The Styrofoam House

So much is going on in our life at the moment that it’s been a while since I’ve updated you on building progress.  The current inter-disciplinary mayhem of the last stages of construction makes it near impossible to focus on one theme, but there is one funky house finishing process I want to tell you about.

Horizontal Rain

Some people say the rain comes at you horizontally here in northern Portugal and I can confirm that this is no exaggeration.  The charming country houses everyone admires in summer become perpetually damp, mouldy and cold in the wet season.  So, having witnessed the effects on walls (cold and mouldy), clothes and shoes (shades of white and green mould), moods (decidedly blue) and toes (cold and blue), we’ve chosen to investigate ways to minimise damp, make our house more energy efficient and especially to keep my toes warm.

Managing Heat Loss

Heat loss is a major issue not only when it comes to paying escalating energy bills, but also when it comes to the health of a home and daily comfort levels.  Depending on the way your house was constructed, between 35% and 50% of its heat is lost through the walls.  In the past several decades, the use of cavity walls (two layers with space between them) has been one of the most common ways of insulating, but many solid wall houses have received little to no insulation.  These days building practices point in a new direction – external wall insulation.

Putting on a Coat

When humans are cold, we don’t simply put on another t-shirt, do we?  We go for sweaters and raincoats and scarves.  So, to find a comparable solution for a house exposed to some heavy weather, we opted for an External Wall Insulation (EWI) system from a company called Saint Gobain Weber (yes, the French have more to offer than baguettes and attitude).  Locally the system is referred to in short as “cappotto” – Italian for “coat”.  To put it in our architect’s words, our house is essentially “putting on a coat” and to qualify that further – “a well-tailored coat”.

How does it work?

In short, insulation is fixed to the exterior walls and is covered with a render to further weatherproof the wall.  A gazillion product solutions are on offer(including an anti-fungal layer, a huge benefit in a damp climate), but ours is a mixture of weber.therm classic and weber.therm pro.

Once the exterior wall, whether brick or concrete, has been given a basic coat of plaster, a series of insulating layers are added:

1) Polystyrene Insulation tiles (glorified styrofoam in my book).  There are differences in thickness for different solutions, but for our house a white Styrofoam is used for normal areas and a higher density blue layer for colder, damper areas.  Both are about 4cm thick.
2) A finishing plaster
3) A mesh fibreglass net that acts as reinforcement
4) Various base coat renders, depending on the solution chosen for your home.
5) Top coat renders – the paint gets mixed in with the top coat so that it is applied in one final step and the house doesn’t have to painted once insulation has been completed.

I don’t want to sound like a naive tree-hugger plugging a product here, because the cost isn’t insignificant, but if you can consume less electricity and consequently reduce carbon emissions and have a comfortable and healthy home, this does seem like a reasonable solution.  I will report back on toe temperature when possible…

A few other random facts:
– Weber’s EWI system has an expected life span of 30 years and is guaranteed for 10.
– Costs vary, but the company’s UK site provides a rough estimate of 6,500 -7,000 GBP (7200-9000 euros ) for a typical 3-bed semi-detached house.
– Other suppliers of this kind of a solution include Knauf, Fassa Bortolo, Nordtex and others.


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