Bunk Beds Glossary: Every Term You Need to Know

This bunk beds glossary explains the terms you will see when shopping for a bunk bed in the UK, from berths and guard rails to trundles, triple sleepers and mattress depth. Knowing the language makes it much easier to compare designs, check safety features and choose a bed that suits your room and your children. The terms are grouped by topic, so you can jump straight to the part you need.

Product descriptions often assume you already know what a mid sleeper or a tie bar is. If you are browsing our modern bunk beds UK range for the first time, keep this guide open alongside it.

Types of Bunk Bed

Bunk bed: A bed frame with two or more sleeping platforms stacked vertically. The standard design has one single bed above another, sharing the same footprint.

Standard bunk: A bunk bed of typical height, usually with enough space beneath the top bunk for a child or teenager to sit up on the lower bunk.

Low bunk: A shorter bunk with the top berth closer to the floor. Sometimes called a low line or cabin bunk, it suits rooms with lower ceilings and younger children, and it makes changing bedding easier.

Triple sleeper: A bunk that sleeps three. Most commonly, this has a double or small double lower berth with a single above. The term is also used for bunks with a trundle beneath.

Three tier bunk: A bunk with three single berths stacked vertically. These are the tallest designs and need high ceilings.

Double bunk: Usually a bunk with a double lower berth, though some designs have doubles on both levels. Check the product details to see which size each level takes.

L shaped bunk: A bunk where the top berth sits at a right angle to the lower one, creating an L shape. This opens up space beneath the top bunk for a desk or storage, but takes up more floor area.

Staircase bunk: A bunk reached by a set of steps instead of a ladder. The steps often contain drawers or cupboards.

Futon bunk: A bunk with a single bed above and a futon or sofa bed below, which converts from seating to a bed.

Splitting or separable bunk: A bunk that can be taken apart and used as two separate single beds. This adds flexibility as children grow.

Related Bed Types

Mid sleeper: A single raised bed, lower than a bunk, with space beneath for storage, a play area or a small desk. Only one person sleeps in it.

High sleeper: A single raised bed at roughly bunk height, with room beneath for a desk, sofa or wardrobe. Again, only one sleeping space.

Cabin bed: A single bed raised a little off the floor, with built in drawers or cupboards beneath. Cabin beds are lower than mid sleepers. Our modern bedroom furniture UK sale collections include a variety of beds that sit alongside bunks in family homes.

Daybed: A single bed designed to look like a sofa, with a back and sides. Some daybeds include a trundle beneath.

Parts of a Bunk Bed

Berth: Each individual sleeping level of a bunk bed. A standard bunk has two berths, an upper and a lower.

Top bunk: The upper berth, reached by a ladder or stairs.

Lower bunk: The berth at floor level, sometimes called the bottom bunk.

Guard rail: The barrier around the top bunk that stops the sleeper rolling out. Also called a safety rail. A safe top bunk has guard rails on all sides, with an opening only where the ladder or stairs meet the bed.

Ladder: The means of reaching the top bunk on most designs. Ladders may be vertical or angled, and some can be fitted to either side or end of the bed.

Reversible ladder: A ladder that can be fitted on the left or right of the bed, so you can choose the layout to suit the room.

Uprights or posts: The vertical corner sections that support the whole frame.

Side rails: The long horizontal sections running along the sides of each berth, supporting the slats.

End panels: The headboard and footboard of each berth, which may be solid, slatted or open.

Tie bars: Horizontal bars that connect the upper and lower sections and add rigidity.

Slats: The strips of wood or metal that span the frame and support the mattress. Slats allow air to circulate beneath the mattress.

Sprung slats: Slightly curved slats that flex under weight, adding a little give and comfort.

Solid base: A flat board instead of slats. Solid bases are rare on bunks because they restrict airflow.

Storage and Extras

Trundle: A low bed on castors that slides out from beneath the lower bunk. It provides an extra sleeping space for guests and tucks away when not in use.

Pop up trundle: A trundle that can be raised to the same height as the bed above, creating a wider sleeping area. These are less common on bunks.

Underbed drawers: Drawers beneath the lower bunk, usually on castors or runners, for bedding, clothes or toys.

Integrated shelving: Shelves built into the frame, often at the end of the bed or within the staircase.

Canopy or tent: A fabric cover fitted to the frame to turn the lower bunk into a den. Always follow the guidance for safe fitting.

Castors: Small wheels fitted to drawers or trundles. Some are designed for hard floors and others for carpet.

Mattress Terms

UK single: The most common bunk size, with a mattress measuring 90cm by 190cm.

Small single: A narrower size, typically 75cm by 190cm, used on some compact or children’s designs.

Small double: A mattress measuring 120cm by 190cm, often used for the lower berth of a triple sleeper.

Double: A UK double mattress measures 135cm by 190cm.

Maximum mattress depth: The deepest mattress the manufacturer recommends for each berth. On the top bunk this is essential, because a deeper mattress reduces the height of the guard rail above the sleeping surface.

Trundle mattress: A thinner mattress designed to fit inside a trundle so it can slide away beneath the bed. Our mattresses UK sale selection includes sizes suited to bunks and trundles.

Safety Terms

BS EN 747: The British and European standard that covers bunk beds and high beds for domestic use. It sets requirements for guard rails, ladders, gaps and structural strength. Look for frames that state compliance.

Headroom: The clear space between the top of the upper mattress and the ceiling. There should be enough for the sleeper to sit up comfortably.

Clearance: The space between the lower mattress and the underside of the top bunk. This determines how comfortably someone can sit up on the lower berth.

Minimum age for top bunk: Top bunks are generally not recommended for children under six.

Entrapment gaps: Spaces in the frame where a child’s head or limbs could become trapped. The safety standard sets limits on these gaps.

Assembly and Care Terms

Flat packed: Supplied in pieces for home assembly, which makes delivery up stairs and through narrow doors easier.

Allen key: The hexagonal tool used to tighten the bolts on most bunk beds. Keep it safe for regular checks.

Fixings: The bolts, screws, dowels and washers that hold the bed together.

Powder coating: A hardwearing finish used on metal frames, baked on for an even surface.

Lacquer or varnish: A clear protective coating on wooden frames.

Solid wood: Frames made entirely from natural timber, such as pine or oak.

Engineered wood: Boards made from wood fibres or particles bonded together, often finished with a veneer or foil.

Using This Glossary

When comparing bunk beds, look at the type, the size of each berth, the maximum mattress depth, the overall height and the safety standard. Knowing these terms makes product descriptions much clearer and helps you ask the right questions.

If you are still deciding between a bunk and separate beds, our children’s beds UK range offers alternatives such as cabin beds and single frames. For older children who want a little more comfort, our guide to upholstered single beds for UK children and teenagers explores another option. When you are ready, you can browse everything at Furniture in Fashion, with free delivery to most UK mainland postcodes.

Frequently Asked Questions

What is the difference between a bunk bed and a high sleeper?

A bunk bed has two or more sleeping spaces stacked vertically. A high sleeper has one raised bed with open space beneath for a desk, sofa or storage.

What does triple sleeper mean?

A triple sleeper is a bunk that sleeps three, usually with a double or small double lower berth and a single above, or a standard bunk with a trundle.

What size mattress does a standard bunk bed take?

Most take a UK single mattress measuring 90cm by 190cm. Always check the product details and the maximum mattress depth for each berth.

What safety standard should a bunk bed meet in the UK?

Look for compliance with BS EN 747, the British and European standard covering bunk beds and high beds for domestic use.