Securing Planning Permission is only half the battle. Building Regulations (Building Regs) ensure your new home is structurally safe, fire-resistant, and energy-efficient. Here is what you need to know for 2026.
Planning vs. Building Regulations
It is crucial to understand the difference:
- Planning Permission: Concerns the appearance, size, and impact on neighbors/environment. (Does it look right?)
- Building Regulations: Concerns the technical construction standards. (Will it stand up and be safe?)
Key Areas of Compliance
1. Structure
Calculations from a Structural Engineer are mandatory for steel beams, lintels, and foundations. Depth of foundations is critical in London clay soil (often 1m+).
2. Fire Safety
For loft conversions, this is major. You typically need fire doors on all habitable rooms leading to the stairwell to create a protected escape route. Mains-powered smoke alarms are essential.
3. Thermal Efficiency (Part L)
With 2026 standards, insulation requirements are strict. Extensions need high-performance insulation in floors, walls, and roofs to minimize heat loss. Glazing must also meet specific U-values.
4. Ventilation (Part F)
New rooms need adequate background ventilation (typically trickle vents in windows) and extract fans in kitchens/bathrooms to prevent mold and condensation.
Routes to Approval
1. Full Plans Application: You submit detailed technical drawings to the council BEFORE starting. They check and approve them.
Best for: Major works where you want certainty.
2. Building Notice: You just inform the council you are starting (48 hours notice). No initial plan check. The inspector checks work as it proceeds.
Best for: Small, simple works.
3. Private Approved Inspector: You hire a private company instead of the council. They send the “Initial Notice” to the council.
Best for: Speed and responsive service.
The Completion Certificate
Never pay your builder their final retention fee until you have the Building Control Completion Certificate in your hand. You will struggle to sell or re-mortgage your house without it.
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![The Complete Guide to Kitchen Extensions in London [2026]](https://elmoredesignbuild.com/wp-content/uploads/2026/01/kitchen-extension-5-300x200.jpg)
