This is something you do not need to do, but our experience has shown it is vital you do.
An engineers report is where you hire an engineer to check the property you are going to buy. They give it a thorough run through and also check the property matches the planning application.
We had been told this was going to cost us between €400 and €650 euro, but when we actually called up a guy he did it for €200 and has done an excellent job. (If you need on in the Galway area contact me and I will send you details).
Anyhow - our experience is a bit crap.
Yesterday the engineer rang to let us know he did the report and it was in the post. Apparently the planning laws for large parts of Galway and the West tie new builds to a clause where they must be owner occupied for a number of years (in our case 10). As the house we want to buy is not that old we can't simply buy it. Instead the seller would have to sort it out that they can sell it. So - the relatively smal expense of getting an engineers report meant we saved a hell of a lot of costs later, and so have withdrawn our offer.
There were also some other details which didn't match the planing application so all in all I would highly, highly recommend getting an engineers report.