Designing and building affordable houses

This Issue This is a part of the Affordability feature

By - , Build 106

The affordability debate often focuses on policy and the demand-end responses, but for the building industry, the more important questions may be what should affordable houses be like, and how can we lower the building cost?

Figure 1: A house design should efficiently use all the space. When the circulation (shaded area above) is deducted from the central living/dining area, the space left struggles to serve a useful purpose and is, in essence, wasted.

Google ‘affordable housing’ and you will get thousands of hits, each with a different view of why affordability is such an issue – from the tax regime to language barriers, public transport to human nature. The drivers of affordability are complex and interdependent, and there is no single silver bullet for a fix. Recent BRANZ research reveals land prices as the arch-villain in the current affordability crisis, with section costs climbing at about five times the rate of wages (see pages 47–48). The research also shows growth in house building costs outstripping wages by about two to one.

Although affordability affects all housing, it is critical in low-cost homes, where the benchmark is meeting basic needs rather than catering for personal preferences.

Information needed on building affordable houses

There is an Affordable Housing Bill before Parliament and a flood of debate about policy and social solutions, but there is a lack of information about how those actually producing buildings should meet the challenge of affordable housing. Apart from the Building Act, which controls technical standards of construction, there are few documented hard facts that clarify bottom-line standards for low-cost housing.

The construction industry is thus challenged as much by ‘what should affordable housing be?’ as by ‘how can we build it more economically?’ This lack of clarity was highlighted in BRANZ’s latest Building Research Industry Needs Survey, which ranked affordability high on the research priority list.

Keeping up with shifting baselines

In the housing industry, as well as many other areas, standards and expectations tend to rise incrementally over time. These ‘shifting baselines’ affect our frame of reference for almost everything from building regulations and client expectations, to what is considered ‘adequate’ and ‘affordable’ housing. Think back to the 1970s, before thermal insulation became mandatory, or the 1940s when showers had yet to appear and safes prevailed over fridges. Go back a full 100 years and state housing featured ‘the latest conveniences, including hot water…’

Optimistically, Housing New Zealand Corporation maintains that quality improvements ‘should not affect affordability’. Not only does this seem improbable, but history tells a different story. According to Ben Schrader’s We call it home: a history of state housing in NZ, the hot water aimed at improving early state houses contributed to ‘pricing the dwellings beyond the means of the average worker…’.

The trend still continues – Statistics New Zealand reports that, from the early 1990s, the average house size has grown about 40% while ‘occupancy rates have become smaller’. Small wonder houses are less affordable – we are building larger houses to accommodate fewer people. This prompts the question, ‘do we sometimes raise standards too high, and do we then have the courage to lower some?’ As one builder observed of the post-leaky-building environment: ‘We’re building submarines now, not houses!’

What is affordable housing?

With such moving goalposts, it is a constant struggle to find the right balance between amenity and affordability, and we may well ask what is a valid baseline for affordable housing. Unearthing one proves no simple quest.

Standards New Zealand gets no closer than NZS 4102: 1996 Safer house design (guidelines to reduce injury at home), while the Salvation Army’s substantial advocacy document Rebuilding the kiwi dream: a proposal for affordable housing in NZ is silent on actual housing standards. Some councils do set minimum apartment sizes via their District Plans, and Statistics New Zealand’s Housing statistics strategy at least discusses ‘The six dimensions of housing adequacy’ (from The Universal Declaration of Human Rights – affordability, suitability, habitability, tenure security, freedom from discrimination, and freedom from overcrowding). These are admirable aims, but fuzzy, and when the same strategy explores ‘suitability’ in greater detail, it remains stuck with qualitative terms like ‘appropriate’ and ‘flexible’.

Generic design briefs may offer some specifics

With its commendable Design guidelines – Architecture, Housing New Zealand Corporation seems at first committed to the same qualitative vocabulary (‘appropriate space’, ‘flexible use’ etc.), but they also produce ‘generic brief’ documents that present a wealth of specifics from doorway widths to water tank capacity. It is debatable whether benchtops really must be a minimum of 600 mm deep, but at least we can now hold that debate.

Perhaps the generic brief documents are the closest we currently have to an ‘affordable housing’ baseline. Even then, we should ask how well-founded the documents are and whether Housing New Zealand’s requirements are valid for other modes of low-cost housing, such as seasonal workers’ accommodation or entry-level homes.

It is clear that research is overdue in this field, where there is a desperate need for authoritative data as a basis on which the industry can tackle the problem.

Designing out waste

Even if documents like the generic brief do set design and finishing standards, the challenge of meeting them economically still looms large. One way to pull down costs is to reduce waste. It is tempting to point the finger at builders, because we naturally think of waste as leftovers – off-cuts and so on. But there is a lot more to it than simply reducing surplus materials.

Figure 1: A house design should efficiently use all the space. When the circulation (shaded area above) is deducted from the central living/dining area, the space left struggles to serve a useful purpose and is, in essence, wasted.

Dictionaries help by pointing to the broader idea of waste as things ‘not serving a useful purpose’. While builders play a key role, and there is always scope for improved construction efficiency, they are just one link in the building procurement chain. Singling them out neglects other creators of waste, such as designers.

Ask people in the industry about ‘designing out waste’ and most will suggest setting wall dimensions to suit sheet sizes. Valid as this is, it is just the tip of the iceberg. As well as affecting the plan and appearance of a building, design influences most other aspects from expectations to excavations, and from concepts to concrete work. Each of these is a potential source of waste. Designing out anything ‘not serving a useful purpose’ can help affordability.

At the macro scale, take space planning. The poorly resolved plan in Figure 1 includes floor area ‘not serving a useful purpose’: the already modest living/dining area proves almost unusable when circulation is considered. The waste is both the cost of the unproductive space and the compromises to the very functioning of the home.

On a smaller scale are strip footings. The sizes in NZS 3604: 1999 Timber framed buildings are often expanded because diggers don’t have small enough buckets. It is not just concrete that is wasted – there is the extra excavation, soil cartage and tipping, and longer construction programmes.

There is a raft of other potential savings, such as adjusting downpipe locations to minimise drain lengths, or following the thrifty lead of group builders, who have got construction costs off pat. It is no coincidence that they prefer hipped roofs and 140 × 45 mm floor joists. Or designers could buck the trend and rediscover pendant lights which need fewer fittings, provide better light throw and don’t create so many holes in the thermal envelope.

Affordability with sustainability

What is good for affordability is often good for sustainability too. If a building is less wasteful – whether by efficient planning or eliminating redundant structure, by energy conservation or minimising construction waste – then the environment is helped as well as the cost.

However, we should not ignore features that might increase initial costs but yield long-term benefits, such as solar water heating, extra thermal insulation or some low-maintenance components. For example, Housing New Zealand predicts homes of the future will have ‘lower ongoing maintenance and lifecycle costs’. To justify the cost of such features, we need to see beyond our fixation with initial capital outlay and factor in improved lifecycle costing. For affordable housing especially, subsidised finance may be essential to achieve the inclusion of such desirable features.

Multi-faceted approach needed

Escalating building costs are a major issue in the widening gap between house prices and people’s ability to pay for them. This disparity is creating problems in all housing sectors but is most critical in low-cost accommodation where meeting even basic needs is sometimes too expensive.

In the face of ever-rising expectations, of unclear minimum housing standards and of pressures to improve affordability, several challenges confront the construction industry. To meet these challenges, the industry needs to adopt a multi-faceted approach, founding its actions on authoritative and relevant research, and reviewing standards and work practices with openness and innovation.

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Figure 1: A house design should efficiently use all the space. When the circulation (shaded area above) is deducted from the central living/dining area, the space left struggles to serve a useful purpose and is, in essence, wasted.