Bare concrete under a laundry, mudroom or internal wet area copes badly with the daily reality of the room: wet towels, muddy boots, spilled detergent, a washing machine that occasionally overflows without warning. Left uncoated, that concrete stains, dusts and eventually starts absorbing moisture in a way that’s hard to reverse without lifting the floor entirely. A proper internal floor coating fixes that permanently rather than temporarily, and on the Central Coast, where humidity keeps rooms like this damper for longer between uses, it’s one of the more overlooked upgrades a home can make.
This guide covers what an internal wet area coating actually involves, how it differs from an outdoor patio or garage job, and what an honest quote looks at before any colour or finish gets discussed.
Why internal wet areas need a different approach to a garage or patio
A garage floor deals with cars, dust and the occasional oil drip. An outdoor patio or path deals with weather, direct sun and general foot traffic. A laundry or internal wet area deals with something both of those largely avoid: sustained, repeated contact with water in an enclosed space, with nowhere for that water to evaporate to except the room itself.
That changes two things about how the job is approached. First, drainage and falls matter more here than almost anywhere else in the house. A laundry floor needs to shed water toward a floor waste rather than pool against a skirting board or door threshold, and if the original slab was never poured with that fall built in, correcting it becomes part of the resurfacing scope rather than an afterthought. Second, what sits beneath and around the coated area matters. A laundry adjoining a timber-framed hallway, a carpeted room, or a subfloor cavity is a genuinely different risk profile to a garage that opens straight onto a driveway, because water finding its way past a failed coating here has somewhere much more damaging to go.
Waterproofing and compliance come before the finish
Internal wet areas in Australian homes are covered by the waterproofing requirements of the National Construction Code and the relevant Australian Standard for wet area waterproofing (AS 3740), and while a laundry is treated less strictly than a bathroom in most builds, the same underlying principle applies: water needs a controlled path to a drain, and any point where the floor meets a wall, door or fixture is a place waterproofing can fail if it was never done properly or has degraded over time.
Before any coating goes down, a few things get checked:
- Existing waterproofing membrane, where one exists, particularly at the floor-wall junction and around the floor waste. A slab poured decades ago in an older Central Coast home may never have had a full internal membrane at all, in which case that gap needs addressing rather than simply coating over it.
- Falls to the floor waste. A laundry floor should fall consistently toward its drain point; ponding water sitting against a wall or door for hours after use is the first sign a fall is wrong or has never existed.
- Moisture already in the slab. Internal slabs on older homes, like garage slabs, can carry rising moisture from below. That’s assessed the same way it would be before an epoxy garage floor, since it affects primer choice and bond.
- Adjoining materials. Timber door jambs, carpet edges and plasterboard walls near a wet area are noted at inspection, since the coating’s edge detail needs to protect those materials rather than just look tidy.
Where waterproofing genuinely needs renewal rather than just a surface coating, that work is completed by an appropriately licensed waterproofing contractor before any decorative finish is applied, the same sequencing principle that applies to balcony resurfacing, another wet, enclosed surface where what’s underneath the coating matters more than the coating itself.
Finish options for laundries and internal wet areas
Polyurethane or moisture-tolerant epoxy systems are the most common choice for internal wet floors. Unlike a garage floor, which is judged mainly on toughness and appearance, an internal wet area coating is chosen primarily for how it copes with sustained dampness and how well it seals against a floor-wall junction. A textured, slip-resistant finish is generally specified rather than a smooth gloss, since a laundry floor is walked on with wet feet or wet socks more often than most rooms in the house.
Solid colour finishes are the practical default for a laundry: they’re easier to keep looking clean under a washing machine and don’t show lint and detergent residue the way a busier flake pattern can. Flake systems are still an option where the room doubles as a mudroom or boot room and a more forgiving, dirt-hiding finish is preferred.
Sealed, ground concrete (without a full coating build-up) suits laundries where the existing slab is sound, level and already reasonably presentable, and the brief is simply to make it easier to clean and more resistant to staining rather than a full transformation.
Whichever system is chosen, the coating needs to be compatible with the room’s actual conditions: continuous low-level moisture, occasional standing water, and detergent and cleaning chemical exposure that a garage floor never sees.
What actually needs fixing in an internal wet area
The most common issues homeowners raise about laundries and internal wet areas:
- Cracking or staining around the washing machine and tub, usually from repeated small overflows that have never had anywhere proper to drain.
- A floor that never quite dries, holding a damp smell or slight mustiness even after the room’s been aired.
- Lifting vinyl or tiles over an old slab, where the floor covering has failed and the concrete underneath is exposed, stained and rough.
- No floor waste, or one that’s poorly positioned, so water genuinely has nowhere sensible to go.
- A mudroom or boot-room floor that’s just bare, dusty concrete never intended to be seen, now that the room’s being used more deliberately.
An inspection separates a straightforward coating job on a sound, well-drained slab from one that needs waterproofing or drainage correction first, and it’s the second category, not the finish, that determines most of the cost.
Indicative cost guide for internal wet area coatings
| Job component | Indicative range (guide only) | Notes |
|---|---|---|
| Waterproofing assessment | Priced separately, often a fixed inspection fee | Confirms whether membrane or drainage work is needed before resurfacing is quoted |
| Membrane repair or renewal (where required) | Highly variable depending on scope | Quoted and completed by a licensed waterproofing contractor |
| Surface prep and coating, small laundry (~4-8 m²) | $600-$1,600 | Reflects minimum call-out economics on a small floor area |
| Surface prep and coating, larger mudroom or combined wet area | $1,200-$3,000 | Depends on area, edge detail and finish chosen |
| Correcting falls to an existing floor waste | Itemised per job | Only needed where drainage is genuinely wrong, not on every job |
All figures are indicative Australian guide ranges only. Because waterproofing condition and drainage vary so much from one home to the next, an accurate total is only possible after a proper inspection, and any membrane work is quoted separately from decorative coating.
Internal wet area floor coating FAQs
Can you coat our laundry floor without checking the waterproofing first?
We won’t recommend skipping that step. Coating over an unassessed or failing membrane just hides a problem that’s better dealt with properly, and in an enclosed internal room that problem is moisture reaching timber framing, plasterboard or a subfloor cavity rather than just a cosmetic issue. A waterproofing check is the first step in any honest quote for this kind of job.
Our laundry floor is original 1980s concrete with no coating at all. Is it too old to treat?
Age isn’t the disqualifying factor; moisture and slab condition are. Plenty of older Central Coast laundries coat well once ground, assessed for moisture and finished with a compatible system. Where readings are elevated, that’s factored into the primer choice rather than turning the job away.
What finish is easiest to keep clean under a washing machine?
A solid colour, textured finish is the practical default: it doesn’t show lint and detergent residue the way a busier flake pattern can, and the texture still gives useful grip on a floor that’s regularly wet.
Does a laundry floor need to be as slip-resistant as a pool surround?
It’s judged by the same principle, wet feet need reasonable grip, but the exposure is lower than a pool edge, so the finish and additive level are specified for typical laundry use rather than pool-area standards.
Is this the same system used on a garage floor?
Related but not identical. Garage coatings are chosen mainly for toughness against vehicle traffic and hot tyres. Internal wet area coatings are chosen mainly for how they cope with sustained dampness and how well the edges seal against adjoining walls and thresholds, which is why the two aren’t simply the same product applied in a different room.
Thinking about your laundry, mudroom or another internal wet area? Send a few photos through our quote form and we’ll give you an honest early read on what’s involved before anyone visits.