From Paris, take the A6 motorway to Porte d'Italie or Porte d'Orléans, then the A10 motorway towards Chartres/Nantes, exit No. 10 (Saint-Arnoult / Dourdan).
Turn right towards Rochefort en Yvelines (or left if you come from the provinces), at the roundabout, turn right and enter Rochefort, you are in rue Guy Le Rouge, I am at No. 73 on the right just before the stop sign.