Which mattress works in a wall bed?

The 30 cm rule (and why it exists)

The standard SBLM mechanism is engineered for mattresses up to 30 cm thick. This isn't a marketing limit — it's the literal arc of the folding hinge. Above 30 cm, the mattress hits the cabinet face before the bed reaches its locked-up position; the mechanism either won't lock or strains the latch every cycle.

A wall bed company that says "any mattress fits" is either using a different mechanism geometry or is about to disappoint you. Always ask for the thickness limit in writing.

Brand-by-brand fit (HK retail, Q1 2026 spec sheets)

Spec sheets change. Always check your specific model's height card at the retailer or measure with a ruler before ordering. We can also measure for you at our Kwun Tong showroom — bring a photo.

Foam vs spring vs hybrid in a wall bed

Pocket spring (most common in HK)

• Pro: Holds shape best when stored vertically. Springs don't sag from gravity-on-edge.
• Pro: Cooler in HK summer humidity than pure-foam.
• Con: Can squeak slightly on the way up the first 10–20 folds (springs settling). Quiets after that.
• Verdict: Default best choice for wall beds. ~70% of our customers use pocket-spring.

Memory foam / Tempur

• Pro: No springs to fatigue.
• Pro: Best for couples with very different weights or for back-pain sleepers.
• Con: Foam compresses in HK humidity over years stored vertically — slight permanent indent at the strap line is possible.
• Con: Holds heat — known issue in HK summer regardless of wall bed.
• Verdict: Works well, but rotate it 180° at month 6, 18, 30 to even out the strap-line indent.

Hybrid (foam top + pocket spring base)

• Pro: Best of both for sleep quality.
• Con: Often the thickest category — most premium hybrid mattresses are 30+ cm and need our custom deeper-frame box at +HKD 1,800 (cabinet labour).
• Verdict: Worth the upgrade if your premium mattress already exceeds 30 cm. Tell us the model on day 1.

The 35 cm workaround (custom deeper frame box)

If your mattress is 30–35 cm — common on Tempur Adapt, Sealy Trianon, Simmons Black, premium hybrids — we can custom-machine the frame box's stop-position deeper at additional cabinet labour ~HKD 1,800. The mechanism itself is unchanged; we're just giving the foot of the bed an extra 5 cm of clearance on the way up.

Above 35 cm we don't go — physical hinge geometry runs out. If your mattress is 36+ cm, you either replace it or live with a permanent bed.

Three mattresses you should never put in a wall bed

1. Anything over 35 cm. See above. The hinge will not work.
2. Pure latex without a base layer. Latex slabs slide on the strap; you'll wake up with the mattress half-off the frame. Foam-on-spring or foam-on-coil construction is fine.
3. Water beds and air beds. Self-explanatory but worth saying — both will fail in a wall bed (water spills, air leaks at the valve under repeated stress).

The HK humidity caveat

Whatever mattress you pick, store it with the breathable side facing the cabinet opening (not the wall). HK humidity reaches 90%+ for weeks in spring; trapped moisture between mattress and wall is how mould starts. We design the cabinet with a 2 cm air gap behind the bed for exactly this reason — but only if you orient the mattress correctly.

If you're not sure

Tell us the brand + model + thickness on day one. We'll tell you "fits standard," "fits with the deeper-box upgrade," or "honestly, replace the mattress" — whichever is true. The deeper-box upgrade is HKD 1,800 of our cost; we don't push it as a profit centre. Saving you a mattress decision is the goal.