Cost estimates only: Any building, material or upgrade figures on this page are indicative, not fixed prices or quotes. Confirm current written costs, specifications and inclusions directly with your builder, supplier or relevant trade.
What Is an Undermount Sink?
An undermount sink is mounted from below the benchtop surface, with the sink basin hanging beneath the countertop cutout. The benchtop material (typically stone) forms the visible edge around the sink opening — there is no rim or lip sitting above the bench surface.
This is in contrast to a topmount (drop-in) sink, where the sink drops into a cutout from above, with a visible rim resting on the benchtop surface.
Tip
Topmount vs Undermount Sinks
| Factor | Topmount (Drop-In) | Undermount |
|---|---|---|
| Installation method | Drops in from above | Mounted from below |
| Visible rim on bench | Yes — sits above benchtop | No — seamless bench surface |
| Ease of cleaning | Harder — rim traps grime | Very easy — wipe directly into sink |
| Compatible benchtops | All materials | Stone only (engineered, natural) |
| Appearance | Standard/functional | Premium, modern |
| Typical builder inclusion | Yes — standard | Upgrade |
| Upgrade cost (typical) | — | $300–$800 |
Pros & Cons
Pros
- Seamless, modern appearance — no visible rim
- Easiest to clean — wipe directly from bench into sink
- No rim to collect grime, food residue or discolouration
- Integrates beautifully with stone benchtops
- Higher perceived quality and resale appeal
Cons
- Almost always a paid upgrade ($300–$800)
- Requires stone benchtop — incompatible with laminate
- More complex installation during build
- If sink seal fails, moisture can damage cabinet below (with any sink type)
- Slightly more complex to replace if needed
Sink Materials
- Stainless Steel (304 grade)Most common. Hygienic, durable, easy to clean. Look for 1.0mm+ thickness. Cheaper sinks use thinner steel that dents and resonates.
- Stainless Steel (316 marine grade)Saltwater resistant — worth specifying if you're in a coastal environment.
- Stone Composite (Granite/Quartz compound)A premium option. Highly resistant to scratching, chipping and staining. Heavy. Popular in luxury kitchens. Cost is 2–4x stainless.
- Fireclay/Ceramic (Butler/Belfast style)Classic, apron-front design. Very durable and scratch-resistant but can chip. High cost. Popular in farmhouse or Hamptons-style kitchens.
Included or Upgrade?
Typically Included
Topmount Stainless Steel Sink (Standard Grade)
Included as standard by most builders. Size (single or double bowl) and quality varies. Confirm the specification in your inclusions list.
Typically an Upgrade
Undermount Stainless Steel Sink
Paid upgrade. Typical cost: $300–$800. Must be combined with a stone benchtop — laminate is not compatible.
Typically an Upgrade
Stone Composite or Fireclay Sink
Premium material upgrade. Budget $800–$2,500+ depending on material and configuration.
Common Builder Upgrades
Common Builder Upgrade
Undermount Sink (Combined with Stone Benchtop)
Common Builder Upgrade
Tapware Finish Upgrade (Matte Black, Brushed Nickel)
Frequently Asked Questions
Frequently Asked Questions
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