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How Much Does a Dormer Loft Conversion Cost in 2025?
- For a small dormer loft covering around 20 m2, expect to pay £30,000–£35,000. A medium-sized dormer, around 30 m2, costs £45,000–£45,000. Larger loft conversions over 40m2 cost £45,000–£50,000.
- The cost depends on many factors, mainly the dormer type. Shed dormers are simpler, while gable dormers cost more but improve livability.
- Potential hidden costs can arise with dormer conversions like structural issues, scaffolding hire, waste removal, or VAT payment. It's advised to keep 10–15% of the total budget as a contingency for unexpected overages.
Dormer loft conversions can be a significant investment. However, the returns on investment and the multitude of benefits will make it worthwhile.
Here, we will dive deep into all the costs involved, starting with the cost per type of dormer, the most important supply, and labour costs. In addition, we will uncover the expenses associated with planning permissions and building regulations.
If you’re wondering how to save money on your dormer conversion, keep reading as we explore money-saving strategies, tips, as well as financing options including government grants and home improvement loans.
Ready to start your conversion? Skip the hassle of looking for quotes— simply fill out our quick form to receive up to 3 free quotes from trusted local specialists. Click below to get started!
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Dormer loft conversion cost in the UK
In 2025, the average cost of a dormer loft conversion in the UK ranges from £30,000 to £50,000. The final price will depend on the size and features of the conversion.
For a small dormer loft covering around 20 m2, expect to pay £30,000–£35,000. A medium-sized dormer, around 30 m2, costs £45,000–£45,000. Larger loft conversions over 40m2 cost around £45,000–£50,000.
A two-bedroom dormer conversion with an en-suite bathroom is one of the most expensive options. This type of conversion provides ample living space and is highly popular among homeowners. For a high-quality two-bedroom dormer you can expect to pay £45,000–£55,000. The en-suite bathroom alone, adds around £5,000–£7,000 to the overall cost.
Though expensive, a two-bedroom ensuite dormer conversion maximises the potential of the loft space. The investment into comfort and livability is well worth it for many homeowners. Careful planning and budgeting allow the creation of the perfect living area in the roof space.
Factors that impact the cost of a dormer conversion
The total cost of a dormer loft conversion varies largely and depends on several key factors:
- Size of the dormer: Larger conversions naturally cost more in materials and labour compared to smaller, more modest spaces.
- Type of the dormer: Shed dormers tend to be simpler in design than more complex gable dormers. However, gable dormers often maximise space and feel more integrated. Opting for a gable style usually increases the project cost but enhances livability.
- The length of the project: Expedited timelines with quick turnarounds typically mean higher costs due to extended labour hours and overtime fees. Most standard conversions take 3–6 months from start to finish.
- Geographic location within the UK: Construction costs in London and the South East are generally higher than in other regions. Materials, deliveries, and scaffolding are more expensive in these areas. Professional tradespeople may have premium rates in desirable metropolitan areas.
- Finishes and materials quality: Opting for high-end wood windows, stone floors, or luxury fixtures adds expense compared to vinyl, laminate, and standard fittings.
Carefully weighing all these factors allows you to arrive at an accurate estimate of your dormer conversion cost. Understanding the influences also provides realistic budgeting.
Cost by type
Different types of dormer conversions have different costs. The table below summarises typical price ranges based on dormer type, along with estimated project timelines:
| Dormer type | Average cost | Completion time |
|---|---|---|
| Rear dormer | £25,000–£45,000 | 8–10 weeks |
| Side dormer | £30,000–£50,000 | 8–10 weeks |
| L-shaped dormer | £35,000–£55,000 | 10–12 weeks |
| Full dormer | £40,000–£60,000 | 12–14 weeks |
More complex dormer conversions like an L-shaped and full dormer typically cost more and take longer to complete. However, if you want to increase your loft's size substantially, these might be the right options for you.
Supply costs
The supply costs comprise a significant portion of the total dormer conversion budget. The major supply expenses for a medium-sized dormer conversion include windows, staircase, doors, bathroom, flooring and roofing.
The tables below summarise the average costs of different supply materials, distinguishing between standard and premium quality. Let's explore them:
Windows
| Window type | Quality | Average cost for 1 window |
|---|---|---|
| Small, vinyl, double glazed | Standard | £1,500 |
| Large, wooden, double glazed | Premium | £3,000 |
- Opt for vinyl or composite windows over wood to save on cost. Ensure double or triple glazing for more energy efficiency.
- Smaller window sizes are more economical yet still let in light. Consider adding more smaller windows rather than fewer large ones.
Flooring
| Flooring type | Quality | Average cost per 30 m2 |
|---|---|---|
| Laminate throughout | Standard | £1,000 |
| Hardwood flooring | Premium | £3,000 |
- Laminate flooring has a low upfront cost but higher maintenance than wood. If you want to ensure the longevity of the floor perhaps investing in wood flooring can be the right choice, reducing potential costs down the road.
- Carpet offers a lower initial purchase price and installation cost than most hard flooring types. Carpet is often less expensive per square metre, and installation is less labour-intensive.
Staircase
| Type | Quality | Average cost |
|---|---|---|
| Straight, pine | Standard | £1,000 |
| Spiral, oak | Premium | £3,000 |
- Pine stands out as the most budget-friendly yet high-quality wood option for stairs, while oak and exotic woods incur additional costs for a luxurious aesthetic.
- Straight or L-shaped staircases are the most budget-friendly. Avoid more complex spirals or curved steps. However, not all loft conversions will be able to do these types of stairs due to the size and shape of the below floor.
Insulation
| Type | Quality | Average cost |
|---|---|---|
| 100m2 rigid boards | Standard | £500 |
| 100m2 loft roll | Premium (High efficiency) | £1,500 |
- Typically rolls are the cheapest option to meet building regulation minimums. Add rigid boards for higher efficiency.
- When considering insulation, it's good to know that insulating your roof is absolutely essential, while insulating walls and floors is recommended. So if you want to cut costs you can opt for insulating your roof only. But keep in mind that you would get the most out of your insulation if you do it all around.
Internal doors
| Type | Quality | Average cost |
|---|---|---|
| Internal hollow core | Standard | £100 |
| Internal oak panelled | Premium | £500 |
- Hollow-core wooden doors provide an inexpensive, clean look. Plus, you can personalise your doors by painting them, which usually doesn't cost much.
- Simple 4-panel or 6-panel styles cost less than intricate door designs or glass elements.
Roofing
| Type | Quality | Average cost |
|---|---|---|
| Concrete tiles | Standard | £3,000 |
| Natural slate | Premium | £6,000 |
- To cut costs, you can look into recycled, eco-friendly roofing supply options. Materials like recycled polymer roof tiles or reclaimed slate shingles cost less while diverting waste.
- Check local salvage yards and used building supply stores first before buying new materials.
Bathroom
| Type | Quality | Average cost |
|---|---|---|
| Basic suite, ceramic tiling | Standard | £2,000 |
| Luxury suite, stone tiling | Premium | £5,000 |
- Ceramic tiling and acrylic suite finishes are the most budget bathroom options. Limit lavish materials.
- Smaller showers take less time to build and require less supply of materials. This makes them more economically beneficial compared to large walk-in types.
Tradesman costs
Hiring professional tradespeople ensures the dormer is built according to rules and regulations. In addition, professionals can ensure that the work is done and won't need to be redone again in the near future.
Let’s explore the costs associated with these professionals:
| Contractor | Payment per day |
|---|---|
| Builder | £150–£200 |
| Electrician | £200–£250 |
| Plumber | £150–£200 |
| Roofer | £100–£150 |
Complex projects also require an architect for planning. The architects in the UK usually charge £800–£1,000 for overall planning and drawings.
Here are some savvy tips for getting a better quote from contractors and other tradesmen:
- Supply all non-speciality materials yourself (with advice) rather than builder markups.
- Schedule work during slower seasons for better availability and cheaper trade rates.
- Consider volunteering 1-2 weeks of DIY labour in exchange for a discount from builders
Ready to start your conversion? Skip the hassle of looking for quotes— simply fill out our quick form to receive up to 3 free quotes from trusted local specialists. Click below to get started!
- Describe your needs
- Get free quotes
- Choose the best offer
Other costs
Not all loft conversions will go according to plan, hidden and unexpected costs can arise. Here are potential hidden costs that can appear with dormer conversions:
- Structural issues: Unforeseen problems like rotten joists or unstable roof structures may cost £2,000–£5,000 to repair.
- Scaffolding hire: For safe exterior access, scaffolding typically costs £500–£1,500 to erect and dismantle. As a rough guide, you can expect to pay from £18 to £24 per m2 per day, depending on the length and complexity of the scaffolding project. Longer rental periods will increase the price, though some companies offer reduced rates for extended hires.
- Waste removal: Specialist waste carriage services remove construction debris, with costs starting at around £500. Multiple trips may be needed for larger volumes of waste.
- Building regulations: Meeting council requirements may necessitate added expenses for things like window specs, energy efficiency, fireproofing etc. Budget £1,000–£3,000.
- VAT: Value Added Tax around 20% often gets overlooked when budgeting. Remember to factor this into all building work costs.
- Contingency funds: We advise keeping 10–15% of the total budget as a contingency for unexpected overages. This acts as a buffer for last-minute additions.
- Planning permission: May be needed if the dormer roof extends more than 0.3 metres above the existing roof ridge or if its width is over 50% of the original roof width. It is also required for historical areas or conservation areas. Always check with local authorities to confirm if permission is required. Fees typically range from £150–£500.
- Party wall agreements: These apply if the dormer extends onto or affects a shared wall. Typically semi-detached and terraced houses need them, detached homes usually do not. Party wall surveyors cost anywhere between £600–£1000.
- Building regulations: Loft conversions in the UK must comply with several key aspects of the Building Regulations. A building control surveyor should inspect and approve the dormer conversion. Their fees range from £500 to £1000.
Careful planning reduces unexpected costs, but budgeting an extra 10–15% covers any unknowns.
How to reduce your dormer loft conversion cost
Dormer loft conversions require significant investment. However, if you have a limited budget, there are ways to reduce costs.
Strategies and tips for reducing costs:
- Hire an architect: Investing in an architect's expertise can lead to significant cost savings during the design phase, potentially avoiding expensive modifications later. By allocating a budget of £800–£1200 for their fees, you can ensure your plans are optimised for efficiency and economy.
- Use reclaimed materials: Second-hand bricks, beams, doors and fixtures cut supply costs over new ones. Check salvage yards and reuse centres.
- Choose affordable finishes: Opt for budget-friendly laminate flooring, vinyl windows and medium-grade insulation. Avoid premium materials. We recommend shopping during slower building seasons for cheaper prices and discounts.
- DIY demolition and tidying: Doing your own interior prep work saves on builder labour costs. You can do tidying, painting, installing insulation, laying laminate floors, and decorating, which are manageable for those willing to invest the time and effort.
- Shop around for tradespeople: Compare quotes from several reputable builders and electricians. Pick the best value. We recommend planning your project for off-peak seasons. It can lead to better availability of tradespeople and potentially lower rates, as demand for their services decreases.
- Split work over phases: Complete the structural and roof work first, leaving finishes for later budget availability.
With careful planning and cost-saving materials, loft conversions can be achievable even on limited funds. Prioritise essential structural work first and get creative to fit the budget.
How to finance your dormer conversion
Dormer loft conversion can be a very expensive project. Yet, there are ways to finance the conversion fully or partly. If you need assistance funding a dormer conversion, there are several financing options to explore:
- Home improvement loans: Banks offer loans specifically for renovations, with extended repayment terms from 5–15 years. Interest rates are around 5–10%.
- Remortgaging: By remortgaging, you might be able to release equity in your home, allowing you to add the cost of the project to your existing mortgage. This option can provide a substantial sum for your conversion, depending on the equity available in your property.
- Secured loans: Use your home as collateral to get a lump sum at a lower interest rate. It's crucial to understand the risks involved with this option. If you fail to meet the repayment terms, your home may be at risk of repossession. It's essential to consider your ability to maintain loan payments over time before proceeding with a secured loan.
- 0% credit cards: For short-term financing, some credit cards offer a 0% interest rate for periods ranging from 12 to 18 months. This option can be cost-effective if you can repay the borrowed amount within the interest-free period.
-
Local authority grants: Some councils grant low-income households essential home improvements. These range from £5,000 to £15,000 and can be used for things like insulation, heating, and structural repairs.
Eligibility for these grants often hinges on several criteria, including your financial situation, the property's condition, and the potential for the renovation to improve living conditions.
For instance, grants may be more readily available to those aiming to enhance energy efficiency or to make homes more accessible for residents with disabilities.
We advise to contact your local council directly to inquire about available grants, eligibility requirements, and the application process, ensuring you have all the necessary information to proceed. - Disabled facilities grants: These fund adaptations like stairlifts, ramps and home modifications to allow disabled residents to live safely and independently. Grants cover £5,000 to £30,000 based on income and are administered by local councils.
- VAT relief: It’s good to know that VAT relief for disability home adaptations is zero-rated in the UK, with no monetary limit.
-
Charitable grants: Organisations like Turn2Us and Charis Grants provide small renovation grants of £2,000–£5,000 for disadvantaged groups. Age UK also offers insulation grants for the elderly.
With a thoughtful financing strategy tailored to your situation, a dormer conversion can work even on a tight budget. Consider all options to make your loft dreams a reality.
Compare dormer loft conversion quotes
After researching estimated costs, the next step is obtaining custom quotes for loft conversion tailored to your specific property. While this article provides general figures, nothing compares to quotes from builders in your local community.
This is why you should compare quotes:
- Prices are based on your home’s unique layout, roof structure, access and other factors thus, they are more accurate.
- You can compare costs for the same scope of work
- Leverage to negotiate pricing and packages
- Custom options like materials, window styles and finishes
- Tailored project timelines based on complexity
- Industry knowledge on best practices for your situation
Simplify getting quotes by using our free services. We provide free access to 4 detailed quotes from qualified local loft conversion specialists for your specific project.
With WhatCost, you can compare detailed bids side-by-side. There is no obligation to pick any quotes.
With expertise and quotes tailored to your property, you can confidently plan and finance your dormer conversion. This investment will enhance your home and lifestyle for years to come.
- Describe your needs
- Get free quotes
- Choose the best offer
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