthen floor: a perfect combination with a stem wall. Utilizes natural and abundant materials. Far cheaper than concrete or wood floors.

Other design considerations to include in your sustainable home are the following:

·       Trees near building site: this is a double edge sword when it comes to building. You want the shade provided by trees, but the risk of them falling on your building is worth considering too. And their root systems can damage your foundations.

·       High and insulated ceilings: increases construction cost slightly, but the extra space in your building creates a more comfortable temperature.

·       Large overhangs: provides additional covered space around your building, protects areas from the sun, and is essential to protecting your earthen walls from the rain.

·       Air flow and fans: depending on exactly where you are, even with a well-designed house you may need the addition of a ceiling fan.

·       Covered drying space: always a benefit when it’s raining!

·       Outdoor and indoor spaces and screens: it is nice to have spaces that are screened off and those that aren’t so that they can be taken advantage of at different times of the day and year depending on the heat, bugs, rain, etc.

·       Orientation: think about where you spend most of your time and orientate those spaces to the best views. Also consider where the sun rises and sets and how that will influence the temperature in your house.

·       Water run-off and drainage: make sure to have gutters on your roof and move water run-off away from your foundations.

·       Road access: pretty essential to getting anything to your house! Examples: building materials, groceries, etc.

These are some great pointers to start generating ideas of what you would like your house to look like. At the Ranch we are interested in empowering individuals to develop the skills to build their own dream home. If there are some things that we have forgotten please let us know in the comments section!

want to learn more?

If you think this is an interesting article and you are interested in green living and designing your own sustainable home consider joining us for one of our annual workshops. Generally we host a Timber Frame Construction and Natural Building & Plasters Intensive . We will also have lots of other amazing workshops focused on the subjects of sustainable living. See our website for more info!

Re-plastering: What will be unveiled?

Re-plastering: What will be unveiled?

On the building list, one of our goals is to correctly re-plaster old structures to enhance their look and highlight our unique architecture. Over the last couple years we have slowly been giving our old structures new face lifts. Using lime plaster techniques that we have been learning, practicing and perfecting, we have transformed various run down plasters into beautiful canvases of art.

This process of remodeling never fails to reveal a variety of problems and headaches. We have learned that you never know what will be exposed once you start to take apart a wall for re-plastering and patching. So, as we have been going back to old structures to prepare for a face-lift we have encountered many different troubles due to past techniques.

In order to apply a new lime plaster you must remove all material from the wall that seems loose or may not allow the lime to adhere well. This is done by chiseling off old plaster materials, which can lead to more of the wall falling apart than planned. Once you’ve taken off the old materials you must go back and fill in the gaps created in this process; which can be a lot of gaps! The quality of the original wall is a big determining factor in how quickly (or not so quickly) this whole process will take. Therefore determining the amount of time a project will take is extremely difficult; you can make an estimated guess, but depending on what you uncover the estimate can change drastically. As in any remodeling job you just never know.

You can tell the difference between the walls that were built patiently with skill to those hurried by the physical amount of material falling off. There are a variety of reasons why there is so much variation in the quality of our walls, but we believe it is mostly due to the transient workforce that was utilised to build many of these structures. High school groups, short term volunteers, and so forth have built much of our campus. Lessons learned during one construction project were not always carried over to the next due to this lack of consistency. It resulted in a huge variety of quality and decisions were made that in reflection were not the best.

During our long evolution we have tried many different earth building methods, mixtures, materials, and tricks with varied success. For example, our previous wattle and daub methods used little bamboo wattle support meaning that the earth mixture didn’t have enough support and the walls ended up being a little wobbly. Now we have moved to weaving many bamboo strips between the uprights, spacing them about one half inch apart rather than a few inches. Our earth mixture has changed through the years as well, experimenting with the ratios of clay to sand, the additions of manure, different straws, and other materials that we were told would make the mix better. We went through a phase of adding manure to our earth mixes and applying a “poo schmer” as a plaster. Looking back the additions of manure possibly led to a weaker final mix and the schmer although an effective plaster was not ultimately what we wanted aesthetically. It has since proven difficult to remove in order to apply a finish that we actually want. We didn’t realize the importance of compressing the edges of your walls, which have resulted in cracks around the edges of our wattle and daub panels; or the importance of bridging between two different materials (eg. wood to be covered by earth).

Over the years there have been many different techniques used and we believe for the moment that we have developed the mixes, techniques, and materials that get the job done efficiently and create great looking walls and structures. Among other plastering projects the main one for this year is to re-plaster the Casucha inside and out, using a method called “poor man's” tadelakt on the inside and a sponge floated exterior. Stay tuned for pictures of the finish!

Ali O​