How to Make Extensions Feel Cosy (Not Cold and Boxy)

Modern extensions can feel wonderful: light, spacious, and perfectly proportioned. Or they can feel like you've added a glass box to your home that's freezing in winter, boiling in summer, and never quite comfortable. 

The difference comes down to some simple decisions during design and construction that either create warmth and atmosphere or leave you with a space that feels stark and unwelcoming.

After 13 years building extensions across Hull, we've learned what makes new spaces feel like genuine parts of your home rather than modern additions you're not quite sure about. Here's how to get it right.

Getting Ceiling Heights Right

Vaulted ceilings sound appealing, but they often make extensions feel cold and echoey. Heat disappears upwards, and the space feels disconnected from the rest of your home, where ceilings are lower.

We usually recommend ceiling heights that roughly match your existing rooms. If your main house has 2.4m ceilings, taking your extension to 2.6m or 2.7m feels spacious without feeling vast. You get extra light and space without creating a room that feels like a different building entirely.

Not Too Much Glass

Everyone wants light in their extension. But floor-to-ceiling glass on multiple walls creates spaces that feel exposed and uncomfortable. You end up with nowhere to put furniture and no sense of cosiness.

Glass works best on one side, usually facing the garden. A wall of bi-fold doors is perfect. But the other walls need to be mostly solid so you have space for sofas, shelving, and all the things that make a room actually usable and comfortable.

Choosing Warmer Flooring

Polished concrete and large tiles look great in photos, but they're cold underfoot and make every sound echo. They can make your extension feel more like a showroom than somewhere you want to relax.

Engineered wood flooring feels much warmer and cosier. If you need tiles for practicality in the kitchen area, consider wood or carpet in the seating area. Underfloor heating helps with any hard flooring, making it comfortable even in winter. Big rugs also add warmth and help with the echo problem.

Using Warm Colours and Materials

All-white walls and grey floors might look modern, but they often feel cold and clinical. Adding warmer colours and natural materials makes a huge difference to how cosy your extension feels.

Consider warmer paint colours rather than pure white. Soft creams, warm greys, or even a feature wall in a gentle colour create atmosphere. Exposed brick on one wall adds texture and warmth. Wooden elements like beams, shelving, or window frames bring natural warmth that balances all the glass and plaster.

Getting the Shape Right

Very narrow extensions feel like corridors rather than rooms. Very long, thin spaces don't work well for furniture and can feel awkward to use.

Aim for proportions that feel room-like. Generally, extensions work best when they're at least 3.5m wide. Think about where your sofa will go, where the dining table fits, and whether you can move around comfortably. If furniture only works pushed against walls, the space will feel cramped.

Lighting for Comfort

Downlights everywhere create harsh lighting that feels cold. They're useful over worktops and tables, but you need other lighting too for a cosy feel.

Add pendant lights over dining tables or kitchen islands. These create focal points and softer light. Include some wall lights or plan where lamps will go. Dimmer switches are essential, letting you lower the lighting in evenings so the space feels comfortable rather than bright and clinical.

Connecting to Your Existing Home

Extensions that feel completely separate never quite work. The transition between old and new needs thought.

A wide opening between your existing house and extension makes both spaces feel connected. If possible, remove the wall entirely or create an opening of at least 2.5m to 3m wide. Carry some materials through from your existing rooms, like similar flooring in the doorway area, so it feels like one home rather than two different spaces stuck together.

Dealing with Echo

Hard floors, large windows, and high ceilings all create echo. This makes extensions feel cold and uncomfortable, even if they look beautiful.

Soft furnishings help enormously. Curtains or blinds on big windows, rugs on hard floors, sofas with lots of cushions, throws: all these absorb sound and make the space feel quieter and cosier. Even just adding these simple things once you move in makes a noticeable difference.

Heating That Works

Underfloor heating is brilliant in extensions, but big windows lose heat quickly. Sometimes underfloor heating alone isn't enough on cold days.

We often add a radiator or two near the large glazed areas as backup. This ensures your extension stays warm even in the depths of winter. A separate thermostat for your extension also helps, so you can control the temperature independently from the rest of your house.

Small Details That Matter

Sometimes small ideas make the biggest differences. Built-in storage keeps clutter away and makes spaces feel calmer. A window seat creates a cosy spot and adds character. Even small architectural touches like alcoves for shelving or slightly deeper window sills make extensions feel more homely and less like empty boxes.

Making It Personal

The most important thing is creating a space that works for how you actually live. Think about where you'll sit, how you'll use the space in the evenings, and whether it'll feel comfortable year-round, not just on sunny days when estate agent photos look perfect.

We're happy to talk through how to make your extension feel cosy and comfortable from the start, and ensure you get all the benefits of an extension from day one. After 13 years building extensions across Hull, we know which simple decisions make the biggest difference to how much you'll actually enjoy the space.

Give us a call on 07934 237607 or email dbconstructionhull@outlook.com to discuss your extension plans.