Most rooms that feel "not quite right" are not let down by taste. They are let down by a handful of predictable mistakes: a sofa that swallows the room, a rug that floats, art hung too high, one sad downlight doing all the work. After designing and furnishing thousands of Australian homes, clinics and venues from our Port Melbourne showroom, these are the twelve mistakes we see most often, what they cost, and the simple rules that fix them.
A room planned with the Cocolea 360 Design Service: scale, light and materials decided before anything is ordered.
In this guide
Why small mistakes get expensive · The 12 mistakes · Measurements cheat sheet · Clinics, venues and offices · How to avoid them · FAQ
Why small design mistakes get expensive
In a luxury interior the expensive part is rarely the mistake itself. It is everything that follows. A made-to-order sofa that is 30 centimetres too long cannot simply be returned. A marble dining table that will not fit in the lift has to be craned in or sent back at your cost. A paint colour chosen before the fabrics clashes with everything you buy next. Each wrong decision tends to lock in the next one, which is why the cheapest time to fix a design is on paper, before anything is ordered.
The good news is that almost every mistake below has a clear rule behind it. Learn the rules and you will make better decisions whether you design your home yourself, work with a stylist or hand the whole project to a designer.
The 12 most common interior design mistakes
1. Shopping before you have a plan
The most common mistake of all is buying the exciting piece first: the statement armchair seen on Instagram, the chandelier from a hotel holiday, the dining table on sale. Without a floor plan, each purchase is a guess, and the room ends up as a collection of good pieces that do not belong together.
The fix: measure the room, draw it to scale (even on graph paper) and mark windows, doors, power points, vents and the way people walk through. Decide what the room is for, who uses it and when. Then build a list in order of size, starting with the largest pieces. If you would rather have this done for you, a Curate design session gives you a mood board, samples and a curated product list before you spend on furniture.
2. Getting scale and proportion wrong
Scale is where rooms succeed or fail. Oversized modular sofas are the classic error in Australian apartments, while undersized furniture in a large living room makes it feel empty and unfinished. Ceiling height matters too: low, deep pieces suit a standard 2.4 metre ceiling, while a 3 metre ceiling can carry taller bedheads, larger pendants and bigger art.
The fix: tape the footprint of large pieces on the floor and live with it for a day. As a guide, a sofa should be no more than about two thirds the length of the wall it sits against, and a coffee table about two thirds the length of the sofa. Our sofa guide and coffee table guide go deeper on proportions.
3. Choosing a rug that is too small
A rug that floats in the middle of the room, with no furniture touching it, makes the whole space look smaller and disconnected. It is one of the fastest ways to make an expensive room look unfinished.
The fix: in a living room, the front legs of every seat should sit on the rug, with about 20 to 45 centimetres of bare floor showing around the edges. Under a dining table, the rug should extend at least 60 to 75 centimetres beyond the table on every side so chairs stay on the rug when pulled out. In a bedroom, the rug should run under the lower two thirds of the bed and extend at least 50 centimetres either side. See our luxury rug guide or browse luxury rugs, including custom sizes.
4. Relying on one ceiling light
A single central downlight or pendant flattens a room, creates harsh shadows and makes even beautiful materials look cold. It is the most common reason a room "looks better in the photos".
The fix: layer three kinds of light. Ambient light fills the room (a chandelier or pendant on a dimmer), task light helps you read, cook or work (floor and table lamps), and accent light picks out art, joinery and texture. Aim for at least three light sources in a living room, keep colour temperature warm (around 2700K to 3000K at home) and put everything on dimmers. Explore luxury lighting and floor and table lamps.
5. Hanging art too high, or too small
Art hung near the ceiling, or a small print floating above a long sofa, is one of the easiest mistakes to spot and one of the easiest to fix.
The fix: hang art so its centre sits roughly 145 to 155 centimetres from the floor, the average eye level. Above a sofa or console, leave about 20 to 30 centimetres between the furniture and the bottom of the frame, and choose a piece (or group) about two thirds the width of the furniture below. Our guide to styling abstract art with Port Melbourne artist Catherine Hiller covers placement, scale and lighting, and you can browse original art and Catherine Hiller works in the showroom.
6. Choosing the paint colour first
Paint is the cheapest and easiest element in a room to change, yet many people choose it first and then try to match everything else to it. There are thousands of paint colours and only a handful of fabrics, stones and timbers you will truly love.
The fix: choose the hard-to-change elements first: flooring, stone, joinery timber, upholstery fabric, rug and art. Then choose a paint colour that sits comfortably with them, tested on large sample boards in the room at different times of day.
7. Buying everything as a matching set
A matching bedroom suite or a dining setting bought as one package is convenient, but it rarely looks considered. Rooms that feel luxurious usually look collected over time.
The fix: mix materials and shapes with a common thread. Pair a timber dining table with upholstered dining chairs, a sculptural console with a contrasting lamp, and a stone coffee table with a soft bouclé or velvet armchair. Repeat a colour, metal or curve two or three times so the mix still feels intentional.
8. Ignoring how people move through the room
A room can look perfect in a render and still be frustrating to live in if you have to turn sideways to get past the dining chairs or step around the coffee table to reach the sofa.
The fix: keep main walkways at least 900 millimetres wide and 1 metre where possible. Leave 400 to 450 millimetres between the sofa and coffee table, so it is within reach but easy to pass. Allow 900 to 1,000 millimetres between the edge of a dining table and a wall or cabinet so chairs can be pulled out comfortably. See the full list in the cheat sheet below.
9. Buying the wrong size dining table
Dining tables are often chosen by looks alone, and the result is either a table that seats fewer people than expected or one that leaves no room to walk around it.
The fix: allow about 600 millimetres of table edge per person (650 to 700 for generous, formal dining). A 1,500 millimetre round table seats four to six, a 1,800 millimetre round seats six to eight, and a 3,000 millimetre rectangle seats ten comfortably. Our dining table size and seating guide has a full chart, and the Melbourne-made kwerk Coco round dining table and Bentley dining table are available in two sizes, with custom sizes on request.
The kwerk Coco dining table, made in Melbourne in 1500 and 1800 mm diameters.
10. Choosing materials for the photo, not for real life
Polished white marble in a busy family kitchen, pale linen on a sofa used by children and dogs, or a high-gloss lacquer in a sunny room all look beautiful on day one. A year later they can be a source of constant worry.
The fix: match the finish to how the piece will be used. Honed stone hides etching better than polished, as we explain in our honed vs polished travertine guide. Performance velvets and tightly woven fabrics outlast loose weaves, and solid timber can be refinished where veneers cannot. Always see and touch physical samples; our material library and showroom are there for exactly that.
11. No focal point, or too many
Some rooms have nothing to hold the eye; others have a feature wall, a statement chandelier, a bold rug and a gallery wall all competing for attention.
The fix: give each room one hero and let everything else support it. That hero might be a fireplace, a large artwork, a sculptural dining table or a single investment piece of furniture. Australian made pieces such as the kwerk collection, a fireplace or a curved, sculptural piece work beautifully as the focal point when the rest of the room is quieter.
12. Underestimating lead times and delivery access
Luxury furniture is usually made to order, and lead times of 8 to 14 weeks are normal for bespoke upholstery and timber. Many people only discover this a few weeks before a move, a party or a clinic opening. Delivery access is the other surprise: tight stairwells, small lifts and narrow hallways stop more deliveries than people expect.
The fix: work back from your deadline and order the long-lead items first. Measure every doorway, stair turn and lift (including the internal height and depth) before ordering large pieces, and tell your supplier about access in advance. Our shipping policy explains how we deliver Australia-wide.
Interior design measurements cheat sheet
Save this table for your next project. These are the clearances and sizes we use every day in the studio.
| What | Rule of thumb |
|---|---|
| Main walkway | 900 mm minimum, 1,000 mm or more preferred |
| Sofa to coffee table | 400 to 450 mm |
| Coffee table length | About two thirds of the sofa length |
| Sofa length | No more than about two thirds of the wall |
| Living room rug | Front legs of all seating on the rug, 20 to 45 cm of floor showing at the edges |
| Dining rug | 60 to 75 cm beyond the table on every side |
| Bedroom rug | Under the lower two thirds of the bed, 50 cm or more either side |
| Table edge per diner | 600 mm (650 to 700 mm for formal dining) |
| Dining table to wall or cabinet | 900 to 1,000 mm |
| Art centre height | 145 to 155 cm from the floor |
| Art above furniture | 20 to 30 cm gap, about two thirds of the furniture width |
| Pendant above dining table | 75 to 85 cm from table top to the bottom of the pendant |
| Bedside table height | Within 5 cm of the mattress top |
| Home lighting colour temperature | 2700K to 3000K, on dimmers |
Mistakes in clinics, venues and offices
Commercial spaces add another layer: compliance with the National Construction Code and accessibility standards, durable commercial-grade finishes, and a brand experience that has to work for hundreds of people a week. The most common commercial mistakes we see are a reception that is the first thing patients or guests see but the last thing designed, waiting areas with hard, upright seating and harsh lighting, and finishes chosen for price that look tired within a year.
We have delivered fitouts for clinics, spas, bars, hotels and retail, including SOMA Spa in Sydney, Pier Hotel, Sip Champagne Bar, JC Le Bar and the four-tenancy Central BLVD Caroline Springs project. If you run a practice, our companion article on why patient-centred clinic design pays off looks at what the research and patients say, and our medical fitouts page explains how we work.
How to avoid these mistakes
Do the thinking before the shopping. A scaled plan, a clear brief and a materials palette will prevent most of the mistakes above. Write down how you live, what you want to keep, your budget and your deadline.
See it in person. Sit on the sofa, open the drawers, hold the stone sample in your own light. You are welcome to book a showroom viewing at 400 Plummer Street, Port Melbourne, and borrow fabric and finish samples to take home.
Get a second pair of eyes. Even confident decorators benefit from a professional check on scale, layout and lighting before committing to made-to-order furniture. Our Curate session is the easiest way to start, with a 60 minute showroom or virtual consultation, a personalised mood board, samples and a curated product list. For whole homes and commercial projects, our 360 Design Service manages everything from floor plan to installation. If you are wondering whether AI tools can do this for you, we compared the two in Do you still need an interior designer if you have ChatGPT?
Trade and design professionals can open a trade account for project pricing across our collections.
Follow @cocoleafurniture on Instagram for new arrivals, recent projects and styling ideas.
Frequently asked questions
What is the most common interior design mistake?
Buying furniture before making a plan. Without a scaled floor plan and a clear brief, pieces are bought one at a time and often end up the wrong size or style for the room. Measuring and planning first prevents most other mistakes, including oversized sofas and undersized rugs.
What size rug should I buy for my living room?
Choose a rug large enough for the front legs of every sofa and chair to sit on it, with roughly 20 to 45 cm of floor showing around the edges. In most Australian living rooms that means 2.4 x 3.4 m or larger. A rug that floats with no furniture touching it makes the room look smaller.
How high should I hang art?
Hang art so its centre is about 145 to 155 cm from the floor. Above a sofa, bed or console, leave a 20 to 30 cm gap between the furniture and the bottom of the frame, and choose a piece or group roughly two thirds the width of the furniture.
How much space do I need around a dining table?
Allow 900 to 1,000 mm between the table edge and the nearest wall or cabinet so chairs can be pulled out and people can walk behind them. Allow about 600 mm of table edge for each person.
Is it worth paying for an interior designer to avoid mistakes?
For most projects, yes. Made-to-order furniture usually cannot be returned, so one wrong size or finish can cost more than a design consultation. A short session such as Cocolea's Curate package checks scale, layout and materials before you spend on furniture.
How long does luxury furniture take to arrive?
Made-to-order pieces typically take 8 to 14 weeks, sometimes longer for imported or highly customised items. Order long-lead pieces first and check access, including doors, stairs and lifts, before you order.