How many houses can you fit in 430 hectares?

I blogged on 21 May:

MBIE sent this brochure out yesterday inviting stakeholders to a programme launch to develop on Crown land in Auckland. This may be giving away a Budget announcement. It even details how they have identified 430 hectares of Crown land in residential zoned areas in Auckland.

If you assume 13 houses per hectare (average in Australia) that’s enough land for around 5,600 new houses.

The 13 houses per hectare was based on the average size in Australia. But I did not take into account new houses are likely to apartments or townhouses. An architect e-mails in:

David- I’ve been thinking about your post of 21st May ‘Govt to make up to 430 hectares of crown land available for Auckland housing’ and I think your vastly underestimation how many houses/ units could be built if you did them as townhouses (or apartments)- my thought would be townhouses would be the best bang for your buck. I am an Architect in Christchurch who does a lot of brownfield townhouse and apartment development (over 165 units completed over the last 12 year and many coming), attached is analysis using real examples based roughly on a 1/4 acre section (1012 sqm/ 50.24 x 20.12m wide) then added another 201sqm to allow for a 10m wide road (road might be 20m but it would service a site each side. I have assumed:

  1. no parks/ commercial function (e.g.: dairies)/ community function was added they would take maybe 5-7% space (i.e.: reduce units by about 5%) as its brownfield sites such features might be nearby already
  2. if stormwater retention, sewer plant needed more space again needed
  3. doesn’t allow for more density due to bigger site=less boundary restrictions (could add maybe 5-10%)
  4. All townhouses are 2 storey with approximately 30-35 sqm of outdoor living and service space (washing line/ bin space). All would comply with Auckland/ Christchurch city council minimum unit size rules

If you did a development of 

  • 2 bedroom townhouses with single garage you could get a density of round 50-65 units per hectare, over 430 hectares that’s about 21-28,000 units
  • 3 bedroom townhouses with single garage you could get a density of round 40-50 units per hectare, over 430 hectares that’s about 17-21,000 units
  • 3 bedroom townhouses with double garage you could get a density of round 35-40 units per hectare, over 430 hectares that’s about 15-17,000 units

If you went apartment style (these figures are far more approximate)

  • 1- 2 bedroom units 2 storey with 1 car park you could get a density of round 70-85 units per hectare, over 430 hectares that’s about 30-35,000 units!
  • Small 2 bedroom unit, 4 storey small units, small deck, 1 carpark uncovered you could get a density of round 118 units per hectare, over 430 hectares that’s about 50,000 units! This figure is so crazy high I must have made an error, but I cant see it (example has 32 units on 2254 sqm=14.3 units / quarter acre)

So that 430 hectares could end up providing a lot of accommodation.

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