Breathable Paint

Ever wondered why you are forever painting things?  You re-paint the windows, only for the paint to crack and peel a year or two later.  Paint is like all other materials in our breathable home.  If it's plastic - Dulux Weathershield or something like it - it's plastic.. It can't breathe. Timber sweats underneath it, tries to lose moisture content, and can only do so when it manages to blow the paint away.  By this stage it's probably rotten too. Sometimes it comes off in sheets.  Sometimes it goes bubbly from trapped moisture behind the paint. Manufacturers make all sorts of silly claims about breathability and then say that it keeps your timber / wall / stone or whatever, completely waterproof and dry. Somehow it's magically 'microporous' but it keeps water out.  Something of an oxymoron I think..    

So - in short, the things NOT to use on your breathable house:

Plastic paints - most mainstream paint manufacturers are making plastic paints - whether it's gloss for the doors and windows, emulsion for the walls, or masonry paint - it just is not breathable.  

There is also a whole class of 'masonry coatings' - things like Pliolite, Sandtex, Kingfisher, Stormdry - all of these are advertised as Waterproofing Paints or coatings - and some even have nice BBA certificates which give them an air of credibility.  They all will try and tell you that in addition to waterproofing, they allow the wall to breathe.. We experience these coatings on a regular basis when we are doing surveys - and our opinion of them is based on the damage we see.  Avoid  them.  You should NEVER coat a wall with anything unless it is a breathable, sacrificial coating like limewash.

Breathable paint does exist.  It takes the form of clay paint, which is a breathable masonry paint I guess - made from natural clay with minimal binders, it is thick, almost like a limewash, but gives better coverage and crack filling. It's not suitable for exteriors though - for that, you need to stick with limewash.

There ARE a breed of silicate paints, mainly from Germany, which claim to be breathable.  In our experience they are not - and we've had a lot of trouble with them peeling - but the manufacturers still claim they do the job.  

Finally, there is a whole world out there of linseed paints - brilliant for exterior timber - which are now coming of age in terms of commercial development.  They are readily available in the UK - we recommend them all the time, and have used them ourselves extensively.  Linseed paint - remember it - it's brilliant stuff.