Retiree Mr Lopuszynski, 64, said he had recently seen a vast increase in the number of "two-storey, 99 per cent concrete covered blocks, with no green, no trees, just concrete" being built in Oak Flats and surrounding suburbs.

He likened these types of homogenised builds - sometimes stand-alone homes and sometimes duplexes - to "prison blocks", and said they are inappropriate for families and seniors, and aren't consistent with the character of older suburbs.

"They're blocking views and fronting people's backyards with bland white walls with windows to look into your yard, casting shadows throughout the day," he said.

"Every time I look at these very basic builds I think of prison blocks. These types of builds are not appropriate in our suburb, and not attractive at all.

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"They are destroying our green suburb. They belong in new two-storey estates, or suburbs where higher density already existed, not here."

Mr Lopuszynski's post in the 'Our Oak Flats' online community group struck a chord with many.

"Not being a snob, but Oak Flats (is) turning into townhouse city," one resident posted.

"Money talks," wrote another. "People don't care for suburbs when they don't live there and are only developing to make money."

However, the shift to houses which take up more of the block, or cram in more dwellings in space previously occupied by single homes is not restricted to Oak Flats.

A code that makes it easier for landowners and developers to build terraces and other medium-density homes came into full effect statewide in July, despite widespread protest from councils including Shellharbour and Wollongong.

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The Low Rise Housing Diversity Code - formerly the Low Rise Medium Density Housing Code - is intended to accelerate the approval process for so-called missing "middle homes" such as terraces and manor houses, in which a single building contains three to four dwellings.

According to the state government, the code allows "well-designed dual occupancies, manor houses and terraces (up to two storeys) to be carried out under a fast track complying development approval".

Through the use of "complying development" rules, approval can be issued within 20 days - and with no consultation with surrounding neighbours - if the proposal complies with all the relevant requirements in the State Environmental Planning Policy.

Likewise, the state government's rules around complying or exempt development for single homes means private certifiers can sign off on buildings that are straightforward and tick the right boxes to be approved, without needing council approval.

Mr Lopuszynski said he feared a further loss of character for some suburbs, citing Shellharbour Village as an example of where this had already occurred.

"If it continues, the higher density will lead to not a community, but a ghetto-type situation, or a situation where everyone's living on top of everyone else... Just grey boxes upon grey boxes.

"A lot of people will say, 'you're a Baby Boomer, you're trying to preserve your lifestyle. We can't buy that land. It's easy for you to say'. But I want families to come in and have an environment, or live in a block where they've got green, the kids can run around and kick a ball, and can go out into the street without being run over.

"Just keep it lower-scale; that's what we're after."

Shellharbour Mayor Marianne Saliba said council had designed town centre plans for each of the local areas to try and ensure they have their own identity.

"This is not a response to the current medium-density (regulations)... This was the plan before the state government allowed this to happen.

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"Many of the older lots in a suburb like Oak Flats are quite large, and because of that, developers have been buying them up, and then putting in four, six or eight apartments, townhouses.

"I've noticed this not just in Oak Flats, but in some parts of Warilla and other parts of our city.

"Unfortunately, many of these are complying developments, and so they go to a private certifier and we have nothing to do with it. That's always a struggle for us."

However, Cr Saliba acknowledged the region was a sought-after location to live, and in terms of housing, it was "striking a balance between our demands and aspirations".

Shellharbour councillor Peter Moran said the council's ability to limit this type of development in any of its suburbs had been diminished over the years.

"The problem is various state governments have looked at what is an appropriate planning system to be be implemented in Balmain, Marrickville or other inner-Sydney areas, and have just plonked that over the whole of the state," he said.

He said Shellharbour City Council had been "ahead of the game", and already either provided or are planning to rezone sufficient land to account for any population growth in Shellharbour over the next 20 years.

"We don't need this densification of our suburbs because council has provided for different housing types and a greater rezoning of land," he said.

"Often the development industry will say, 'you've got to provide various types of housing for different people, according to their needs'.

"That's entirely appropriate, and they also say, 'if you don't build, where are people's children going to live?' And that's fair enough too, but we've done that.

"We've done it, and we shouldn't be subjected to the same rules as councils that haven't done that."

However, some view medium-density housing, both in existing suburbs and newer ones, as key to boosting affordability.

Housing Industry Association executive director David Bare lives in the Illawarra.

"It's one of the best ways to deal with affordability on the one hand, particularly given where land prices have gone," he said.

"And having higher density is an important element of our future housing stock. Everyone can't be on a half-acre block."

Mr Bare said while some residents viewed even small amounts of medium density as "the thin end of the wedge for their area, people do need more affordable options these days".

"It's those entering the suburbs and wanting to get a foothold in home ownership that need these types of offerings.

"And in this day and age, not everyone wants a backyard... For people who don't want to be maintaining a block of land and other aspects, they're also easier to maintain."

Mr Bare said the Low Rise Housing Diversity Code requires that a development must meet all of the development standards in the code, but it must also meet the design criteria of the accompanying design guide for complying development.

He said this includes a section on "local character and context".

"(The guide) aims to ensure a consistent approach to the design, layout, landscaping, private open space, light, natural ventilation and privacy of medium density development," he said.

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