All articles · 6 min read

How wide should a doorless opening between two rooms be?

A doorless opening between two rooms should be at least 90 cm wide. 120-160 cm gives a genuinely open connection, and beyond 3 m it will usually need a structural beam.

Clear width — the figure that counts

When talking about how wide an opening should be, it is the clear width that matters: the distance between the finished, plastered or clad surfaces you can actually walk between. That is not the same as the hole in the structure.

Worked example: The carpenter cuts an opening of 1.40 m between the studs. The reveal is then clad with 12.5 mm plasterboard on each side, plus filler and paint — roughly 15 mm in total per side. The clear width becomes 1.40 − 0.03 = 1.37 m. If the reveal instead gets a 20 mm timber lining on each side, you end up at 1.32 m. The 8 cm difference sounds small, but it is exactly what decides whether a 130 cm wide cupboard gets through.

So: always agree with the tradesperson whether the figure you are discussing is the rough hole or the finished opening. That is the most common misunderstanding around an opening.

The widths, and what they can do

• 70-80 cm — an ordinary internal door width. Works as a passage, but feels like a door with no door. A laundry basket only just fits through; a coffee table does not.
• 90 cm — minimum for a genuine opening. This is where you can walk through with something in your hands, and it is also the width normally taken as the minimum for an accessible passage.
• 100-120 cm — this is where two people stop needing to give way to each other. A good width between an entrance hall and a kitchen, or between a kitchen and a utility room.
• 120-160 cm — the range where the two rooms start to read as one. Light from one window reaches into the other room. This is the typical width for "we opened up between the kitchen and living room".
• 180-250 cm — an opening where the wall is mostly just a pair of studs at each side. Almost always needs a structural beam if the wall is load-bearing.
• Over 300 cm — effectively a wall that is gone. The beam's size and cost climb steeply with the span, and both the beam itself and the supports it rests on need to be calculated.

How to find the width that suits YOUR room

Do not choose the width based on what looks good in a picture. Choose it based on what needs to pass through, and what the room can carry visually. Three questions decide it:

1. What is the widest thing you will ever need to get through? Measure it. A 220 cm sofa does not need to go through upright — it gets tipped — but a 70 cm fridge, a 140 cm double bed base and a 100 cm dining table do. Choose the opening's width so the widest fixed piece of furniture can pass with 5 cm to spare.
2. How much wall is left? A 4.80 m wall with a 3.00 m opening leaves 1.80 m split across two stretches. If they are not the same length, it looks lopsided — and a stretch under 40 cm reads as a mistake. Work it out before you draw: (4.80 − 3.00) ÷ 2 = 0.90 m on each side, if the opening is centred.
3. What needs to stand against the wall afterwards? This is the one people forget. Open up 2.60 m in a 4.00 m wall, and you have 1.40 m left — and an ordinary sofa arrangement or a tall cabinet needs 80-120 cm of unbroken wall space. Remove too much wall, and you get a room with nowhere left to put anything.

The height — half of the decision

An opening also has a top edge, and it matters just as much for the impression as the width does.

Standard height for an internal door is typically around 204-210 cm clear height. Make an opening at that height in a room with a 250 cm ceiling, and 40-46 cm of wall is left above the opening — a "header" that visually keeps the two rooms apart.

Full height is the other choice: the opening is taken all the way up to the ceiling, so there is no wall above it. This makes the rooms hang together in a completely different way, and it is often what people actually mean when they say they want to open things up. In return, it requires that nothing needs to be carried up there — and only a professional can determine that.

A middle ground: an opening at 220-230 cm height. Taller than a door, so it does not read as a door with no leaf, but with a band of wall left where a beam can sit hidden.

When does the opening need an engineer?

As soon as the hole is made in a load-bearing wall. That applies regardless of width — even a 90 cm opening in a load-bearing wall needs a header that has been properly calculated and that rests securely at both ends.

You cannot determine yourself whether a wall is load-bearing, and no app can do it for you. Wall thickness, whether the wall continues through the floors, and which way the floor structure spans are clues — not answers. The assessment has to be made on site by a qualified building surveyor or consulting engineer, and breaking through a load-bearing wall is work that must be approved by the authorities before it starts.

One practical point from the engineer's side: two narrower openings are often markedly cheaper than one wide one. Choosing between a single 4.00 m opening and two 1.60 m openings with a 60 cm stub of wall between them, the price difference in the beam work can be significant — and the two openings often give a more usable room, because the stub of wall becomes the place the sofa or the cabinet can stand.

Measure it on the drawing before you measure it on the wall

The opening's width is one of the figures that pays off best to test on paper. A drawing can be corrected in ten seconds; an opening cannot be made narrower again without rebuilding and repainting the whole wall.

In HouseSense, openings and doors appear on the floor plan with their dimensions, and because the app calculates from internal, wall-to-wall measurements, the figure you read is the same one you can check with a tape measure. In HouseSense you can draw an opening in to scale yourself, move it along the wall, and see how much wall is left on each side — and add the change as a scenario layered on top of the home as it is today.

Try this in particular: draw the opening at three widths — 90, 140 and 240 cm — and look at each one for where there is enough unbroken wall space left for furniture afterwards. The exercise takes five minutes and, surprisingly often, changes the decision.