The Complete UK Guide
Complete Guide to Loft Conversion & Room in Roof Conversions
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Loft Conversion Guide helps UK homeowners understand the different conversion options, costs, planning requirements, and installation process before transforming unused roof space. LAMTANS Engineering shares expert retrofit guidance from our Manchester base, covering energy-efficient upgrades, insulation solutions, and room-in-roof conversions across the UK.
- TrustMark Registered
- RECC Accredited
- PAS2035 Compliant
- ECO4 Eligible Projects
The Basics
What Is a Loft Conversion?
A loft conversion is the process of transforming an unused attic or roof space into a fully functional living area, such as a bedroom, home office, study, playroom, or additional family space. By adapting the existing roof structure, homeowners can increase usable space without extending the footprint of their property.
Loft conversion vs room in roof conversion: a traditional loft conversion creates a new habitable room from an unused loft area. A room in roof conversion upgrades an existing, partially converted loft to improve insulation, comfort and building regulation compliance.
Loft conversions are a popular home improvement option across the UK because they can add valuable living space, improve property functionality, and potentially increase house value. The best conversion type depends on your roof structure, available headroom, property layout, budget and planning requirements.
The Five Main Types
What Are the Different Types of Loft Conversions?
Loft conversions come in several designs, each suited to different property types, roof structures and space requirements. From simple Velux roof window conversions to larger Dormer, Hip to Gable and Mansard designs, the right option depends on how much additional space you need and what your home can accommodate.
Velux Loft Conversion
Usually the most affordable option because it uses the existing roof structure with minimal alteration. Roof windows are installed into the existing slope to create a brighter, more functional loft space.
- Indicative cost: £15,000 – £25,000
- Typical timeline: 2–3 weeks
- Planning permission: Usually not required, subject to permitted development rules
Dormer Loft Conversion
A dormer extends the existing roof vertically, creating additional headroom and floor space. Dormers are popular because they create significantly more usable space than roof-window-only conversions.
- Indicative cost: £25,000 – £45,000
- Typical timeline: 4–6 weeks
- Planning permission: Often permitted development (check conservation area status)
Hip to Gable Loft Conversion
Ideal for detached and semi-detached homes with hipped roofs — where the roof slopes down on three sides. The sloping side is extended to create a vertical gable wall, opening up the loft.
- Indicative cost: £35,000 – £55,000
- Typical timeline: 6–8 weeks
- Planning permission: Usually required
Mansard Loft Conversion
A Mansard conversion creates the maximum usable floor space, but usually requires more extensive structural work — making it the highest-cost option of the main types.
- Indicative cost: £45,000 – £70,000
- Typical timeline: 8–10 weeks
- Planning permission: Always required
Room in Roof Conversion
Unlike a new loft conversion, a room in roof conversion upgrades an existing loft room with poor insulation, outdated electrics or inadequate heating — improving comfort, safety, energy efficiency and compliance with current standards.
- Indicative cost: £10,000 – £20,000
- Typical timeline: 3–5 weeks
- Planning permission: Usually not required
All costs and timelines are indicative guide figures — actual prices depend on your property, roof structure, access and specification. A free survey confirms an accurate written quote.
Indicative Guide Prices
Loft Conversion Costs by Type
Loft conversion costs vary depending on the conversion type, property structure, required modifications and level of finish. The table below shows indicative UK guide prices, typical timelines and planning permission considerations for the main options.
| Type | Indicative Cost | Typical Timeline | Planning Permission |
|---|---|---|---|
| Velux | £15,000 – £25,000 | 2–3 weeks | Usually not required |
| Dormer | £25,000 – £45,000 | 4–6 weeks | Often permitted development |
| Hip to gable | £35,000 – £55,000 | 6–8 weeks | Usually required |
| Mansard | £45,000 – £70,000 | 8–10 weeks | Always required |
| Room in roof | £10,000 – £20,000 | 3–5 weeks | Usually not required |
Additional costs to consider (indicative)
- Ensuite bathroom: +£5,000 – £10,000
- Dormer window: +£3,000 – £6,000
- Stairs: +£2,000 – £4,000
- Building control fees: £500 – £1,000
All figures are indicative guide prices, not fixed quotes or guarantees. Your free survey confirms an accurate written quote for your property.
Step by Step
How Does a Loft Conversion Process Work?
Whichever conversion type you choose, the process follows the same structured approach — from survey and design through structural work, insulation and services to final certification.
Free Consultation & Site Survey
We check headroom, roof structure and access to confirm what's possible in your loft.
Design & Planning
We handle planning permission and building control applications on your behalf.
Structural Work
Flooring, stairs, roof alterations and steel beams where required.
Insulation (PAS2035 Compliant)
Insulation fitted between and over rafters, to party walls and the floor. This stage determines the room's year-round comfort, energy efficiency and building-regs thermal compliance — the step that makes the whole conversion work.
First Fix
Electrics, plumbing, heating and ventilation installed before the walls are closed up.
Plastering & Decoration
New plasterboard, skim finish and decoration throughout the new room.
Second Fix
Sockets, switches, radiators and flooring — the finishing work.
Final Sign-Off & Certification
Building control sign-off and final certification, all handled for you.
Planning & Permitted Development
Do You Need Planning Permission for a Loft Conversion?
Planning permission requirements depend on your property type, location, design and whether your project falls under permitted development rights. Many loft conversions can be completed without planning permission, but certain restrictions and approvals may apply.
You may need planning permission if:
- Your property is located in a conservation area
- Your property is listed
- You exceed the permitted development volume limits (below)
- Your design involves significant roof alterations
- Your proposed conversion does not meet permitted development conditions
LAMTANS can support you through the planning and approval process — including understanding requirements, preparing documentation and coordinating with relevant professionals where needed.
Retrofit Matters
Why Is Loft Insulation Important in a Loft Conversion?
Loft insulation is a critical part of any loft conversion because it improves comfort, energy efficiency and compliance with building regulations. Without suitable insulation, a converted loft can lose heat quickly during winter and become harder to keep comfortable throughout the year.
In pitched roof loft conversions, insulation is usually installed between and over the rafters to reduce heat loss while achieving the required thermal performance standards.
LAMTANS combines loft conversion expertise with retrofit knowledge — helping homeowners improve insulation, reduce energy waste and create efficient living spaces. We follow PAS2035 principles when upgrading insulation as part of energy improvement works.
Funding Support
Can You Get Grants for a Loft Conversion?
Government grants generally do not cover the full cost of a loft conversion, because funding schemes are designed to improve energy efficiency rather than create additional living space. However, some insulation and energy improvement measures included within a loft project may qualify for partial support, depending on eligibility.
Energy improvements that may receive support include:
- Loft insulation upgrades
- Pitched roof insulation between and over rafters
- Room in roof insulation improvements
- Other eligible energy efficiency measures under available schemes
Eligibility depends on factors such as household circumstances, EPC rating, property type and current government scheme rules. Funding availability and requirements can change over time — support may be partial, and a top-up contribution may be required. Not sure if your insulation upgrades qualify? Contact LAMTANS for a free grant eligibility check.
Check Your ECO4 Grant EligibilityTrusted Specialist
Why Choose LAMTANS for Your Loft Conversion?
Choosing the right loft conversion company is about more than creating extra space. A successful conversion requires knowledge of structural requirements, insulation standards, building regulations and energy efficiency. LAMTANS combines retrofit expertise with loft conversion experience to deliver comfortable, compliant and energy-efficient living spaces for homeowners across the UK.
Retrofit Industry Specialists
Not general builders — we specialise in insulation and energy-efficient conversions for UK housing stock.
PAS2035 Compliant
Insulation and energy improvement works follow recognised British retrofit standards.
Full Project Management
One point of contact managing your entire conversion from survey to sign-off.
Planning & Building Control Handled
We manage planning permission and building control applications and approvals for you.
Free, No-Obligation Quotes
Honest advice with no pressure — and a free site survey before any written quote.
Manchester-Based, Nationwide Coverage
Based in Manchester and serving Stockport, Oldham, Droylsden, Ashton-under-Lyne, Tameside and Greater Manchester, with nationwide UK coverage.
Our Credentials
Common Questions
Frequently Asked Questions
How much value does a loft conversion add to my home?
Some industry estimates suggest a well-executed loft conversion may add around 10–20% to a property's value, though this varies significantly by property, location, conversion quality and market conditions — it should never be treated as a guaranteed return.
Do I need building regulations approval?
Yes. All loft conversions must meet building regulations for structural stability, insulation, fire safety, electrics and ventilation. We handle the whole approval process for you, through to final certification.
How long does a loft conversion take?
As a typical guide: a Velux conversion takes 2–3 weeks, a dormer 4–6 weeks, and a mansard 8–10 weeks. Timelines depend on scope, access and weather — we confirm a schedule for your project after the free survey.
Will a loft conversion make my house colder?
No. Properly insulated loft conversions improve your home's overall thermal efficiency and can reduce heat loss through the roof — that's why the insulation stage is the critical step in our process.
Can I convert my loft if I have a low roof?
Often, yes — a dormer or mansard conversion can create headroom even with a low existing roof. We assess what's possible for your property during the free survey.
Is LAMTANS accredited?
Yes. We are TrustMark Registered, RECC Accredited and PAS2035 Compliant, and we deliver ECO4 eligible projects. You can view our credentials on our accreditations page.
Free Survey & Quote
Ready to Plan Your Loft Conversion?
Whether you're planning a Dormer, Velux, Hip to Gable, Mansard or Room in Roof conversion, our team can help you understand the best option for your property, budget and energy efficiency goals. Not sure which type is right for your home? Book a free consultation — we'll assess your property and advise you within 72 hours following your free survey.
Free survey · No obligation · Advice within 72 hours following your free survey
- TrustMark Registered
- RECC Accredited
- PAS2035 Compliant
- ECO4 Eligible Projects