Is it cheaper to build a conservatory or extension?
So you're thinking about adding space to your home, yeah? The big question everyone asks is whether a conservatory or a full extension is the better deal money-wise. Short answer? Conservatories are almost always cheaper to build than a traditional extension. But honestly, it's not that simple—costs bounce around based on size, what you build it with, the foundations, and what you actually plan to do with the space. Let's dig into the nitty-gritty.
What is the average cost difference between a conservatory and an extension?
Industry numbers suggest a basic conservatory—say, a 3m x 3m setup—can run you between £4,000 and £15,000. Compare that to a single-storey extension of the same size, which often lands somewhere between £20,000 and £40,000, maybe more. The big gap? Foundations and structural stuff. Extensions need full building regulations, deeper foundations, pricier materials like brick and blockwork. Conservatories? They're lightweight—mostly glazing and a simple roof—so installation's way cheaper. Simple as that.
Are there hidden costs that make a conservatory more expensive in the long run?
Here's the thing—that lower upfront cost can trick you. Conservatories have a reputation for being freezing in winter and boiling in summer unless you splash out on specialist glazing, insulation, or heating. An extension, though, hooks right into your home's existing heating and insulation, so energy bills stay lower. And don't forget planning permission—some conservatory designs need it if they're too big or a certain shape, while some extensions slide under permitted development rights. Always, always check local rules. Seriously.
Which option adds more value to your home?
Property folks tend to agree—a well-built extension typically boosts your home's value more than a conservatory. Extensions feel like permanent, usable space that just fits with the rest of the house. Conservatories? They can seem a bit awkward—hard to furnish, less versatile. But here's the twist: a modern conservatory with a solid roof and good insulation? That can add decent value too, especially if you use it year-round. General rule: extensions give better ROI, but conservatories are friendlier on your wallet upfront.
What are the key factors that affect the final cost?
Loads of things swing the final price tag:
- Size and shape: Bigger or weird shapes? Costs creep up for both.
- Materials: uPVC conservatories are the budget pick; timber or aluminium cost more. Brick-and-block extensions are standard but pricey.
- Foundations: Extensions need deep, expensive foundations. Conservatories sometimes get away with simpler slab bases.
- Roof type: Glass roof is cheaper but sucks at insulation. A solid tiled roof on a conservatory hikes the cost but makes the room usable.
- Planning and regulations: Professional fees, permissions, building control—all add up.
- Location: Labour costs vary—London and the South East? Yeah, you'll pay more.
Data table: Cost comparison for a 3m x 3m space
| Feature | Conservatory (basic) | Single-storey extension |
|---|---|---|
| Average build cost | £4,000 – £15,000 | £20,000 – £40,000 |
| Foundations | Shallow (often slab) | Deep (trench fill or strip) |
| Materials | uPVC, glass, polycarbonate | Brick, block, timber, tiles |
| Heating/insulation | Poor unless upgraded | Integrated with home |
| Planning permission | Often not needed (check) | Often requires approval |
| ROI (value added) | 50–70% of build cost | 70–85% of build cost |
Checklist: Should you choose a conservatory or an extension?
- Budget: Under £15,000? Conservatory's pretty much your only shot. Got £20,000+? Think about an extension.
- Use: Sunroom or occasional hangout? Conservatory works. Need a permanent kitchen, bedroom, or living space? Go extension.
- Planning: Check if your project fits under permitted development or needs full planning permission—don't assume.
- Energy efficiency: Want a year-round room? Invest in a solid roof and double glazing for a conservatory, or just build an extension.
- Resale value: Planning to sell soon? Extension generally adds more value.
- Time: Conservatories go up in 2–4 weeks; extensions take 6–12 weeks or longer—plan accordingly.
Expert insight: “I always tell homeowners to think about how they’ll use the space. A conservatory is a great budget-friendly option for a light-filled room, but if you need a fully integrated living area, an extension is worth the extra investment. Always get at least three quotes and check for hidden costs like VAT on building work.” — Sarah Jenkins, Chartered Surveyor
Frequently asked questions (FAQ)
Can a conservatory be converted into an extension later?
Yeah, you can convert a conservatory into something more permanent. Usually means replacing the roof with a solid one, adding insulation, upgrading the walls. Costs? Anywhere from £5,000 to £15,000 depending on the work. It's a decent compromise if you want to spread the cost over time.
Is a conservatory cheaper to build than a wooden extension?
Generally, yeah. A uPVC-and-glass conservatory still beats a timber-framed extension on price—those need more skilled labour and fancier materials. But a high-end conservatory with hardwood frames and a solid roof? That can creep close to the cost of a basic extension.
Do I need building regulations for a conservatory or extension?
Extensions? Yes, building regulations are usually a given. Conservatories might be exempt if they meet certain conditions—floor area under 30m², separated from the house by external walls, with its own heating controls. But don't gamble—check with your local authority.
What is the cheapest type of conservatory?
The cheapest is usually a lean-to design with uPVC frames and polycarbonate roof panels. You're looking at £3,000–£5,000 for a small one. But heads up—it offers the least insulation and won't last as long. A basic Victorian or Edwardian style with double glazing costs a bit more but holds up better.
Resumen breve
- Costo inicial: Un invernadero (conservatory) es significativamente más barato de construir que una ampliación (extension), con precios desde £4,000 frente a £20,000+.
- Costos a largo plazo: Las ampliaciones suelen ser más eficientes energéticamente, lo que puede ahorrar dinero en calefacción, mientras que los invernaderos pueden necesitar mejoras.
- Valor de reventa: Una ampliación generalmente añade más valor a la propiedad, con un retorno de inversión del 70–85%, frente al 50–70% de un invernadero.
- Uso previsto: Elija un invernadero para un espacio de uso ocasional o de temporada, y una ampliación para una habitación permanente y totalmente integrada.
