Breathable external paints

dllive

Hi all,
I have a cob cottage. Looking to get the outside painted. Obviously crucial to use a breathable paint. What the most cost efficient breathable paint to use? Sandtex do a breathable paint, but I dont think its truly 'breathable'.
Is there a lime based paint that doesnt cost the earth?
Thanks

FreeBear

Please, don't use Sandtex on a cob house. You could try giving someone like Mike Wye a call to discuss options.. Personally, I'd go for lime wash - This is so cheap and easy to make yourself if you have a tub of lime putty. See the bottom of this page - https://www.limebase.co.uk/guides-to-limes - Add a drop of linseed oil if you want to increase the waterproof properties (no more than 1%)

A word of warning - Not all lime putties are the same. There is a variation in colour. For example, Singleton Birch is a soft butter milk colour, where as the Ty Mawr stuff is distinctly grey.

ceredigion

Do some research using the term, Silicate Masonry Paint

dllive

Thanks guys.

Surely its scandalous that Sandtex market their paint as 'breathable' when its not!! Had I not posted on this forum I would have used Sandtex thinking it was suitable. (Now knowing that becuase its plastic-based it is not breathable at all!!!)

Unfortnately I dont have the abiity to mix my own lime wash, or do the painting. So will have to buy lime wash ready-made (or buy silicate paint).

Im presuming silicate paints and/or paying a painter to use these materials is vastly more expensive than a 'normal' painter using a 'normal' paint?

FreeBear

dllive wrote: »

Unfortnately I dont have the abiity to mix my own lime wash, or do the painting. So will have to buy lime wash ready-made (or buy silicate paint).

If you (or your painter) has a bucket and stirrer, it is real easy - No harder than mixing pancake batter or making a cup of coffee. Applying limewash is not as easy as slapping it on and leaving to dry. It needs to be brushed on in thin coats or else it will crack and flake off.

Silicate paints are a little more forgiving and can be treated the same as any other paint. More expensive than limewash, but does have a much longer life.

Niv

dllive wrote: »

Thanks guys.

Surely its scandalous that Sandtex market their paint as 'breathable' when its not!! Had I not posted on this forum I would have used Sandtex thinking it was suitable. (Now knowing that becuase its plastic-based it is not breathable at all!!!)

Unfortnately I dont have the abiity to mix my own lime wash, or do the painting. So will have to buy lime wash ready-made (or buy silicate paint).

Im presuming silicate paints and/or paying a painter to use these materials is vastly more expensive than a 'normal' painter using a 'normal' paint?

FYI - when you buy lime paint from Limebase it is just the powder in a paint bucket, you just add the water.


edit: give limebase a ring, they are a helpful bunch.

dllive

Thanks for all your comments. Very helpful. I should say that I cant mix lime becuase of a physical disability (dont want you thinking its because Im lazy! )

Ive done some googling and it seems lime wash is cheaper but more laborious to put on (needs 5 - 6 coats) whereas silicate is a lot more expensive but goes on in 2 - 3 coats.

Im veering towards a silicate paint becuase of its durability (one side of the house gets a battering during the winter). So I guess the question is - wheres the cheapest place to buy silicate paint.

Apodemus

As above, just mix your own limewash. (I’d go one step further than FreeBear and suggest that it is just as easy to make your own lime putty first!). Your only problem comes if you have your heart set on a particular colour other than white. Reliably and consistently mixing enough matching limewash for the whole job could be a challenge.

dllive

A local deocrator has mentioned AllCoat Exterior Matt. He said its water based and is breathable. What do you think? Thanks

FreeBear

Sandtex also claim that their masonry paints are "breathable". But no data is provided for vapour permeability by either Sandtex or Zinsser. In the absence of any hard data, I would take claims of "breathable" with a pinch of salt.

The long term consequences of using the wrong coating on a cob wall could be very, very expensive. Several cob buildings have collapsed in the south west as a result of inappropriate coatings. If your house is listed, any mistakes could cost even more to put right.

If in doubt, have a chat with Mike Wye - Apart from the cost of a phone call, what have you got to lose.

dllive

Hi guys. Just reigniting this post: My decorator has recommended Zinsser All Coat Exterior. Is this breathable and suitable for cob/lime plaster ? Thanks