What is MDH?



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Good exterior design and using higher-quality construction techniques and materials are important factors.

This ensures a successful medium-density housing development that maintains value and aesthetic quality. Specify construction materials that weather well, require minimal maintenance and can withstand the long-term effects of the prevailing weather and environmental conditions.

Weathertight design

A lack of weathertightness is typically a problem associated with stand-alone or low-rise residential construction. However, weathertightness issues also affect MDH construction.

All MDH developments need to be designed to manage water that may occasionally penetrate the exterior cladding. This moisture must be removed from the assembly via gravity drainage and drying.

Factors that influence weathertightness risk in MDH include:

  • wind forces and pressures generated on the building façade
  • height of the building – greater height increases exposure, wind pressures and the water catchment area and run-off
  • the width of the eaves – smaller eaves mean less shelter and greater risk
  • detailing, complexity and the method of construction of junctions and intersections
  • the presence of decks and balconies
  • complexity of the building and its detailing and the quality of the weatherskin
  • surrounding developments – existing and future
  • type of cladding.

The most common points of water entry found in leaky buildings are:

  • joints between windows and the wall cladding or structure
  • cladding joints or junctions
  • parapets and balcony walls that have not been properly flashed
  • cladding failure, such as cracks in flush-stopped joints or shrinkage cracking in stucco due to a lack of movement in control joints in both cladding types.

Other potentially problematic areas that can be addressed with good design and detailing include penetrations (fixing, service or structural) through the cladding and waterproof decks.

External fixtures

When locating external fixtures, consider the aesthetic impact they will have on occupants and the character of the dwelling and ensure they are as unobtrusive as possible. Typical examples are television aerials and satellite dishes, solar panels, plumbing vents, pipework and water tanks, air-conditioning units, gas bottles, rainwater tanks and other exterior appliances.

Where possible, design each housing unit to accommodate these fixtures in advance, whether they are installed or not. For example, provide each housing unit with an unobtrusive base for a ground-level air-conditioning unit. Occupants can then install and update the air-conditioning as desired without affecting the character of the dwelling.

External fixtures can be removed from line of sight by relocating them into the roof space (where one exists) or concealing them with parts of the structure, such as behind parapet walls. Where this isn’t possible, consider purpose-built exterior structures to screen or disguise larger unsightly fixtures or obscure them from the street and neighbouring developments. Take care not to obscure desirable views and daylight admission.

Façades and roofs

The design of MDH façades and roofs should complement the character of the area and add to the appeal of the immediate surroundings.

Integrate balconies, terraces, railings, awnings and related features into the fabric and arrangement of the overall façade. Make the most of any desirable views and features of the development while ensuring occupants’ privacy from adjacent dwellings and the street.

Variation in form can be achieved by using different balcony and terrace designs in different parts of each dwelling or areas of the development. For example, recessing balconies and terraces by different amounts adds interest and variation to the façade while maintaining a degree of privacy. Consider integrating balustrades and barriers that vary between solid, semi-opaque and translucent.

Balconies and terraces should not allow run-off and water spillage down to any units, balconies or shared spaces below. Channel run-off into the stormwater system. Do not drain it towards open external edges, as water can leave unsightly stains, compromise weathertightness and create maintenance problems. At the same time, avoid long runs of unsightly downpipes on visible parts of the building.