What is MDH?



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In order to communicate effectively about medium-density housing, it’s important to understand what the term means.

Unfortunately, there is no standard definition of MDH, with several differing and sometimes contradictory definitions in common use in New Zealand and overseas.

Many of these definitions include seemingly arbitrary limits for site size, building height, number of units per site or number of dwellings per hectare. Some definitions mention the type of house, while others focus on the density of dwellings over a specific site size or land allocation.

The Ministry for the Environment's 2012 definition rates many of the different aspects of MDH included in the other definitions:

Medium-density housing means comprehensive developments including four or more dwellings with an average density of less than 350 m² per unit. It can include stand-alone dwellings, semi-detached (or duplex) dwellings, terraced housing or apartments within a building of four storeys or less. These can be located on either single or aggregated sites, or as part of larger master-planned developments.

While this describes MDH relatively well, it places arbitrary limits on the number of dwellings, site size and building height. Each of these is contradicted by other definitions used in New Zealand, meaning that this definition is unlikely to be universally accepted.

To provide the industry with a simple description that works with existing definitions and enables everyone working in the field to use common terminology, BRANZ has defined MDH as:

Multi-unit dwellings (up to 6 storeys)

This definition brings together the disparate terminology currently in use and encompasses all the types of buildings that are commonly considered MDH in New Zealand. It is also flexible enough to encompass new classes of building as they emerge.

The density scale

On the housing-density scale, MDH sits between low-density housing (LDH) and high-density housing (HDH).

In New Zealand, LDH includes stand-alone dwellings, generally 1–2 storeys, on an individual section where the size is greater than 400 m2. HDH includes apartment buildings greater than 6 storeys, with individual dwelling unit sizes ranging from studio apartments to 3–4-bedroom apartments.

The BRANZ MDH definition above excludes stand-alone buildings, including those erected on a larger site that has been subdivided, and but includes apartment buildings up to 6 storeys high.