Question pretext
The age of the building is an important factor in any assessment of housing condition generally.
Minor repairs, renovation or improvement of the building does not in general change the year of construction.
Interviewer instructions
For those households living in incomplete buildings, take the year of occupancy as the year when built, whilst for reconditioned (renovated) dwelling units, the year when major reconditioning (or renovations) were done. Note that the household may genuinely not know when the dwelling was built, especially if a member of the household does not own it, ask them to estimate based on other events that may have taken place around that time.