Alle Firmen mit dem Anfangsbuchstaben I
- Ing. Niedermeyer Werner
- Ing. Nieschlag Robert
- Ing. Niesner Oliver
- Ing. Nikola Tomic e.U.
- Ing. Nikolay August Christian
- Ing. Nikolic Isabella
- Ing. Nindl Bernhard
- Ing. Nini Stefan Erwin
- Ing. Nischelwitzer Andreas Christian
- Ing. Nittmann Martin Josef
- Ing. Noichl Wolfgang
- Ing. Noori Khadjavi Jahangir
- Ing. Norbert Lilg e.U. Totalbau- unternehmen
- Ing. Norbert Rieser GesmbH & Co KG
- Ing. Norbert Wondrak GmbH
- Ing. Nothdurfter Christoph
- Ing. Novak Joachim
- Ing. Novi Andreas Walter
- Ing. Novotny Felix
- Ing. Novy Stefan
- Ing. Nowotny Kurt
- Ing. Nuhsbaumer Florian
- Ing. Nöckl Bernhard
- Ing. Nöhrer Werner
- Ing. Oberhauser Jürgen
- Ing. Oberhauser Mathias
- Ing. Oberhoffner Wolfgang
- Ing. Oberle Alexander
- Ing. Obernberger Stefan Günter
- Ing. Oberreiner Stefan Wilfried
- Ing. Oberrisser Klaus
- Ing. Oblak Christoph
- Ing. Ochsenhofer Karl
- Ing. Odziomkova Kristina
- Ing. Oegger Wolfgang
- Ing. Offner Stefan
- Ing. Offner Wilfried
- Ing. Ofner Werner Peter
- Ing. Ogris Walter
- Ing. Oliver Pertl Projektentwicklung & Immobilien
- Ing. Olivia Drexler Planungs- und Baustellenkoordination GmbH
- Ing. Ondracek Heinz Franz
- Ing. Oppel-Straka Romana
- Ing. Oppitz Klemens
- Ing. Ornig Sarina
- Ing. Orsolic Antun
- Ing. Ortbauer Herbert
- Ing. Ortner Benedikt Sebastian
- Ing. Ortner Ludwig
- Ing. Ortner Markus Heinz
- Ing. Oskar Kauffert Handel e.U.
- Ing. Osterauer Martin
- Ing. Osterkorn Tina
- Ing. Oswald Hartlieb
- Ing. Oswald Jenewein Wohnbaugesellschaft m.b.H.
- Ing. Oswald Martin
- Ing. Othmar Möser Bühnen- u. Steuerungstechnik e. U.
- Ing. Othmar Möser Elektroanlagenbau
- Ing. Ott Hilmar
- Ing. Ott Iris
- Ing. Ottmann Walter
- Ing. Otto Berger e.U.
- Ing. Otto DEMEL GmbH
- Ing. Otto Walter
- Ing. P. Weigel KEG
- Ing. Paar Leonhard
- Ing. Pabinger Matthias
- Ing. Pacher Gernot
- Ing. Pacher Siegfried
- Ing. Paczynski Krzysztof Tomasz
- Ing. Paheiner Markus
- Ing. Pahl Sarah Martina
- Ing. Pahr Noel
- Ing. Palatin Stefan
- Ing. Pall Helmut
- Ing. Palzenberger Markus
- Ing. Pammer Alfred
- Ing. Pamminger-Gruber Julius
- Ing. Pangratz Stefan
- Ing. Pantucek Anton