Straight up: we build on site. Every home we do is framed on your block by our trades. So you're reading a comparison written by someone with a barrow to push, and you should weigh it accordingly.
I'm writing it anyway because I get asked about transportables a lot and the honest answer isn't "don't". It's "it depends on your block, and here's how to tell."
The people who end up happy with a transportable generally had a flat, clear site with a straight run in from a sealed road, and a plan they were content to take close to as-drawn. The people who end up unhappy generally had slope, trees, a narrow street or strong opinions about the layout, and found all of that out after paying a deposit.
What a transportable actually is
A transportable, sometimes sold as a modular or prefabricated home, is built in a factory or a yard, usually in two or more modules, trucked to your block, and craned or rolled onto footings that were prepared before it arrived. Once it's down, a crew comes through and does the join: the modules get bolted together, the roof over the join gets closed in, the services get connected, and the internal finishing across the joint line gets made good.
That last part is where expectations and reality sometimes part company. Delivery day is a great photo. It is not handover. There's a stretch of work afterwards, and how long that stretch is depends on how much the supplier does versus how much they leave to a local builder.
This is the same territory as granny flat kits, and the money mechanics are near identical, so what a granny flat kit price actually covers is worth reading if you're comparing on price. The short version: the number on the website is for the box, and the box is not a home on your land.
The things that still happen on your block, either way
A transportable does not remove the site.
You still need an approval, either complying development or a DA, and the assessment doesn't care where the house was assembled. You still need a survey, engineering, and a soil classification, because whatever the house lands on has to be designed for your ground. You still need footings, piers or a slab, built on site, by someone. You still need power, water, sewer and stormwater connected, and stormwater still has to discharge somewhere legal. You still need a driveway, a crossover if there isn't one, and whatever else the consent conditions.
All of that is the same list as a site-built home, and it's the list that generates most of the cost variability on any new build in the Illawarra. If you want the detail, site costs on a new build goes through what a soil classification changes and where rock and fill hurt.
So the fair comparison isn't "transportable price versus site-built price". It's "transportable price plus the site works, plus the connection works, plus the finishing after delivery" versus "site-built price". Get both onto that basis before you compare anything.
Where the truck decides your floor plan
This is the constraint people don't see coming, and it's the most interesting difference between the two.
A transportable module has to travel by road. That means it has to fit under bridges, around roundabouts, and within the width a permit will allow, with a pilot vehicle if it's oversize. Everything about the house is downstream of that: each module ends up a long rectangle, and the plan gets composed out of long rectangles joined along their length.
You can do a lot with that. Plenty of good transportable plans exist and a long rectangle suits a north-facing block beautifully. What you can't easily do is a wide open living space that spans the joint line without a beam in the ceiling, a raked ceiling that carries across modules, or an unusual footprint that steps and wraps. If you've fallen for a plan with a big square great room in the middle, that's a site-built plan.
The joint line is also a real thing in the finished house. Good suppliers make it disappear. Cheaper ones leave you a line in the ceiling you'll notice for the next twenty years.
Access, which is the one that rules it out around here
To land a transportable you need a truck to physically get to your block, and a crane to reach where the house is going.
On a flat block on a wide street with nothing overhead, that's a morning's work. On a lot of Illawarra sites it's not possible at all: a steep drive, a tight corner in an older street, mature trees over the frontage, overhead powerlines, a narrow bridge on the only approach, or a rear lot where the house site sits well back from the road. Rear lots in particular are usually a hard no for transportables, for reasons I've gone through in building on a battle-axe block.
Slope is the other one. A transportable wants a level, prepared platform. On a falling block you're either cutting and retaining to make that platform, which can cost more than the ground floor of a site-built house, or you're on tall piers with steps and decks to make it liveable. A site-built home can step down the fall instead, which is often both cheaper and better — split-level home designs covers how that works.
Before you get attached to the idea, have someone drive the delivery route and stand on your block looking at where a crane would sit. That single afternoon answers most of the question.
Where a transportable genuinely wins
It'd be dishonest to write this as a hit piece, so here are the cases where I'd tell you to go for it.
The build happens undercover, which takes the weather out of the schedule. Our wet winters here can add weeks to a site-built job and they don't touch a factory. Once your approval and footings are done, the run to a finished house can be short.
Factory conditions also mean consistent, repeatable work on a plan the supplier has built many times. There's less to go wrong in a process someone has run fifty times than in a one-off.
And you're on the block for less time. Less mud, fewer deliveries down your street, less of your life spent with trades in the driveway. For a second dwelling on a property you're living in, or a build in a location you can't visit often, that's worth real money.
If your block is flat and clear, your access is good, and a standard plan suits you, a transportable is a sensible thing to buy.
Where site-built wins
The block, mostly.
A site-built home is designed around your land: the fall, the aspect, the trees, the view, the awkward corner. Nothing has to fit on a truck. If the good outlook is to the north-east and the fall runs south, the house can respond to both.
You also get to change your mind, within reason and within cost, while it's being built. And you get one licensed builder holding the whole thing, with the statutory warranty and insurance sitting over the complete house rather than split between a supplier who made the box and whoever connected it. Worth checking carefully on any transportable deal: who holds the licence, who holds the home building compensation cover, and who you call in three years when something moves. There's more on that in how to choose a home builder in NSW, and NSW publishes the licensing and contract requirements at nsw.gov.au.
On the standards side, both paths have to meet the same rules. A transportable is not held to a lower bar; the National Construction Code applies to the dwelling regardless of where it was assembled. Ask to see how the supplier demonstrates compliance, particularly on energy performance and waterproofing, because those are the ones that bite later.
The three questions that decide it
Can a semi-trailer and a crane actually reach the house position on your block, on the day, without taking out a power line or a tree you want to keep? If no, the conversation is over and you're building on site.
Is your ground close to level where the house goes, or can it be made level for a sensible number? Slope is the second veto.
Are you happy with a plan built from long rectangles? If you've been sketching layouts on the back of envelopes for two years, you're going to be frustrated by module geometry, and you should build on site.
Three yeses and a transportable is a fair option. One no and it isn't, and the earlier you know that the less of your money it costs you.
A version of this whole comparison plays out on granny flats too, where the kit and transportable market is much bigger — granny flat kit vs custom has that side of it, and if you're weighing builder types more broadly, custom home vs project home builder compares the two site-built approaches.
We build on site across Wollongong, the Illawarra and the Southern Highlands, and if you send us a block we'll tell you honestly whether access and slope would let a transportable work on it, even though it isn't what we sell. See how we run new homes, then use the contact page or ring 0434 037 851.
Want a hand with this at your place? Get a free quote or call 0434 037 851.