What insulation does an older rental house need?

The same as any rental: ceiling and underfloor insulation, wherever it can reasonably be installed, meeting the minimum level for the property's climate zone. The age of the house changes the work, not the rule. A villa built decades before insulation existed is not excused; it is exactly the housing the standard was written for.

The three usual situations

• Never insulated: it needs doing, unless a specific space genuinely cannot be accessed, in which case do what is practicable and document why the rest is not.
• Insulated years ago: check condition, not history. Bulk insulation compacts and gets disturbed; older products that met older rules can sit below today's minimums, especially in the coldest zone.
• Partially insulated: common after past subsidy schemes, ceiling done, subfloor forgotten. The standard covers both.

How to actually check

If there is safe access, look: a photo of the ceiling space with a tape measure in frame, and the same under the floor, answers most questions and doubles as evidence. If access is difficult, an insulation installer's assessment is inexpensive relative to what it settles. The current minimum R-values are maintained on tenancy.govt.nz; measure against those rather than against memory.

Old houses have one advantage

Retrofitting insulation in an accessible ceiling or subfloor is among the highest-value work in the whole standards regime: it cuts the required heater capacity, dries the house, and produces clean, simple evidence. For character stock, it is usually the first domino, insulate, then size the heating, then stop the draughts, in that order.