Compare garden rooms and conservatories on thermal performance, cost, property value impact, year-round usability, and planning requirements. A practical guide to choosing the right option.
Garden Room vs Conservatory: Which Should You Choose?
Garden rooms and conservatories both provide additional living space connected to your garden, but they are fundamentally different buildings with different strengths, weaknesses, and costs. If you are deciding between the two, this guide will help you understand the key differences and make the right choice for your needs.
The Fundamental Difference
A conservatory is a glazed structure attached to the house, typically with a glass or polycarbonate roof and large areas of glazing in the walls. It is designed to let in maximum natural light and provide a visual connection to the garden.
A garden room is a detached, insulated building in the garden, separate from the house. It has solid, insulated walls, a solid roof, and windows sized for light and views rather than for maximum glazing. It is designed for year-round comfort and practical use.
This fundamental difference — attached and glazed vs detached and insulated — drives most of the practical differences between the two.
Thermal Performance: The Critical Difference
The single biggest difference between a garden room and a conservatory is thermal performance, and this is where conservatories have a well-documented problem.
A traditional conservatory with a polycarbonate or glass roof acts like a greenhouse: it traps solar heat in summer, making the space uncomfortably hot (often 35–45°C on a sunny day), and it loses heat rapidly in winter because glass and polycarbonate are poor insulators. The result is a space that is too hot to use for several months in summer and too cold to use for several months in winter. Many homeowners find their conservatory is only comfortable for 4–6 months of the year.
A well-insulated garden room, by contrast, maintains a stable internal temperature year-round. With wall U-values of 0.25–0.30 W/m²K and a solid, insulated roof, the room stays warm in winter (with modest heating) and cool in summer (because the insulated roof and walls block solar heat gain). A garden room is typically comfortable for 12 months of the year.
| Factor | Conservatory | Garden Room |
|---|---|---|
| Summer comfort | Poor (overheats) | Good (insulated roof blocks heat) |
| Winter comfort | Poor (loses heat rapidly) | Good (well-insulated, efficient to heat) |
| Months of comfortable use | 4–6 months | 12 months |
| Heating cost (winter) | High (poor insulation) | Low–moderate (good insulation) |
| Cooling needed? | Often yes (blinds, fans, AC) | Rarely (ventilation usually sufficient) |
Modern conservatories with solid or hybrid roofs (part solid, part glazed) perform significantly better than traditional designs, but at that point the cost approaches that of a garden room and the thermal performance is still inferior to a fully insulated building.
Cost Comparison
Conservatories are generally cheaper to build than garden rooms, but the total cost of ownership (including heating, cooling, and maintenance) can be higher.
| Cost Element | Conservatory (15m²) | Garden Room (15m²) |
|---|---|---|
| Build and installation | £10,000–£25,000 | £18,000–£35,000 |
| Foundations | Included | £1,500–£3,000 |
| Electrics | £500–£1,500 | £1,500–£3,000 |
| Annual heating cost | £400–£800 | £150–£350 |
| Annual maintenance | £200–£500 (cleaning, seals) | £50–£150 (cladding treatment) |
| Replacement/major repair (20 years) | £3,000–£8,000 (roof, seals) | £500–£2,000 (re-stain, minor repairs) |
Over a 20-year period, the lower running costs and maintenance of a garden room can offset the higher initial build cost.
Planning and Building Regulations
Both conservatories and garden rooms usually fall under Permitted Development and do not require planning permission, subject to the standard size and height limits.
Conservatories are exempt from Building Regulations provided they are thermally separated from the house by external-quality doors (such as patio doors or French doors) and have an independent heating system with separate temperature controls. If you remove the separating doors and open the conservatory into the house, Building Regulations apply.
Garden rooms are exempt from Building Regulations if they are under 15m² (or under 30m² with conditions). See our building regulations guide for the full rules.
Property Value
Estate agents increasingly view garden rooms more favourably than conservatories when valuing properties. A well-built garden room is seen as a genuine addition to the usable space of the property — a home office, gym, or studio that adds practical value. A conservatory, particularly an older one with a polycarbonate roof, is often seen as a liability rather than an asset, because buyers know it will be uncomfortable for much of the year and may need replacing.
A quality garden room typically adds 5–10% to property value. A conservatory adds 3–7% if it is modern and well-maintained, but an older conservatory in poor condition can actually reduce the perceived value of a property.
Usability and Flexibility
A garden room is more versatile than a conservatory. Because it is a separate, insulated building with its own power supply, it can be used for activities that would be impractical in a conservatory: a home office (where you need consistent temperature and no glare), a gym (where you need ventilation and reinforced flooring), a music room (where you need sound isolation), or a bar (where you need mood lighting and a controlled atmosphere).
A conservatory excels at one thing: providing a light-filled space with a strong visual connection to the garden. If your primary goal is a bright dining room or sitting area where you can enjoy garden views, a conservatory may be the right choice — provided you accept the seasonal comfort limitations.
Which Should You Choose?
Choose a garden room if you want a space that is comfortable and usable 12 months of the year, you need it for a specific purpose (office, gym, studio, bar), you value energy efficiency and low running costs, or you want a building that adds genuine value to your property.
Choose a conservatory if your primary goal is a light-filled dining or sitting area attached to the house, you are on a tight budget, you accept that the space will be uncomfortable in extreme weather, or you prefer the visual style of a glazed structure.
Consider a modern solid-roof conservatory or orangery if you want the best of both worlds — an attached structure with good thermal performance. These cost more than a traditional conservatory but perform significantly better.
Next Steps
If a garden room is the right choice for you, our free planning wizard can help you understand the likely cost, size, and specification for your project. You can also read our full three-way comparison of garden rooms, extensions, and conservatories, or browse our supplier directory to find garden room companies in your area.