Is a Loft Conversion or Extension Better for ROI in 2025?
Many homeowners know they want more space, but the big question remains:
Should you build up or build out?
A loft conversion and a ground floor extension both increase floor area, improve usability and boost property value — but each delivers different benefits, planning requirements and return on investment.
In this guide, we’ll break down cost, planning, build time, and long-term value — so you’ll know which route is smarter for your home.
What’s the Average ROI on a Loft Conversion?
A well-designed loft conversion typically returns 18–25% uplift on property value.
Why? Because you’re adding an extra bedroom — often with an en-suite — and this shifts your home into a higher price bracket.
Typical examples:
Existing Layout / After Loft Conversion / Uplift Potential
3-bed house / 4-bed house + bedroom + en-suite / Higher resale band
4-bed house / 5-bed + loft master suite / Premium appeal
Terraced house / loft dormer / Maximises space without extending footprint Strong rental potential
Why loft conversions score well for ROI:
No land loss (you keep the garden!)
Often permitted development — planning not always needed
Cheaper per m² vs ground floor builds
Bedrooms add more value than living space alone
Faster build time — ~6–10 weeks on average
Best for homeowners who want more bedrooms & long-term resale appeal.
What ROI Can You Expect from a Ground Floor Extension?
Ground floor extensions typically return 12–20% depending on:
• size,
• glazing quality,
• kitchen spec,
• and whether layout improves flow.
They excel when the goal is:
a large open-plan kitchen/living area
improved family space
indoor–outdoor entertaining
more usable everyday living
Typical ROI by extension type:
Extension Type / ROI Range / Notes
Rear Extension / 12–17% / Most planning-friendly and popular
Side or Wraparound / 15–20% / Major transformation + high desirability
Double-Storey / 18–25%+ / Best total value return, but highest cost
Small infill extension / 8–12% / Good for space, less impactful on value
Best for families planning to stay long-term & improve lifestyle.
Which One Wins for Cost vs Value?
Factor / Loft Conversion / Ground Floor Extension
Typical Cost Range / £45,000–£85,000+ / £65,000–£200,000+
Build Duration / 6–10 weeks / 10–24+ weeks
Planning Required? / Often PD* / More likely needed
Adds Bedroom? / Yes / Optional
Adds Living Space? / Sometimes / Yes — main strength
ROI Potential / Strong / Potentially higher with layout transformation
If value-per-pound is top priority then loft wins.
If lifestyle & resale impact is the aim then extension often delivers more wow.
*Most lofts fall under permitted development. Extensions may require planning depending on size, height and proximity to boundaries.
If unsure, Draw & Plan can advise instantly.
Quick Decision Guide for 2025
Choose a loft conversion if you want:
another bedroom or master suite
the best return for the lowest cost
minimal disruption during construction
a faster approval and build route
Choose an extension if you want:
a bigger kitchen/family hub
a modern open-plan lifestyle
stronger emotional buyer impact
room to entertain, dine & live differently
Best-case ROI?
Many clients achieve it by combining both — loft adds a bedroom, extension improves liveability.
Thinking of extending or converting?
Let Draw & Plan draft your design options for both — side-by-side — so you can see:
Build cost difference
Space gained per m²
Projected valuation uplift
Planning complexity
Best resale / rental position
We provide planning drawings, building regulation plans & support right through to approval.
Book Your Design Call
Enquire at: www.drawandplan.com
Or request your free scope review
We help homeowners get approval first time, and build with confidence.
Disclaimer: This article is for general informational purposes only and does not constitute legal or professional advice. Always consult relevant professionals and local authorities before undertaking any development or change of use.
