Construction waste in the Havelock North Best Home

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According to REBRI, up to 50% of landfill comes from construction and demolition waste.  Given that New Zealand has a significant recycling and commercial composting industry, construction and demolition wastes should be viewed as a resource that needs careful management. 

The Havelock North Best Home™, built by Horvath Homes for Hastings District Council, provides an inspirational example of how to reduce construction waste to a minimum.

 

How did they do it?

Horvath Homes focused on both reducing the amount of waste produced and diverting as much waste as possible from landfill.  They had economics in mind; the cost of skip hire and landfill disposal of construction waste is substantial.

The construction manager, Hugh Campbell, was in charge of minimising waste.  He prepared a short waste management plan (less than 1 page) before construction commenced.  This identified the major sources of construction waste and where they could be recycled.  He also briefed all subcontractors on the waste management requirements.  

A key difference in the management of construction waste for the Best Home building site was the absence of a skip for wastes to landfill.  In fact the only bin on site was for timber; all other wastes were piled up and removed quickly when produced.  This meant that the site remained tidy, and the temptation to stick recyclables in the bin destined for landfill was eliminated.

Off-cuts and other construction waste were sorted and weighed on site.  Where possible, materials were re-used or recycled, and only the remaining materials were sent to the landfill. 

Many materials suppliers took responsibility for the wastes generated by their materials.  For example:

  • Timber off-cuts were taken back by PlaceMakers, used for noggins, jack studs and blocking, and any remaining timber waste was used as fuel in the nearby Whirinaki Power Station
  • Paint containers were taken back by the supplier for recycling, and waste water from paintbrushes was cleaned in a paint cleaning system.
  • Plumbing and drainage offcuts were taken by the supplier.
  • Polystyrene offcuts from the cladding were taken back by the supplier who returned them to the manufacturer for recycling.

Local recycling companies recycled cardboard, concrete, Linea weatherboards, plasterboard offcuts and plastics, ensuring maximum diversion of wastes .

In addition Horvath Homes reused some offcuts (e.g. building wrap, polythene sheeting) on other houses under construction.

 

The results

The Havelock North Best Home™ has a total floor area of 186.68m2.  In total, 15.15kg/m2 of floor area (2829.15kg) of waste was generated from the house’s construction.  Of this, 95% (2696.15kg) of waste materials was diverted from landfill. 

It is interesting to compare this to standard build houses, in this case a study by Christchurch City Council of the construction waste produced in “normal” homes being built around the city (pre-earthquakes).

 

Builder

Waste by floor area kg/m2

Waste diverted from landfill

Waste to landfill kg/m2

Waste management method

GJ Gardner

17

70%

5

All waste in skips (2.5 x 7.5m3 skips used)

Jennian Homes

18

75.5%

5

 

All waste in skips (4 x 7.5m3 skips used)

Mike Greer Homes

22

54%

10

All waste in skips (4.5 x 7.5m3 skips used)

Orange Homes

23

60%

9

All waste in skips (3 x 7.5m3 skips used)

Stonewood Homes

21

80%

4

All waste in skips (3 x 9m3 skips used)

David Reid Homes

19

84%

3

All waste in skips (4 x 7m3 skips used)

Benchmark Homes

25

82%

4

All waste in skips (3 x 7.5m3 skips & 2 x 3m3 skips used)

Golden Homes (steel framed)

12

76%

3

All waste in skips (2 x 7m3 skips used)

Havelock North Best Home

15

95%

0.7

 Sorted on site with bin only for timber 

 

How did Horvath Homes get such a good result?

A critical factor in Horvath Home’s success was the strong commitment of the construction manager - and all the tradespeople working on the site - to sorting waste as it was generated, and making use of every possible recycling option.  Clear briefings on the waste management objectives, the frequent on-site presence of the site manager, and good project management (in which waste reduction and recycling was an integral part of the project) explain why the waste management practices were so good.

Equally important was the absence of a general waste bin on the site.  Waste to be sent to landfill had to be consciously sorted into a pile.  This is a totally different approach to the normal waste management on a construction site where the large landfill skip is provided, making it easy - and tempting - to dispose of waste to landfill. 

The availability of recycling options for plasterboard, concrete waste and timber were critical to achieving such a good result - these three wastes represented nearly 79% of the total waste generation.   Also impressive was the product stewardship approach of material suppliers which made a big contribution in terms of weight of waste recycled. 

When the types of waste are analysed, two further points stand out.  One is the absence of hazardous waste in the Havelock North Best Home™, a positive result of careful selection of low VOC and non-toxic materials and products.     

The second is that errors and rework generate substantial extra waste, even in this well-project managed house.  Over 58% of the waste produced was concrete/masonry.  This was reflected an error in the installation of a concrete thermal wall in the house, which then had to be completely reworked - creating an extra 900kg waste (31.8% of total waste generated). 

Horvath Homes achieved excellent results with their approach to construction waste management in the Havelock North Best Home™.  Clearly a combination of good waste reduction practices combined with sorting and diversion from landfill can result not only in less waste to landfill but also in construction savings. 

 

 


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Waste sorting in the Best Home