Seomraí: the international evidence

International evidence shows how removing barriers to building small homes boosts housing supply

Yesterday, the government announced that planning rules for seomraí–or ’granny flats’, as they are sometimes called– will be relaxed. This follows from a Programme for Government commitment to “examine” the idea of allowing detached dwellings to be built in gardens. It also follows from Progress Ireland’s own work on the topic which can be found here.

This announcement is excellent news and a rare win-win. It is good news for the thousands of young people crammed into shared houses or their parents' spare bedroom. It is excellent news for the growing number of older people looking for rightsizing options in their communities. It is good news for families with a disabled loved one seeking to balance independence with proximity to family support. And it is potentially good news for homeowners who may wish to supplement their income by renting out a seomra once their children or loved one has moved on.

While no single idea is a silver-bullet, the idea has shown tremendous potential abroad.

As the government crafts its seomraí policy, it would do well to look at the story of the policy’s success in other jurisdictions. That success follows a similar pattern everywhere: to deliver more housing options, reduce barriers to building.

The government has set out on the right foot by suggesting that seomraí fall under the exempted regulations, removing the requirement for planning permission. But adding unnecessary requirements into the exemption such as owner-occupancy or parking will damage the potential of the policy to deliver for those who need it most. Other jurisdictions have found this out the hard way, through trial and error. This article will go through the international evidence about how removing these kinds of barriers ultimately helped boost the supply of homes.

Before that, a point on terminology. What we call seomraí here are called ‘accessory dwelling units’ or ADUs in the United States. In Canada, when detached, they are called laneway homes; when attached, they are called secondary suites. In Australia and New Zealand, they are called granny flats.

California

Up first is California. They have been at this for a while. Their first foray with ADUs was in 1982 when the California legislature passed SB 1160, a bill designed to encourage local jurisdiction to allow ADUs on all single-family plots. What unfolded in the intervening thirty plus years was a story of state level regulations conflicting with local authorities' rules resulting in a cat and mouse game of patchwork regulations.

This changed between 2016 and 2023, when a flurry of no fewer than eleven ADU bills made their way through the California state capitol. This period shows what is possible when the regulations are gotten right. What the bills of 2016-2023 together achieved was a building boom.

In those six years, California’s ADU approvals went up by 15,334 per cent. As of 2022, 19 per cent of all housing units produced in California – or nearly one in five homes – was an ADU.

Before 2016, those that wanted to build an ADU confronted onerous permitting processes, owner-occupancy requirements, and unworkable minimum parking rules. Once these rules were lifted, supply increased dramatically.

A similar story can be told in Los Angeles. In 2022, 1 in 3 homes permitted in Los Angeles was an ADU. At least 26,862 ADUs have been permitted in LA alone since legalisation. But it wasn’t always like that.

The regulations set by the city of Los Angeles prevented many ADUs from being built. In 2016, only 80 ADU permits were granted in LA. By 2022, that figure increased by 8,850% to 7,160. The massive leap shows the potential of ADUs, if the regulations is gotten right.

Portland, Oregon

Next up is Portland which has been a world leader on ADUs for decades, building more ADUs per capita than Los Angeles. But their success was hard-won. It took decades of patient advocacy, from green builders, advocates for ageing in place, and elected and city officials to get them to this point.

ADUs have been permitted in Portland since the early 1980s. Senate bill 100, passed in 1973, created urban growth boundaries and set concrete house building goals. Importantly, city planners could not discriminate on housing type in meeting these targets.

These early reforms got a lot right, for instance they did not straddle residents with minimum parking space requirements. By 1981, homeowners in some neighbourhoods could convert part of their home into ADUs. But uptake was still low.

In 1998 city officials updated the regulations governing ADUs. Where before ADUs were only permitted for homes older than five years old, the new reforms allowed ADUs to be built along with the primary dwelling. Prior to the 1998 reforms, all ADUs were subject to owner-occupancy requirements. The new suite of reforms meant that homeowners no longer had to obtain express approval from their neighbours to build on their own plot, a move that proved controversial at the time.

In 2004, the city rolled back restrictions on garage conversions, reduced setback requirements, and eased standards to do with roof pitch, windows, trim, and exterior finish.

Despite the efforts of city officials, uptake was relatively slow with an average of 30 ADUs being permitted per year between 2000-2009 in a city of about 570,000.

After 2010, ADU construction shot up. The story of how that happened, like that of California, was one of removing unnecessary barriers to building.

The 2010 reform–resolution 36766–suspended a steep payment to the city called a system development fee. Designed to cover servicing costs, this fee was as high as 7,000 to 12,000 USD per unit. These fees were suspended again in 2012 and again in 2016. In 2018, the fees were permanently scrapped with the proviso that all ADU’s exempt from the system development fee not be used for short-term rental accommodation for the next 10 years.

That same year, minimum lot size and minimum ADU floor space requirements were relaxed.

These reforms saw ADU construction increase by an order of magnitude from 50 units/ year before 2010 to just over 500 in 2016-2018.

The reforms and outreach together triggered a boom in affordable housing. A 2019 report found that, in Portland, ADUs were on average less expensive per square foot than apartments. More often than not, this decrease in input costs resulted in lower rents: ADUs in Portland rent for less than the median rent of the area.

There are many lessons to take from Portland’s experience. But a central one is that putting unnecessary regulatory and financial barriers in place reduces supply.

Seattle, Washington

Seattle stands out as a leader in proactive schemes to support ADU construction. Regulatory changes combined with city-led outreach has increased their ADU permits by 253%. The scale of ADU production in Seattle was achieved by adopting regulations explicitly designed to encourage supply.

In 2015, Ed Murray, the Mayor of Seattle, set a goal of building 50,000 new homes in ten years. The Seattle Housing Affordability and Livability Agenda Advisory committee was established, and submitted recommendations to Mayor Murray. These recommendations included “removing specific code barriers that make it difficult to build ADUs and DADUs.” They recommended that minimum parking requirements and owner-occupancy restrictions be lifted. The committee further suggested that both attached and detached ADUs be allowed on single family units.

On the back of that recommendation, Seattle City Council passed CB 119544. The bill exempted ADUs from floor-area-ratio requirements and noted the need to incentivise, promote, and market ADUs.

After the recommendations of the committee were implemented, coming into effect on the 8th of August 2019.

The following year, ADU permits increased by 75%, despite the impact of the pandemic. Relative to the 2019 figures, ADU permits were up by 253% by 2022. For the first time in the city, ADU construction overtook single-family home construction.

In 2023, 983 ADUs were permitted in the city, 650 of which have been built.

Just as in Portland, this success was achieved not only on the back of robust legislative action but with the help of sustained support. In fact, Seattle stands out as the leader in proactive engagement on this score. The city provides support for homeowners to build via 10 pre-approved detached ADU designs, providing a quick and predictable system.

Vancouver, Canada

Vancouver has been incrementally increasing the scale of ADU construction arguably since the 19th century. Secondary suites were banned during the 1950s, in a move parallel to Ireland’s banning of bedsits. But they were brought back in the 1980s. Inspection fees were reduced in 1989. By the 1990s, it was estimated that 23 to 27 per cent of homes in the city had a suite. In 2004, the city council allowed for secondary suites in all residential zones. Between 2004 and 2006, various restrictions were eased but not totally eliminated. Laneway homes were permitted in single family zones in 2009. Since 2017, Laneway homes represent nearly half of the permits issued by the city in residentially zoned lots.

Overall, the policy has proved so successful that 35 per cent of all single-family homes in Vancouver have some form of seomraí (whether attached or detached).

According to senior planners in Vancouver, the laneway house program has been “incredibly successful.” Demand is so high in Vancouver that the city’s permitting system is “considerably backlogged.”

New South Wales, Australia

In 2009, the NSW government enacted the Affordable Rental Housing and State Environment Planning Policy (which expanded further in 2021). The 2009 rules allowed “secondary dwellings” to be built across much of the state. It removed parking requirements or the requirement for secondary dwellings to be attached. The change also made secondary dwellings effectively exempt from planning permission.

In the decade following the change, approval surged. Between 2006 and 2021, secondary dwellings amounted to 1.5 per cent of Sydney’s total housing growth, amounting to thousands of new homes approved annually.

Learning from international success

The government is right to propose exempting seomraí from planning permission. In other jurisdictions, slow and uncertain planning processes has delayed home delivery, often with serious consequences. International experience makes one thing clear: the urge to impose layers of restrictions on seomraí must be resisted. Where that temptation is avoided, the policy has a proven track record of success.

With this welcome announcement, Ireland has the chance to bypass the pitfalls of trial and error and move straight to delivering for those who need it most. But if seomraí are burdened with excessive requirements or barred from rental use, this will become another missed opportunity.