Housing Survey DataSet Component/Element Distribution Costs

This analysis  is based on 274,000 rows of data regarding social housing survey of interior and exterior inspections. It has been filtered for building fabric, services and joinery have been excluded at the beginning.

It is a bit of a haphazard blog. I used Knime to filter out the data and slowly filtered building data to higher granularity.

The intention was to show different types of graphs representing the same data to explore variety of expressions, but as the data was refined further the scatter plots seem to show clearly which elements have the higher value, and delving into the data shows which are high and low maintenance. Also labeling of data helped clarify the information.

Total costs of all elements in the first two tables is  $53,640,910.

The largest component by far is external windows at $15,842,123

Followed by external walls, internal walls, floors and interior doors all about half of the amount of the external windows. (Note- survey was non-invasive so floor structure was not necessarily noted if it was covered by carpet or vinyl).

Windows are by far the highest cost item on the element scale, followed equally by external walls, internal walls and their finishes, floors/floor finishes (note- these are mainly floor finishes) and interior doors. All of these later components are about half the value of the windows

Roofs, which are an insignificant amount of the total sum at $714,000 or 1.3% of total sum, is an important item for Maintenance, as a failure in the roof could cause water damage that can affect the electrical system, internal ceiling, wall and floor fabrics and furniture, so making sure roofs are maintained should be prioritised.

External windows, if aluminum usually require minimal maintenance unless neoprene seals are falling out or if windows have been installed incorrectly in which case they will need sealing at regular intervals.

If the windows are timber there is a higher maintenance requirement. This in turn , for high rise buildings, may require scaffolding to access. So if window replacements are planned then they should be planned for higher levels in buildings (more expensive in short term/capital cost, but lower maintenance costs in the long run).

External doors are generally accessible so maintenance is not an issue.

External cladding, split into 2 types, durable, concrete, even cement-fibre boards and  not so durable timber, that rots on south and east faces if not well maintained. Also painting requires scaffolding. So more durable finishes, although they have high upfront cost.

Building Value Dataset further split down into more durable components (metal doors/windows and less durable such as timber doors/windows that require painting and patching to maintain their condition. Also note Door hardware is a high cost of these elements.

This dataset is for a city in New Zealand. Nowhere in New Zealand is more than 90 km from the sea so there is a high salt environment and NZ has a high UV content to the sunlight, which has an impact on external paints and plastic elements unless they have UV inhibitors. Steel can corrode if not protected well from salt corrosion.

Paints will break down faster due to high salt in the atmosphere and high UV. So washing them regularly will have an impact on  extending their life. External plastic gutters  & waterproof roof membranes have plasticisers to give them flexibility, the high UV will cause the plasticisers to off-gas causing these items to become brittle , and if ladders are leaned against plastic gutters them they can crack/break quite easily.

Finding the most appropriate way to manage your assets to maintain a defined quality standard either by proactive maintenance or reactive maintenance is an important balancing act. A leaking roof can have a much greater effect than a leaking window, but the quality of the interior finishes, as a perception for the tenant is also important. If a property looks cared for, then it is generally cared for, but if it looks neglected then you get a version of  ‘tragedy of the commons‘ where everyone else neglects the property also, accelerating its condition decline.


When services and grounds are added to the mix then the total sum goes up by another 50%. Electrical services are the highest addition followed by plumbing, but since the plumbing are only fixtures and not pipework also the costs for plumbing services could be comparable to electrical if the cabling and pipework was added to the costs.
Donut chart
Force Diagram


When furniture, lifts, stairs and security are added, total sum is 94M. Furniture is then 2nd to windows in value.



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