Katrine's home is easy to find and by bus only 10min by bus from the center.
It was a very nice place to come to in the evening after finishing sightseeing and to relax our aching feet.
Even though the appartment is quite small there is room for 5 persons to sleep.
Since there is a fully equipped kitchen available we could cook in the evenings and save some money to spend for souvenirs :)
Katrine herself was very helpful and answering right away when we had some questions. Check-In and Check-Out were easy thanks to her clear instructions.
I can only recommend a stay at her place while visiting Oslo.