Hairline Rendering Cracks!

[alan589]

Hello
Our house is rendered or roughcats as it is sometimes known. The house is 7 years old and the rear elevation has many thin cracks in the rendering. The House Builder came out and suggested that it was thermal cracking and was our problem.
This seems odd as it is only really the back wall that is affected. Surely thermal cracking would affect all the walls which then points to another reason. Can anyone help me find the cause?
Ta
Alan

[moger4]

this may well be the problem as your back wall maybe south facing
scrape the cracks out and fill , some kind of sealer on the render is good also