A bunk bed sleeps two children in the floor space of one. In a shared room that's the whole point, and nothing else comes close.
But there are more decisions here than in any other bed category, and one rule that isn't negotiable. This covers both.
The rule: the top bunk is 6 and over
Children under 6 must not use the top bunk. This is set by BS EN 747, the British standard for bunk beds and high beds, and it applies to every bunk bed regardless of how low the frame is.
It exists because spatial awareness, coordination and the ability to respond safely when disorientated at night all develop significantly between four and seven.
The bottom bunk is a different matter. There's no equivalent restriction, which means a bunk bed works perfectly well for mixed-age siblings: the older child goes on top, the younger one underneath. That's the most common arrangement we sell into.
When the younger one turns six and wants to swap, a detachable bunk gives you options. More on that below.
The two measurements
Ceiling height. The child on the top bunk needs to sit up comfortably with clear space above their head. Measure directly above where the bed will stand, not the highest point of the room. Sloped ceilings and loft conversions are where this catches people out.
Mattress depth. Usually a 15 or 16cm maximum on the top bunk. Guard rails are designed to sit a set height above the mattress surface, and most high-street singles are 20cm or deeper, which removes 5cm of rail.
Our bunk bed mattresses are built at 15cm for exactly this reason.
Which type of bunk?
Standard bunk
Two singles stacked. The simplest and usually the cheapest way to sleep two.
- HoppeKids Shorty Bunk Bed, from £359.00
- Nyla Cashmere Low Bunk Bed, £379.99
Detachable bunk — the one that lasts longest
Splits into two separate single beds. Worth paying for if there's any chance the children will want their own rooms, or if the younger one will want the top bunk when they turn six.
It's the single feature that most extends the useful life of a bunk bed, and it costs little or nothing extra at the point of purchase.
- Pippa Detachable Bunk Bed with Pull-Out Trundle, £399.99
- Heritage Detachable Bunk Beds with Trundle, £499.00
- Little Folks Classic Detachable Bunk Beds, £499.00
Bunk with a trundle — sleeps three
A third mattress on a low rolling frame that slides away underneath. It's how you sleep three in the footprint of one bed, and it's the version most families choose once sleepovers start.
The trundle usually takes a shallower mattress, around 10cm, so it clears the frame above when it slides back.
- Haven Storage Bunk Bed with Pull-Out Trundle, £615.00
- Easy Staircase Bunk Bed with Pull-Out Trundle, £684.99
- Salto Bunk Bed with Optional Trundle, £475.00
Bunk with storage
Drawers, shelves or a wardrobe built into the frame. One piece of furniture instead of three, which matters more in a shared room than anywhere else.
- HoppeKids Shorty Bunk Bed with Drawers, from £475.00
- Nook Bunk Bed with Wardrobe & Drawers, £699.99
- Belgravia Bunk Bed with Wardrobe & Drawers, £799.99
Family bunk — a double underneath
A small double on the bottom and a single on top. Good for a parent reading at bedtime, for two younger children sharing the bottom, or for guests.
Triple and quadruple
For three or four children in one room. Worth measuring carefully, since ceiling height becomes the limiting factor rather than floor space.
- The King Quadruple Bunk, £399.99
Low bunks
Lower overall height, which helps with low or sloped ceilings. The 6+ rule for the top bunk still applies.
Covered in more detail in our guide to low bunk beds.
Ladder or staircase?
A ladder takes up almost no space and costs less. A staircase is easier and safer to climb, and the steps usually have drawers built in, so the storage comes free.
The trade-off is footprint. A staircase adds meaningfully to the bed's length or width, so measure before committing to one.
Two things to check on any bunk: which side the ladder attaches, and whether it's reversible. Some are fixed, and finding out after assembly is an expensive lesson.
You'll need two mattresses. Or three.
The most commonly forgotten part of buying a bunk bed, and the one that ruins a delivery day.
- Standard bunk: two mattresses, both within the stated maximum depth
- Bunk with trundle: three, and the trundle one is usually shallower, around 10cm
- Shorty bunk: two shorty mattresses at 75 x 175cm, not standard singles
- Family bunk: a small double and a single, plus a trundle mattress if fitted
Order them at the same time as the bed. See our bunk bed mattress range, or the bed size guide for the right dimensions.
When a bunk bed isn't the answer
- Low or sloped ceiling. Look at low bunks, or two separate beds.
- Both children under 6. The bottom bunk is fine, but you're buying a two-tier bed and only using one tier.
- Sleepwalking, or difficulties with balance.
- You'll be changing the sheets. Making the top bunk is awkward, and it's the most common thing parents say they hadn't considered.
- A big age gap. A teenager and a toddler sharing a bunk rarely works for long.
Safety in use
- Guard rails on all sides of the top bunk, fitted and secure
- Mattress within the stated maximum depth on the top bunk
- No gap between the bunk and the wall that a child could slip into
- Nothing hung from the frame: no ropes, bags, skipping ropes or fairy lights
- One person on the top bunk at a time
- Fixings re-tightened every few months, and after any move or reconfiguration
- If a detachable bunk is put back together as a bunk, re-run the full check and confirm all guard rails are refitted
Full detail on our bed safety guidance page.
Before you order
- Measure ceiling height directly above where the bed will stand.
- Measure the floor space, including the ladder or staircase projection.
- Check whether it detaches, if there's any chance you'll want two separate beds later.
- Check the maximum mattress depth for the top bunk.
- Count the mattresses. Two, or three with a trundle.
- Plan the assembly. Two adults, one and a half to three hours. We offer room-of-choice assembly if you'd rather not.
Common questions
What age can a child sleep on the top bunk?
Six and over, set by BS EN 747. There's no equivalent restriction on the bottom bunk.
Can a 4 year old have a bunk bed?
On the bottom bunk, yes. Not on the top. A bunk bed works well for mixed-age siblings for exactly this reason.
How much ceiling height do I need for a bunk bed?
Enough for the child on top to sit up comfortably with clear space above their head. Measure directly above the bed's position and check against the bed's overall height.
What mattress depth for a bunk bed?
Usually a 15 or 16cm maximum on the top bunk. Check the specific figure on the product page. The bottom bunk can often take a deeper one.
Do bunk beds split into two singles?
Some do, some don't. It's listed on each product page as detachable. If it matters, check before ordering, since it isn't a modification to make yourself.
What's a trundle?
A third mattress on a low rolling frame that slides away under the bottom bunk. It's how a bunk bed sleeps three without taking more floor space.
Ladder or stairs?
Stairs are easier to climb and usually have storage built in, but they add to the bed's footprint. A ladder takes almost no space and costs less.
Is the top bunk hotter?
Yes, usually by two to three degrees, because heat rises. A lower tog duvet on the top bunk is the simplest fix. More in our guide to room temperature and children's sleep.
Still deciding what type of bed? Read our kids' bed buying guide, or browse all bunk beds.
