Bunk and cabin beds have one requirement that ordinary beds don’t: the mattress has to be shallow enough to sit safely below the guard rail. Get that right, and the rest of the decision is about comfort, support and a cover you can wash. This guide walks through depth, size, support and materials, and explains what to look for when a child is sleeping several feet off the floor.
Depth Comes First
The guard rail on a bunk or cabin bed only works if there’s enough of it above the top of the mattress. UK safety guidance for bunk beds sets a maximum mattress depth, and the bed’s instructions or a label on the frame will tell you the limit for your model. Many bunk beds are designed for mattresses around 15cm to 16cm deep, and a standard adult mattress of 25cm or more is usually far too deep.
Simba’s Hybrid® Kids Mattress is a UK single with a shallower 16cm depth, designed specifically so it’s safe for use with bunk beds and cabin beds. Check the maximum depth on your bed before you order any mattress, and never exceed it.
Size
Most bunk and cabin beds take a standard UK single mattress, which is 90cm wide and 190cm long. Some take a European single, which is 90cm by 200cm, and some compact cabin beds take a shorter mattress. Measure the inside of the bed frame at the mattress base and match those numbers exactly. A mattress that’s too small leaves gaps at the edges, and one that’s too large won’t sit flat.
Simba’s Hybrid® Kids Mattress is a UK single. Simba doesn’t currently stock a bunk bed safe mattress in a European single size, so if your bed takes a EU single, check the dimensions carefully before you buy.
Support In A Shallow Mattress
A shallow mattress has less room for layers, so the quality of what’s inside matters more. Look for a design that combines a comfort layer with a supportive one, and for springs where you can find them. Springs respond individually to pressure, which keeps a growing child’s spine aligned as they move.
The Hybrid® Kids Mattress has five layers in its 16cm depth, including Simba’s patented Aerocoil® titanium alloy microsprings and graphite-infused Simbatex® foam, with a breathable cover that zips off for washing. Adults who’ve tried it on a bunk bed for a bedtime story tend to comment on how supportive it feels for its depth. It’s part of Simba’s range of hybrid mattresses, which all share the same medium-firm feel.
Age And Safety
Bunk and cabin beds aren’t safe for toddlers or children under three years old, whichever mattress you choose. For that age group, a cot bed with a firm, flat mattress is the right choice. Simba’s Hybrid® Cot Bed Mattress is double-sided, with a firmer side for babies under 12 months and a softer, sprung side for toddlers, and it conforms with BS EN 16890.
Once a child is old enough for a bunk, the top bunk is usually recommended for children aged six and over. Check the guidance that came with your bed.
Materials And Allergies
Children spend a lot of time close to their mattress, so the materials matter. Look for foams that are certified free from harmful chemicals, and for a cover you can take off and wash. Simba’s foams are CertiPUR® verified, which means they’re free from heavy metals such as mercury and lead.
Cover And Care
A washable cover is close to essential on a child’s bed. Spills, accidents and the occasional bout of illness all happen, and a cover that zips off and goes in the machine keeps the mattress fresh. Add a waterproof mattress protector on top, and you’ll rarely need to wash the cover at all. Simba’s TripleShield protectors come in Single and fit mattresses up to 40cm deep.
Rotate the mattress from head to toe every few months to keep wear even. You won’t need to flip it.
A Quick Buying Checklist
- The mattress depth is at or below the maximum shown on your bunk or cabin bed
- The size matches the inside of the frame exactly
- There’s real support inside, ideally springs as well as foam
- The foams are certified free from harmful chemicals
- The cover zips off for washing
- You’ve added a waterproof protector
- Your child is old enough for the bed
FAQs
Can I use a standard single mattress on a bunk bed?
Only if its depth is within the limit set by your bed. Most standard adult mattresses are 25cm deep or more, which is usually too deep for the guard rail to do its job. A purpose-made shallow mattress is the safer choice.
Is a 16cm mattress comfortable enough?
Yes, if it’s well made. A shallow mattress with springs and a quality foam layer can be more supportive than a deeper mattress made of foam alone. The Hybrid® Kids Mattress fits five layers into 16cm.
Do bunk beds need a different mattress for the bottom bunk?
The bottom bunk usually has more clearance, so a slightly deeper mattress may be allowed, but check the bed’s guidance. Many families use the same shallow mattress on both bunks so they can be swapped.
How long will a bunk bed mattress last?
Simba’s Hybrid® Kids Mattress comes with a 200-night trial and a 10-year guarantee when bought new from Simba, so it’s built to last well beyond the bunk bed years.
Can the Kids Mattress be used on a normal single bed frame?
Yes. It’s a standard UK single, so it works on any single bed base as well as bunk and cabin beds.
