Like most people with any kind of life, I've never taken much interest in plasters and renders. It's just stuff that covers walls (or something). Goes under paint, preferably Farrow & Ball, innit?
These days, however, I know a tiny bit more about plasters and renders - although admittedly, not so much as to make anyone (even the most unambitious DIY-er) feel threatened. This picture demonstrates why: Tim is currently plastering the walls in our kitchen/living room, in what I am reliably informed is a 2:1 mix of natural hydraulic lime and fine sand.
What I do think is interesting is the theory behind this choice of mix. Basically, modern builders have Got It All Wrong here (and I borrow that opinion wholesale and without apology from the hugely informative but perhaps uninspiringly titled, Using Natural Finishes: Lime- & Earth-based Plasters, Renders and Paints).
The theory goes something like this: Buildings should breathe. Ideally, they should breathe moisture: both moisture that's created externally (for example, rain) and moisture that's created inside (for example, kettle's on).
Most modern buildings are not designed to deal with moisture well, but rather to be sealed off against it. Not only does that approach trap internally created moisture (cup of tea in a damp environment, anyone?) but also involves the use of all sorts of nasty synthetic materials.
So natural plasters and renders , which are more permeable and more green, are clearly the way to go - especially in houses like Casa Cecilia, where the entire downstairs is made of natural stone. They minimise the moisture that gets in, while allowing excess moisture created internally to escape.
I love the idea of our beautiful house being able to breathe.