The IEI contract would not be suitable for building works - it is aimed mainly at civil engineering works (roads, bridges, etc). The RIAI publish a domestic form of contract known as SF 88 (Short Form 1988 - I'm not sure if this has been updated recently - the RIAI website should clarify this) - it would be useful having a professional like a surveyor or an architect to administer this contract. It sets down the main elements of a building contract - the parties duties / rights, insurance, variations, etc.