Loft Conversions: Dormer, Hip to Gable, Mansard and Rooflight Lofts

Dormer
Hip to gable
Mansard
Rooflight

Finished loft conversion by 5K Construction

%Up to 24%added value

✓500+projects completed

10+years building experience
500+projects completed
Up to 24%added value (Nationwide, October 2025)
6types of loft conversion

Most homeowners who ask us about loft conversions have the same problem: the family has outgrown the house, but moving means stamp duty, legal fees and leaving a street they like. A loft conversion, sometimes called an attic conversion or loft extension, turns the unused roof space above your bedrooms into a bedroom, en-suite or home office, without losing any garden.

In the West Midlands, a loft conversion typically costs from about £20,500 for a small rooflight conversion to £82,000 for a large mansard, with the average around £41,000 (MyJobQuote, Birmingham prices, 2026). Many dormer and hip to gable conversions fall under permitted development and need no planning application, but every loft conversion needs building regulations approval.

5K Construction has more than 10 years of building experience and 500+ completed projects across Wolverhampton and the West Midlands. One team handles your loft from the first site survey to the building control completion certificate.

Call 07505 937668 Book a site survey

Loft conversion bedroom built by 5K Construction

01Suitability

Is Your Loft Suitable for a Conversion?

Many houses with a pitched roof can take a loft conversion of some kind. The question is which type, and how much structural work it needs. Four checks decide it, and we cover all of them at the site survey. A steeper roof pitch generally leaves more usable headroom to work with.

Check	What to look for	Why it matters
Head height	At least 2.2m at the highest point of the roof space	Below this, you may need a dormer, a mansard or a lowered ceiling to get usable headroom
Roof structure	A traditional cut roof (rafters and purlins) or a trussed roof (W-shaped timber trusses)	Cut roofs are the simplest to convert; trussed rafters must not be altered without a structural engineer's design
Floor build-up	The new floor usually sits about 200mm above the existing ceiling joists	That lost height must still leave enough headroom in the new room
Space for the staircase	2m of headroom over the stairs, or 1.9m at the centre and 1.8m at the edge where building control agrees	The stair position often decides the room layout on both floors

The head height guide comes from loft specialist guidance on suitability. The roof structure, floor and stair figures come from Warwick District Council building control guidance.

Practitioner insight: Do not judge a loft by how it feels with the hatch open. Water tanks, chimney breasts and old storage boarding hide the real dimensions. A tape measure from the ceiling joists to the ridge tells you far more than a look around with a torch.

Blueprint: headroom and floor build-up

New floor build-up: about 200mm above the existing ceiling joists.
Existing ceiling joists of the room below.

Loft room with full headroom after conversion

026 loft types

Types of Loft Conversion We Build

The right loft conversion depends on your roof shape, the head height you have and how much floor space you need. Prices below are 2026 Birmingham ranges for a 30m² and a 50m² loft from MyJobQuote, the closest published regional benchmark for the West Midlands.

Side view

Dormer Loft Conversion

A dormer is a box-shaped roof extension built out from the rear roof slope, with vertical walls and a flat roof. It is the most common way to gain full standing headroom and floor space, and a full-width rear dormer suits many terraced and semi-detached houses. Many rear dormers fall under permitted development, within the 40 or 50 cubic metre allowance.

Expect£36,000 to £51,500 for a 30m² loft and £46,500 to £72,000 for 50m².

6 to 8 weeks on site

Flank view

Hip to Gable Loft Conversion

Semi-detached and detached houses often have a hipped roof, where the side slopes inwards and limits the space. A hip to gable conversion rebuilds that sloping side as a vertical gable wall, and it is often combined with a rear dormer for the largest room. The permitted development eaves conditions do not apply to the hip to gable part of the work.

Expect£46,500 to £61,500 for 30m² and £56,500 to £72,000 for 50m².

6 to 8 weeks on site

Side view

Mansard Loft Conversion

A mansard rebuilds the rear roof slope at a near-vertical angle with a flat top, creating almost a full extra storey. It gives the most space of any loft type, but it changes the roof profile, so it often needs full planning permission.

Expect£55,000 to £70,000 for 30m² and £67,000 to £82,000 for 50m².

8 to 10 weeks on site

Side view

Rooflight (Velux) Loft Conversion

A rooflight conversion keeps the existing roof shape and adds roof windows, such as Velux windows, set into the slope. It needs the least structural work, so it is the quickest and most affordable option, but only where the loft already has enough head height. Rooflights are usually permitted development if they do not project more than 150mm beyond the roof slope.

Expect£20,500 to £31,000 for 30m² and £26,000 to £41,000 for 50m².

4 to 6 weeks on site

Rear view

L-Shaped Dormer

An L-shaped dormer joins two dormers: one on the main roof and one on the rear outrigger roof. It suits period terraced houses with a rear back addition and can create two bedrooms or a bedroom with an en-suite.

Expect£51,500 to £61,500 for 30m² and £56,500 to £72,000 for 50m².

Side view

Bungalow Loft Conversion

A bungalow loft conversion adds bedrooms upstairs inside the existing roof. The wide footprint of a bungalow often gives a generous floor area, and dormers or rooflights bring in light and headroom. Habitable rooms on the new floor of a converted bungalow need an escape window.

ExpectThe average bungalow loft conversion costs around £75,000 (Checkatrade figures via HomeOwners Alliance, 2026).

In each blueprint the gold area shows the extra space the conversion adds.

Dormer loft conversion by 5K Construction

Loft conversion interior by 5K Construction

03Ideas

Loft Conversion Ideas: How to Use Your New Space

Decide how you will use the loft before the design is drawn, because the room's purpose changes where the stairs, windows and plumbing go.

Main bedroom with en-suite

Full headroom over the bed and the door; the en-suite placed above an existing bathroom to keep drainage simple

Best suited: Dormer or hip to gable

Two children's bedrooms

Two separate rooms of usable size, each with its own window

Best suited: L-shaped dormer or mansard

Home office

Roof windows over the desk for daylight; sockets and data cabling planned at first fix

Best suited: Rooflight or dormer

Guest suite

A double bedroom with a shower room, away from the main living areas

Best suited: Dormer

Playroom or snug

Open floor space with built-in storage under the low eaves

Best suited: Rooflight or dormer

Practitioner insight: The low space under the roof slope, where you cannot stand, is ideal for built-in eaves storage. Planning it into the design from the start costs far less than adding cupboards later, and it keeps the main room clear.

04Costs 2026

How Much Does a Loft Conversion Cost in 2026?

The UK average loft conversion costs about £40,000, and Birmingham is close to that at about £41,000 (MyJobQuote, 2026). Your price depends mainly on the type of conversion and the floor area.

Price ranges at a glance

30m² loft50m² loft

Rooflight (Velux)

Dormer

Hip to gable

L-shaped dormer

Mansard

Shell only

£0£30k£60k£90k

Type of loft conversion	30m² loft	50m² loft	Typical time on site
Rooflight (Velux)	£20,500 to £31,000	£26,000 to £41,000	4 to 6 weeks
Dormer	£36,000 to £51,500	£46,500 to £72,000	6 to 8 weeks
Hip to gable	£46,500 to £61,500	£56,500 to £72,000	6 to 8 weeks
L-shaped dormer	£51,500 to £61,500	£56,500 to £72,000	—
Mansard	£55,000 to £70,000	£67,000 to £82,000	8 to 10 weeks
Shell only (structure, no finishing)	£20,500 to £41,000	£31,000 to £56,500	—

Source: MyJobQuote, Birmingham loft conversion prices, updated September 2026.

What pushes the price up or down

Size and type: a mansard or hip to gable needs more structural work than a rooflight conversion.
Steel beams and floor joists: most conversions need new joists and rolled steel joists (RSJs) sized by a structural engineer.
An en-suite: adds plumbing, drainage, waterproofing and an extract fan.
The staircase: a new stair, fire doors and the protected stairway it needs.
Windows and finish: roof windows, a Juliet balcony, flooring and the standard of joinery.

Completed loft conversion with roof windows

Fees and costs to budget for on top of the build

Item	Typical cost	Source
Householder planning application (England, from 1 April 2026)	£548	Planning fee schedule, 1 April 2026
Lawful Development Certificate (proposed development)	Half the planning fee: £274	Planning fee schedule, 1 April 2026
Architectural drawings and design	£2,000 to £5,000	PlanWatch, 2026
Structural engineer's calculations	£600 to £1,500	PlanWatch, 2026
Party wall agreement	£1,000 to £2,500 per neighbour	PlanWatch, 2026

VAT: loft conversions are charged at the standard 20% rate, and many contractors quote prices before VAT, so always check which figure you are comparing (PlanWatch, 2026).
Contingency: keep 15% to 25% of the build cost in reserve, towards the top of that range for older houses and party wall complications (PlanWatch, 2026).

Practitioner insight: When you compare quotes, line them up item by item: structural steel, staircase, fire doors, windows, en-suite, flooring, decoration and VAT. Two quotes with the same total can cover very different amounts of work.

05Value

Does a Loft Conversion Add Value?

Yes. A loft conversion is one of the improvements that adds the most value to a house, because it adds a bedroom without reducing your garden or ground floor space. Nationwide Building Society research published in October 2025 found:

Up to 24%

Loft conversion or extension adding a double bedroom and bathroom to a three-bedroom, one-bathroom house

Source: Nationwide Building Society, October 2025

13%

Adding a double bedroom to a two-bedroom house

Source: Nationwide Building Society, October 2025

10%

Taking a three-bedroom house to four bedrooms

Source: Nationwide Building Society, October 2025

~5%

Adding 10% more floor space

Source: Nationwide Building Society, October 2025

The biggest gain comes from adding both a bedroom and a bathroom, which is why many homeowners plan an en-suite into the loft from the start. Value also depends on build quality: a cramped stair, low headroom or a missing completion certificate can cost you when you sell.

Practitioner insight: If resale value matters, plan the loft as a proper bedroom: full standing headroom over the bed and the door, a fixed staircase rather than a ladder, and an en-suite where the drainage allows. Buyers and their surveyors judge a loft room on exactly these points.

06Planning

Do You Need Planning Permission for a Loft Conversion?

Often not. Many loft conversions in houses are permitted development, which means they can go ahead without a planning application. Mansards, front-facing dormers and lofts on designated land usually do need planning permission.

Permitted development conditions for a loft conversion

A loft conversion is permitted development only when it meets all of the Planning Portal conditions. The main ones are (Planning Portal):

The property is a house, not a flat or a building containing flats.
The house is not on designated land, such as a conservation area, a National Park or an Area of Outstanding Natural Beauty.
The added roof space, including any earlier roof extension, is no more than 40 cubic metres for a terraced house or 50 cubic metres for a detached or semi-detached house.
No part of the roof extension is higher than the existing roof.
Nothing extends beyond the plane of the existing roof slope on the principal elevation facing a highway.
Materials look similar to the existing house.
There are no verandas, balconies or raised platforms. A Juliet balcony with no platform is normally acceptable.
Side-facing windows are obscure-glazed, and any opening part is at least 1.7m above the floor.
The original eaves are kept, and the roof extension is set back, as far as practicable, at least 20cm from the eaves. This does not apply to the hip to gable part of a conversion.
The roof extension does not overhang the outer face of the house wall.

The work also cannot install, alter or replace a chimney, flue or soil and vent pipe, and houses created or extended upwards under other permitted development rights are excluded.

Rooflights that keep the roof shape are assessed separately and are usually permitted development if they project no more than 150mm beyond the roof slope and sit no higher than the highest part of the roof (Class C self-assessment guidance).

Get a Lawful Development Certificate

Even when a loft conversion is permitted development, we recommend a Lawful Development Certificate from your local planning authority. It costs £274 in England from 1 April 2026 (half the £548 householder planning fee) and gives you written proof that the work was lawful, which buyers' solicitors often ask for when you sell.

Article 4 directions and conservation areas

An Article 4 direction removes some permitted development rights on specific streets. In Wolverhampton, for example, City of Wolverhampton Council has Article 4 directions on 13 of the city's 31 conservation areas, so a dormer that is permitted development on one street may need planning permission on the next. We check your address before any design work starts.

Party wall notices

In a terraced or semi-detached house, the new steel beams often bear into the party wall you share with your neighbour. Under the Party Wall etc. Act 1996, you must give your neighbour notice between 2 months and a year before work starts.

House with a rear dormer loft conversion

07Building regulations

Building Regulations for Loft Conversions

Every loft conversion that creates habitable loft space needs building regulations approval, whether or not it needs planning permission. Building control inspects the work at key stages and issues a completion certificate at the end. Without that certificate, you may struggle to sell or remortgage.

Approved Document	What it covers in a loft conversion
Part A: Structure	New floor joists and steel beams sized by a structural engineer, so the old ceiling joists are not overloaded
Part B: Fire safety	A protected stairway, fire doors and interlinked smoke alarms so everyone can get out safely
Part E: Sound	Sound-deadening insulation in the new floor and, in attached houses, an upgraded party wall
Part F: Ventilation	Opening windows or roof windows plus trickle vents, and extract fans in any en-suite
Part K: Stairs and guarding	Stair pitch, rise, going, headroom, handrails and balustrades
Part L: Energy efficiency	High-performance insulation to the roof, walls and dormer, and efficient double glazing
Part P: Electrical safety	New circuits installed, tested and certified to the wiring regulations

Fire safety: the protected stairway

When a loft turns a two-storey house into three storeys, the stair becomes your escape route. Building control guidance requires (Warwick District Council; Eden District Council):

Half-hour (FD20) fire doors on every habitable room that opens onto the stair.
A protected stairway that ends at a hall with a direct exit to outside.
Mains-powered, interlinked smoke alarms on every floor.
An escape window in habitable rooms where required, such as a converted bungalow, with a clear opening of at least 0.33m², at least 450mm wide, and no more than 1100mm above the floor.

Stairs

Maximum pitch of 42 degrees, with a rise of no more than 220mm and a going of at least 220mm per step.
Headroom of 2m over the stair, or 1.9m at the centre and 1.8m at the edge where the loft roof slope makes 2m impossible.
Handrails and balustrades are at least 900mm high, with no gaps over 100mm.
Alternating tread stairs are a last resort, allowed only for a single habitable room.

Insulation, sound and ventilation

The roof is insulated with high-performance boards between and below the rafters, with a ventilated gap above to stop condensation. The new floor gets around 100mm of sound-deadening quilt. Habitable rooms need an opening window or roof window equal to at least one-twentieth of the floor area, plus a trickle vent.

Blueprint: the protected stairway

Protected stairway with FD20 fire doors on every habitable room that opens onto it.
Interlinked smoke alarms on every floor.
Direct exit to outside at the foot of the stair.

New loft staircase and landing built to building regulations

Practitioner insight: The staircase is where most loft designs succeed or fail. Plan it before anything else, because it fixes the layout of the loft and takes space from the landing below. Moving it after the steels are in costs time and money.

08Avoid these

7 Loft Conversion Mistakes to Avoid

Most loft conversion problems start before anyone climbs the scaffolding. These are the mistakes that cost homeowners the most time and money.

Measuring head height from the loft floor as it is.The new floor usually sits about 200mm higher than the existing ceiling joists, so measure with that in mind.

Leaving the staircase until last.The stair decides the loft layout and takes space from the landing below. Fix its position first.

Cutting trussed rafters without a structural engineer.Trussed roofs must not be altered without a structural engineer's design, or the whole roof can be weakened.

Skipping the Lawful Development Certificate.Permitted development work with no certificate can raise questions from a buyer's solicitor when you sell.

Serving party wall notices too late.Notice must be given at least 2 months before work starts, so a late notice delays your start date.

Ignoring ventilation.Without a ventilated gap above the insulation, condensation can form in the roof.

Budgeting for the quote only.Keep a contingency of 15% to 25% and check whether the quote includes VAT.

Keep it safe: keep your building control completion certificate safe at the end. Buyers, lenders and their surveyors will ask for it.

0912 steps

Our Loft Conversion Process, From Site Survey to Completion Certificate

Site survey.We measure your head height, check the roof structure (cut roof or truss roof), look at the stair position and talk through how you want to use the room.
Measured survey and design.Architectural drawings set out the layout, windows, staircase and en-suite, and show which type of loft conversion fits your roof.
Structural calculations.A structural engineer sizes the steel beams, floor joists and any changes to the rafters and purlins.
Written quote and schedule.You receive a written quote listing what is included and excluded, with VAT shown, and a planned start date.
Planning route.We confirm whether your loft is permitted development or needs a planning application, and apply for a Lawful Development Certificate where it is permitted development.
Party wall notices.Where steels bear into a shared wall, notices go to your neighbours at least 2 months before work starts.
Building control application.Submitted before work begins, so inspections can be booked at each stage.
Scaffolding and structure.Scaffolding goes up, the roof is opened, and the steel beams, floor joists and dormer or gable walls are built, then made weathertight.
First fix.Electrics, plumbing, insulation and stud walls go in, ready for inspection.
Staircase and fire protection.The stair opening is formed, the new staircase fitted, and fire doors and interlinked smoke alarms installed.
Plastering and second fix.Plasterboard, skim, sockets, lights, sanitaryware, joinery and decoration.
Sign-off and handover.Building control carries out its final inspection and issues the completion certificate. We finish snagging and hand over your electrical certificate and product guarantees.

How long does a loft conversion take?

Stage	Typical time	Source
Design, structural calculations and approvals	3 to 6 months before work starts	PlanWatch, 2026
Rooflight conversion on site	4 to 6 weeks	MyJobQuote, 2026
Dormer or hip to gable on site	6 to 8 weeks	MyJobQuote, 2026
Mansard on site	8 to 10 weeks	MyJobQuote, 2026

Most families stay at home during a loft conversion, because the early structural work is reached from the scaffolding. The most disruptive stage is when the staircase opening is cut into the landing below.

Homeowner tip: Agree stage payments linked to finished work, such as weathertight, first fix and completion, rather than paying most of the cost upfront.

10Checklist

How to Prepare for Your Loft Conversion

A little preparation before work starts keeps your project on schedule and your household calm.

Clear the loft. Empty stored items and decide where they will go during and after the build.
Decide how you will use the room. Bedroom, en-suite, office or playroom, before the drawings start.
Talk to your neighbours early. A friendly conversation before the party wall notice makes consent easier.
Set your full budget. Build cost, VAT, professional fees and a 15% to 25% contingency.
Tell your home insurer. Most policies need to know about major building work before it starts.
Plan access. Agree where the scaffolding, materials and any skip will go; a skip on the road needs a council permit.
Protect the floor below. Clear the landing and the bedroom under the new staircase opening before that stage starts.

Prepared loft space ready for conversion

11Why 5K

Why Choose 5K Construction for Your Loft Conversion?

A loft conversion touches the structure, the roof, the stairs and the fire safety of your whole house. That is why the builder you choose matters more than the price on the first page of the quote.

10+ years and 500+ projects.Lofts, extensions, kitchens, bathrooms and full renovations across Wolverhampton and the West Midlands.

Survey first, price second.We measure your loft and check the roof structure before we quote, so the price reflects your actual house.

Approvals sorted before work starts.We confirm the planning route and arrange building control, so nothing stops the job halfway through.

One team, one point of contact.The structure, the en-suite, the electrics and the decoration are coordinated by one team.

A clear written quote.Inclusions, exclusions and VAT are set out in writing, so you can compare like for like.

Local and easy to reach.Based at 40A Oaklands Rd, Wolverhampton WV3 0DS, and open seven days a week.

Accountable.Our insurance and trade accreditations and our complaints procedure are published in full. Learn more about our Wolverhampton building company.

12Our work

Recent Loft Conversions by 5K Construction

Every loft is different, so the best guide to what yours could look like is a finished project on a similar house.

Loft conversion by 5K Construction — Loft conversion

Loft conversion bedroom by 5K Construction — Loft bedroom

New loft room by 5K Construction — New loft room

View our full building project portfolio

13Related

Services Often Combined With a Loft Conversion

Bathroom InstallationAn en-suite in the loft adds the most value, and our bathroom team plans the waterproofing, drainage and extraction.Bathroom Installation → House ExtensionsWhen the loft alone is not enough, a ground floor extension can be planned alongside it.House Extensions → Renovation and RefurbishmentA loft is a good moment to rewire, replaster or reconfigure the floor below.Renovation and Refurbishment → Home ImprovementsPlastering, flooring, joinery and decorating to finish the new room.Home Improvements →

14Areas

Loft Conversions Across the West Midlands and Beyond

We build loft conversions from our Wolverhampton base and across the towns below.

Builders in Wolverhampton Builders in Shrewsbury Builders in Worcester Builders in Coventry Builders in Stoke-on-Trent Builders in Nuneaton Builders in Burton upon Trent Builders in Redditch Builders in Market Drayton Builders in Droitwich Spa Builders in Ludlow

See all areas we cover

15FAQs

Loft Conversion FAQs

Do I need planning permission for a loft conversion?

Often not. Many loft conversions are permitted development if the added roof space stays within 40 cubic metres for a terraced house or 50 cubic metres for a detached or semi-detached house, and other conditions are met. Mansards, front dormers, flats and homes on designated land usually need planning permission. A Lawful Development Certificate confirms your position.

How much does a loft conversion cost in 2026?

A loft conversion in the West Midlands typically costs from about £20,500 for a small rooflight conversion to £82,000 for a large mansard, according to MyJobQuote's 2026 Birmingham prices. A dormer usually costs £36,000 to £72,000. Add VAT at 20%, professional fees and a 15% to 25% contingency to your budget.

How long does a loft conversion take?

Most loft conversions take 4 to 10 weeks on site: about 4 to 6 weeks for a rooflight conversion, 6 to 8 weeks for a dormer or hip to gable, and 8 to 10 weeks for a mansard. Allow 3 to 6 months beforehand for design, structural calculations and approvals.

What is the minimum head height for a loft conversion?

A good starting guide is at least 2.2m of head height at the highest point of the roof space. The new floor usually sits about 200mm above the existing ceiling joists, which reduces the usable height. If your loft is lower, a dormer, mansard or lowered ceiling may still make a conversion possible.

Does a loft conversion need building regulations approval?

Yes. Every loft conversion that creates a habitable room needs building regulations approval, even when planning permission is not required. Building control checks the structure, fire safety, stairs, insulation, ventilation and electrics, then issues a completion certificate. Keep that certificate, because buyers and lenders will ask for it when you sell or remortgage.

Does a loft conversion add value to a house?

Yes. Nationwide Building Society research published in October 2025 found that a loft conversion or extension adding a double bedroom and bathroom can raise the value of a three-bedroom, one-bathroom house by up to 24%. Adding an en-suite to the loft usually gives a bigger uplift than a bedroom alone.

Can I stay in my house during a loft conversion?

Most families stay at home during a loft conversion. The early structural work is reached from scaffolding, so daily life downstairs carries on. The most disruptive stage is when the staircase opening is cut into the landing below, and dust sheets and temporary protection keep the rest of the house clean.

Do I need a party wall agreement for a loft conversion?

Usually, if you live in a terraced or semi-detached house. Steel beams for a loft conversion often bear into the party wall you share with your neighbour, which falls under the Party Wall etc. Act 1996. You must give notice between 2 months and a year before work starts, and your neighbour can consent or appoint a surveyor.

Which type of loft conversion is cheapest?

A rooflight conversion, often called a Velux conversion, is usually the cheapest because it keeps the existing roof shape and only adds roof windows. In the West Midlands it costs from about £20,500 for a 30 square metre loft. It only works where the loft already has enough head height.

Bright loft room after conversion by 5K Construction

Start Your Loft Conversion With a Site Survey

The quickest way to know what your loft can become is to have it measured. We will check your head height, roof structure and stair position, tell you which type of loft conversion suits your house and whether it needs planning permission, and follow up with a written quote.

Call 07505 937668 Book a site survey

5K Construction40A Oaklands Rd, Wolverhampton WV3 0DS
Phone: 07505 937668
Email: info@5kconstruction.co.uk
Opening hours: Monday to Friday 8am to 6pm, Saturday 8am to 2pm, Sunday 9am to 1pm