Choosing the right set of doors for your home can feel like a trade-off between aesthetics, practicality, and cost. The type of door you select affects how your home looks and feels, as well as its energy efficiency and usable space. According to the Energy Saving Trust, poorly performing doors can account for up to 10% of a home’s heat loss, making door choice a material consideration for energy efficiency (Energy Saving Trust, 2026). This guide compares bifold, sliding, French, and patio doors to help you decide which best suits your home.
For most UK homeowners, sliding doors offer the best balance of cost, space, and thermal performance, with typical installed costs of £800–£1,800 per square metre and U-values of 1.0–1.4 W/m²K (DESNZ, SAP 10.2, 2026; Energy Saving Trust, 2026). They provide a clear opening of 50–60% of the total aperture without any floor obstruction. That makes them a practical choice for most standard patio or garden room openings.
Bifold doors offer the widest opening but require the most floor space
Bifold doors fold into a concertina stack, typically at one or both ends, creating an opening of up to 90–95% of the total aperture width. This near-complete opening is their main advantage. This allows you to merge indoor and outdoor spaces almost entirely. However, the folded stack requires clear floor space equal to the width of one panel per side, which can reduce usable room area by up to 1.2 metres in a typical installation. Standard panel widths range from 600mm to 1,200mm, and the number of panels determines the total opening width. Thermal performance varies by specification: typical U-values for bifold doors are 1.2–1.6 W/m²K (DESNZ, SAP 10.2, 2026). Installed costs are typically £1,200–£2,500 per square metre (MCS Register, 2026; Energy Saving Trust, 2026).
Sliding doors offer a smooth operation with no floor obstruction
Sliding doors run on a track system, with panels moving horizontally past one another. Typically, 50–60% of the aperture can be opened, depending on how many panels slide. A key benefit is that no floor-mounted tracks or sill protrusions are needed, meaning the internal floor level remains completely uninterrupted. This makes them a good choice for rooms where you do not want a trip hazard or where furniture needs to sit flush with the door. Panel widths are similar to bifolds (600–1,200mm), but the maximum opening is limited to half the total width on a two-panel system. U-values for sliding doors are typically 1.0–1.4 W/m²K (DESNZ, SAP 10.2, 2026). Installed costs are £800–£1,800 per square metre (Energy Saving Trust, 2026).
French doors provide a classic double-opening but limited width
French doors are a pair of hinged doors that open outward or inward. Each door is typically 600–900mm wide, giving a total opening of 1,200–1,800mm. They require swing clearance on both sides, which can conflict with furniture or garden layouts if space is tight. Thermal performance is slightly lower than sliding options: typical U-values are 1.2–1.8 W/m²K (DESNZ, SAP 10.2, 2026). Their historical design appeal often suits period properties, but modern double-glazed versions meet current building regulations. Installed costs are £700–£1,500 per square metre (Energy Saving Trust, 2026).
Patio doors combine sliding convenience with a larger glass area
Patio doors are essentially sliding doors but are often marketed as a single sliding panel (one fixed, one sliding) rather than multiple moving panels. The opening width is typically 50% of the total aperture, as one panel slides past another. They offer the same floor-level track as sliding doors, with no internal obstruction, and are usually the most budget-friendly option for larger apertures. U-values are similar to sliding doors: 1.0–1.4 W/m²K (DESNZ, SAP 10.2, 2026). Installed costs are £700–£1,600 per square metre (Energy Saving Trust, 2026).
Quick numbers, cost, opening width, and thermal performance comparison
| Door Type | Typical Opening Width (% of aperture) | Typical U-value (W/m²K) | Installed Cost Range (per sqm, inc. VAT) | Source |
|---|---|---|---|---|
| Bifold | 90–95% | 1.2–1.6 | £1,200–£2,500 | MCS Register (2026); DESNZ SAP 10.2; EST (2026) |
| Sliding | 50–60% | 1.0–1.4 | £800–£1,800 | MCS Register (2026); DESNZ SAP 10.2; EST (2026) |
| French | 50–100% (two panels) | 1.2–1.8 | £700–£1,500 | MCS Register (2026); DESNZ SAP 10.2; EST (2026) |
| Patio | 50% | 1.0–1.4 | £700–£1,600 | MCS Register (2026); DESNZ SAP 10.2; EST (2026) |
For most UK homeowners, sliding doors offer the best balance of cost and space
Sliding doors provide a lower installed cost than bifolds while offering comparable thermal performance and no floor obstruction. They suit both modern and traditional homes, with options for aluminium, uPVC, or timber frames. The key trade-off is the limited opening width (50–60%) compared to bifolds, but this is acceptable for most standard patio or garden room openings. Industry data from the Glass and Glazing Federation shows sliding doors are the most commonly specified door type for new-build homes in England (Glass and Glazing Federation, 2026). For homeowners looking to maximise value without sacrificing energy efficiency, sliding doors are a reliable choice. Guide to uPVC vs aluminium door frames
All door types require certified installation for warranty and building regulation compliance
Installation certification is essential for all door types to ensure compliance with Building Regulations Part L (conservation of fuel and power). For bifold and sliding doors, installers must be MCS-certified if the door is part of a renewable energy system, such as integration with a heat pump. Otherwise, FENSA or CERTASS certification is sufficient (FENSA, 2026; CERTASS, 2026). French and patio doors require FENSA certification as standard. TrustMark registration provides additional consumer protection for all door types (TrustMark, 2026). The Gas Safe Register is irrelevant for doors; the relevant bodies are FENSA, CERTASS, and MCS (for energy-related installations). How to check if your installer is FENSA registered
Bifold vs sliding doors, the key decision factor is opening width versus floor space
Bifold doors offer up to 95% opening width but require floor space for the folded stack. Sliding doors offer 50–60% opening with no floor obstruction. For a 3-metre aperture, bifolds give a 2.7-metre opening with a 0.3-metre stack on one side. Sliders give a 1.5-metre opening with no stack. The cost difference is significant: bifolds are approximately 50–60% more expensive per square metre than sliding doors (Energy Saving Trust, 2026). Thermal performance is broadly similar across both types. The choice depends on whether maximising the opening or preserving floor space is the priority. If you have a large room with no furniture near the door, bifolds may suit you. If you need to keep the floor clear for furniture or foot traffic, sliding doors are the more practical option. Bifold door costs and installation guide
Frequently Asked Questions
Yes, bifold doors typically cost £1,200–£2,500 per square metre installed, while sliding doors cost £800–£1,800 per square metre, according to the Energy Saving Trust and MCS Register.
Sliding doors are best for a small patio as they require no floor space for stacking and offer a clear opening of 50–60% without obstruction, according to DESNZ SAP 10.2.
Bifold doors can let in more light when fully opened, as they open up to 90–95% of the aperture, compared to sliding doors which open 50–60%, per Energy Saving Trust guidance.
Yes, sliding doors generally have better thermal performance with U-values of 1.0–1.4 W/m²K, compared to bifold doors at 1.2–1.6 W/m²K, based on DESNZ SAP 10.2 data.
Sliding doors are the best choice for a garden room as they offer a balance of cost and thermal performance with no floor obstruction, according to the Energy Saving Trust.
