Exterior Rendered Walls - Best Finish ?

[garrardrj]

We have a 1920's built house that has been extended and is fully Rendered all round . It is smooth rendered finish and has to be regularly painted , which is not an issue . The issue we have is that it cracks regularly and is letting in the water , to the first skin (The newer walls on the exterior are thremalite blocks - very porous !) We want to fully weatherproof the exterior and wondered what others might suggest , is there a flexible finish that will absorb minor expansion and shrinkage that occurs . It is mainly on the wall that faces directly south and gets hit really hard with wind/rain and also dries out fully as it faces the sun for the majority of the day .

Wallshield - Is a waste of money and just glorified painting !
Render - Has not been very succesful
Tyralean - Will it stop the cracking and water ingress ?
Is there another finish i am not aware of ?

Any builders on here , what would you do ?

Any advice welcomed 

[rich83]

Is it the paint that is cracking or the actual render?

[garrardrj]

Is it the paint that is cracking or the actual render?

The Render , we have had it repaired twice !

[MattPoss]

A lot of buildings we do now are finished with K Rend, good quality stuff and very popular...............

http://www.k-rend.co.uk/default.aspx

[Matto]

I believe can also get coloured renders aswell so you won't have to paint it afterwards.

[Pikey Motorsports]

K Render but it wont be cheap