Gunia is a way to check perpendicularly of walls or boundaries. Suppose you have two walls meeting perpendicularly, but you want to be precisely sure that the angle is 90º. So, what is generally done is, from the corner a point at a distance of 3m is marked on one wall and that at a distance of 4m on the other. Now, according to the Pythagorean theorem, the distance measured between these two marked points has to be accurately 5m got the walls to be perpendicular. And that’s what we wanted to check.

Dean Richards
Building control officer