Every mattress warranty sold in Australia is conditional on the mattress sitting on a base that supports it properly. The clause is in all of them. The number that makes it concrete, which is how far apart the slats can be, is published by some brands and not by others.
This matters most to people who are not buying a bed frame at the same time. A frame outlasts several mattresses, and a gap that was fine under a pocket-spring mattress can be too wide for foam.
Each figure below comes from the brand's own warranty, FAQ or support page, checked on 22 September 2026.
What each brand asks for
| Brand | Maximum slat gap | Where the figure comes from |
|---|---|---|
| Onebed | 5–7cm | The FAQ, given as an airflow recommendation |
| Ergoflex | 7.5cm | The FAQ, which also ties the base to the warranty |
| Koala | 7–8cm | A buying guide, not the warranty terms |
| Macoda | 8cm | The FAQ |
| Sleeping Duck | 12cm voids the warranty; 8cm or less recommended | The warranty itself |
| Emma | No figure published | — |
| Ecosa | No figure published | The warranty refers to an FAQ |
The published figures range from 5cm to 12cm, so there is no industry standard to fall back on.
A base with slats 7cm apart or less meets every figure in the table. 7cm is the widest gap that does, so it is the number to measure against when the mattress has not been chosen yet.
Sleeping Duck is the only brand that names a voiding number
Most brands describe the base they want. Sleeping Duck states the consequence. Its warranty says that using a slatted base with slats more than 12cm apart will void the ten-year mattress warranty, and recommends 8cm or less for performance.
That warranty is also the strictest on base type. It excludes use on a sprung base or an adjustable base, and it asks for support through the middle of the mattress rather than only at the edges. A Queen or King needs a centre rail that reaches the floor.
This is the opposite of Macoda, whose FAQ says the mattress is fine on a spring box, a slatted bed frame with gaps no bigger than 8cm, or the floor, and is compatible with adjustable bases.
Onebed asks for the tightest spacing, for a different reason
Onebed's 5–7cm is the narrowest figure of the group, and the FAQ gives it as a recommendation for humid parts of Australia, to avoid mildew or mould forming on the mattress. Frames with ventilation holes or a breathable fabric mesh are listed as alternatives.
That reasoning is worth separating from the others. Every other figure here is about the foam dipping between slats. Onebed's is about air moving underneath, which matters more in Brisbane and Darwin than in Melbourne.
Two brands publish no number
Emma and Ecosa both make the base a warranty condition without saying what qualifies.
Emma's warranty covers permanent sags or dips greater than 2.5cm that occur despite correct usage. Correct usage is not defined in terms of the base, and Emma's Australian FAQ does not give a slat figure. The 7.5cm often quoted for Emma comes from its UK site and from third-party reviews, not from anything Emma publishes here.
Ecosa's warranty is more specific about the mechanism and less useful in practice. It covers a visible indentation greater than 20mm, but only where the indentation has not resulted from use of an improper or unsupportive foundation as described in the FAQ. The FAQ page that sentence points to now redirects to a support home page, so the requirement a claim would be judged against is not published at a stable address.
The sag thresholds differ as well
Spacing is one condition of a warranty claim. The depth of the dip is another, and the brands do not agree on that one either.
| Brand | Indentation that counts as a fault |
|---|---|
| Onebed | More than 20mm |
| Ecosa | More than 20mm |
| Emma | More than 25mm |
| Sleeping Duck | More than 30mm |
A 25mm dip is a claim at Onebed and Ecosa, and normal wear at Sleeping Duck.
If the gap on an existing frame is too wide
The frame does not have to be replaced. A bunkie board, sometimes sold as a slat converter or a solid slat topper, is a thin rigid panel that lies on top of the existing slats and spreads the load across them. It raises the mattress by the thickness of the board, which changes how a fitted sheet sits and how high the bed ends up.
Plywood cut to size does the same job for less money, with one caveat: a solid sheet blocks airflow under the mattress, which runs against what Onebed asks for and is a poor idea in a humid climate. Drilling a grid of holes through it restores some of the airflow.
Adding slats is the other option on a timber frame, and it is the only one that leaves the bed at its original height.
Before buying a frame
Slat spacing is quoted by most bed frame retailers, though not always on the product page. Where it is missing, the number can be worked out from the slat count and the bed length. An Australian Queen is 203cm long, so a frame with 14 slats has roughly 145mm per slat, and the gap is that figure minus the slat width.
Buying the frame and the mattress from the same brand removes the question, because the two are specified against each other. Koala says all its bed bases are slatted platform designs with spacing chosen to suit its foam. The risk sits with frames bought separately, second-hand frames, and flexible or sprung slats, which Sleeping Duck excludes outright.
The trial and warranty terms these requirements sit inside are set out in full on our mattress trial and warranty comparison.
