Summer School 2019
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After days and hours of sweaty hard work, long talks, developing prototypes, thinking, rethinking and changing the plans, we finally did it: once again, the Summer School successfully managed to renovate and improve the conditions of a house for low-income people.

A 4th year to breakthrough
First days of August, first days of three intense weeks: 32 students from more than 20 different countries worked alongside fifteen mentors and with a great support from the Critical Concrete team, all united by the same goal: establishing an ecological and sustainable model to refurbish social housing.
The activities were coordinated by four practical mentors: Hugo Dourado (coletivo mel) and Samuel Kalika (CC) on the work site, Ana Antunes (A³-Ateliê) and Gianluca Stasi (ctrl +Z) in the Production Centre.

As practice and theory conjunction is one of our mottos, every Tuesday and Thursday the participants attended lectures by different theoretical mentors, dealing with a huge variety of topics: from architecture and new ways of building to the urban perspective between practice and thought. Thanks to: Marta Horta (Sapana), Antoine Aubinais (Bellastock), Marcela Lopez (Contested Urban Waterscape), Kuc Miodrag (ZK/U), Anja Planiscek, Vincent Pierré (Terranergie), Alberto Rocha (Le Ferry), Bernardo Amaral and Philip Horst (ZK/U) for sharing their knowledge with us!
All lectures will be available soon on our Youtube channel. Make sure to suscribe to stay updated!
The fourth edition of our annual Summer School was slightly different than the previous ones: so far in all the previous editions, we have been working with the welfare workers from the parish of Ramalde, where they helped us to find a home and a family that required an intervention to improve their living conditions.
This year we were pleased to cooperate with the Municipality of Matosinhos and MatosinhosHabit, the public organisation responsible for social housing in the neighboring city, were they contributed with the cost of materials.
For MatosinhosHabit, it was a special opportunity to have one of their dwellings refurbished through more sustainable techniques with a different mindset and to put it back in the social housing pool. On the other hand, it gave us the challenge to work with public housing requirements.
We believe this collaboration shows that the institutions are concerned about the environmental impact of the building process and that they are open to alternative methods to address social housing. We hope this experimental collaboration was the beginning of an ecological and sustainable approach for social dwelling solutions in Portugal.

The house and the goals
The house we worked on is located in the traditional Bairro dos Pescadores (Fishermen’s Neighborhood) in Matosinhos. As its name indicates, it’s an old quarter built for Fishermen and their families during the turn of the 20th century. In recent years, it has been the objective of a strategic plan to revive the neighbourhood due to the urban decay it suffered after years of neglect and fishing industry crisis.
The building dates from the 30s and it corresponds to the standard 2-story typology which one can find in the whole neighbourhood. The house was unoccupied over the past few years and turned into an unhealthy place not suitable for living.
As the statistics indicate, extreme weather and humidity are one of the most critical problems for the inhabitants of Porto and Portugal in general: almost 20% of the Portuguese people cannot heat their houses during winter and 10% live in dwellings with lack of natural light; and the 26.9% live in poor conditions (dwelling with a leaking roof, damp walls, floors or foundation; or wood rot affecting the window frames or the floor).
This house, built without any kind of insulation solution, was one of those dwellings. That’s why the main goal of the Summer School was to turn the building in a comfortable and cozy place to live. For that we set two objectives:
- to insulate the house in an ecological way.
- to provide more natural light in the living spaces.
Applying eco-concepts and prototypes
From an ecological, economic and healthy point of view, we wanted to create a brighter indoor space through the redesign of the interior of the house. We designed two openings in the roof so natural light enters easily, improving the quality of the space. This was done by installing glass tiles within the openings.

Cardboard-lime insulation
Since the beginning of this project, we have focused on developing and researching ecological and sustainable alternatives to build. Previously we were already working with mycelium, wool and cardboard-panels insulation, this year, we started to develop a cardboard and lime based insulation (based in papercrete principles).
The production process of the insulation took the longest, as it was developed purely manually: wetting the cardboard, shredding it, mixing it with sand, hydraulic and hydrated lime and plaster, then applying the mix in the formwork. Day by day. You will have the chance to learn more about the topic (method and recipe) in one of the next articles!

Wool insulation
Besides the cardboard insulation we also used a wool-based technique, made from textile waste of woollen clothes. This type of insulation was used in a new internal wall to create a bathroom.
This recycled wool was kindly provided by Burel, a Portuguese company working with local materials, producing amazing clothes, carpets, scarves, and all kinds of textiles made of wool. If you want to know more about recycled wool insulation, don’t hesitate to read the article on our blog.
Furniture and wood flooring
We also had the opportunity to build some kitchen and bathroom furniture for the people which will eventually live there. The team at the Production Centre made the kitchen counter, as well as the bathroom floor, charring the wood to protect it – see our article about the Shou Sugi Ban technique.
The idea is to burn down the surface of the wood, brush it and then coat it with linseed oil. It is a very interesting process from a sustainable point of view since it doesn’t involve any chemicals. Traditionally used with Japanese Cedar, it has been popularised in western countries in the last decade and also used with other types of wood like Western Red Cedar, Douglas Fir, Cyprus, Pine and Oak. The charred layer on the surface not only act as a triple protection, it also gives the material a very interesting and unique aspect to work with. The 3 protections are:
- Against fire: this might seem counter-intuitive, but since the charred layer is composed primarily of carbon which has a thermal conductivity largely smaller than regular wood, the treated material will take more time to burn in case of a fire.
- Against insect and fungus: the burned wood having no nutritional value to them, this technique helps prevent the propagation of pests and creates a thick protection layer.
- Waterproof protection: the charred layer gives the wood a waterproof resistance.
Traditionally the wood is burned by joining three planks of wood in the shape of a triangle and starting a fire within the created tube. In order to save some time and work more safely, we work with a blowtorch. Once the surface is charred, we then brushed it and cleaned it with water before painting it with linseed oil. This last coating layer, affordable and environmentally friendly -depending on the brand you choose and the eventual added component, helps protect the wood against abrasion and water, and also gives the wood a nice finishing aspect.
The process
Pre-Summer School – Preparatory work with MatosinhosHabit & Nelo
After years of degradation, we found a dilapidated house: trash, dirt and grime everywhere. The first impact was rather shocking, we had a lot of work to start with, but at least almost all the structure was in good shape.
First of all, we prepared the work space before the students arrived: the whole house was emptied by the efficient team of MatosinhosHabit and we had our wonderful co-worker Nelo and his team making a new roof.
Week 1
Once that first phase was done, the Summer School could begin! On the 5th of August 2019, we met our 32 participants from all over the world at Bairro dos Pescadores, where we had a coffee meeting with the lovely neighbours, the MatosinhosHabit team and the Câmara Municipal delegates, as well as some media interested about our educational and social initiative.
After this first contact, all the participants moved to the Production Center, where everything was settled to start with the first presentations and to brainstorm in small groups about the future layout: how flexible it has to be since we don’t know who will live there? What makes more sense: kitchen on the back or in the entrance?…

The participatory design process lasted for three days, taking into consideration the possible future evolutions of the house. We democratically decided to re-organise the house with a kitchen in the entrance and a living room in the back that could grow in the future and we added a new bathroom upstairs.
In order to make the process more efficient and not stepping on each other’s toes, the group was divided in a designing group to finish planning and drawing, and an operative group that started with the hands-on work. The first group was working in our Production Center, drawing and designing the electric and plumbing system, as well as the furniture for the kitchen and the bathroom. Meanwhile, in the Summer School House, the other team had already started to work hands-on: it was demolition time!
One big wall in the ground floor was demolished, some beams were replaced and all the old wallpapers were scratched off. The first week went by quickly and we realised it was time to start building the new walls and making the designed alterations.
This intense first week concluded with a critical tour of the city, that gave the participants the opportunity to learn the deep and hidden Porto guided by our colleagues from The Worst Tours.
Week 2
The second week started in Matosinhos building formworks and the structure for the cardboard-lime insulation.
At the same time, different tasks were carried out by several groups of students: some of them were working in the plumbing installation, others were reinforcing the staircase or making the skylights in the upper floor. Meanwhile, at the Production Centre, the furniture was taking shape.
At the end of the week, the wooden flooring and countertop were ready. We finished the two-thirds of the summer school with a mycelium workshop to experiment with this innovative material and make insulation panels.
Week 3
The deadline was coming and with it also the stress and the work started to get harder. The tasks in the Production Centre were in their final stage and everyday more people were moving to the work site. Once the furniture was completely done, everybody went to Matosinhos where we already got water flowing in the new pipes, the work on the insulation was done day by day and the bathroom upstairs were wool-insulated.
Cleaning the façade, arranging the garden and making more and more insulation… the last details seemed not to end but with the support of the neighbours and the lovely people who surrounded us during all this process we did it.
On the 24th of August, our direct neighbour Isabel Maria Brandão Oliveira Silva cooked us a vegetarian Caldo Verde – typical Portuguese soup, to properly get us ready to the key ceremony with the Câmara Municipal and MatosinhosHabit, Lipor and all the neighbours. Everybody was excited to see the outcome of these three weeks of intense, collective and hard work.
When the second phase of the project in which the students and mentors experimenting and refurbishing most of the house was concluded, the final phase of the house started which was working on the finishings with Nelo and his team and the CC team with wonderful woofers.
After Summer School
This third and final stage has consisted in finishing cardboard-lime insulation, finishing the bathroom upstairs and downstairs, tiling the ground floor as well as installing the custom made windows and doors furnished by Navarra Alumínio and made by Liz D’Arc.
Our partners
All this wouldn’t have been possible without the help of our partners. From logistical help to financial support, materials and tools, we thank the following companies for their more than valuable contribution into the Summer School and their engagement in helping us to build a more sustainable future.

Thanks a lot to all the participants and their amazing engagement without which we couldn’t have carried out this wonderful project!
Nonetheless, we are not satisfied by transforming one house per year, Critical Concrete has been in conversation with several institutions about the next project. Many more of these out-of-condition houses exist in Portugal in addition to a lot of disregarded public spaces. We are setting the next steps, looking for having a bigger social impact. Stay updated for the coming project!