Double Storey Extensions
Twice the Space, Maximum Value
Add a kitchen extension below and bedroom above for the best return on investment. Perfect for growing families who need space now.
Why Go Double Storey?
Build up, not out. Adding a second floor costs only 40% more but gives you 100% more space—the best value per square meter in London.
Cost per Square Meter
Typical project: Open-plan kitchen-diner below (30-40sqm) + master bedroom with ensuite above (25-35sqm). This singlehandedly solves both the "cramped kitchen" and "need another bedroom" problems London families face.
Master Bedroom Suite
Bedroom + ensuite + wardrobes
Open-Plan Kitchen-Diner
Kitchen + island + bi-fold doors
Is a Double Storey Right for You?
This extension type suits specific situations perfectly.
Growing Families
You need both a bigger kitchen AND another bedroom. Build both at once rather than extending twice.
Value Maximizers
You've done the math: double storey adds £180-250k value for £80-120k spend. Best ROI in London extensions.
Forever Homers
You love your location and neighbourhood. Building up means you don't need to trade up and move boroughs.
Dulwich Double Storey Project
From 3-bed terrace to 4-bed family home with stunning kitchen.
Before
After
From Empty Garden to Two-Floor Extension
Foundations & Ground Floor
Weeks 1-8: Deep foundations, ground floor walls, structural steel beams, floor slab. Side and rear walls built to full height.
First Floor Structure
Weeks 9-12: First floor joists, bedroom walls, roof structure. The extension takes shape vertically.
Weatherproofing & Services
Weeks 13-16: Roof tiles/covering, windows, bi-folds, plumbing, electrics, heating. Extension is watertight.
Finishing & Handover
Weeks 17-20: Plastering, tiling, kitchen fit, bathroom installation, decorating. Final snagging and completion.
Double Storey Extension Costs
4m x 4m Double Storey (32sqm)
Basic finishes, standard fittings
5m x 5m Double Storey (50sqm)
Mid-range spec, quality finishes
6m x 6m Double Storey (72sqm)
Full spec, premium materials, luxury ensuite
Full architectural service • Structural engineer • Building regulations • All materials & labour • Ground + first floor build • New roof • Windows & bi-folds • Full electrics & plumbing • Kitchen & bathroom fit • Decorating • 10-year warranty
Double Storey Extension FAQs
Usually yes. First floor additions almost always require full planning permission. But our success rate is 97% because we design with planning policy in mind from day one. We handle the entire application as part of our service.
About 40% more in total cost, but you get 100% more space. Single storey 30sqm = £60k. Double storey 60sqm = £85k. You're paying £25k extra for an additional 30sqm—that's only £833/sqm for the first floor. Unbeatable value.
Not recommended. Building both together is far more cost-effective. If budget is tight, we suggest building the ground floor now (with foundations rated for a future first floor) and adding the second storey in 2-3 years.
This is the #1 planning concern. We conduct a sun path analysis and design the extension to minimize overshadowing. Most objections can be avoided with thoughtful design—stepped walls, angled roofs, or positioning windows strategically.
Other Extension Options
Ready to Build Up?
Book a free consultation. We'll assess feasibility, discuss planning, and provide a detailed quote with 3D renders of your two-floor extension.
⭐ 150+ double storey extensions completed