Loft conversion price guide

How much does a loft conversion cost? If you know your attic space is suitable for a loft conversion, you’re probably wondering how much it’s going to set you back. A loft conversion can add thousands to the value of your home and gives you a versatile space to use with your family.

The average cost of a loft conversion is £40,000. It’s likely to take up to 12 weeks. But costs vary depending on the type of roof you have, your location and how big you’d like your conversion to be - so make sure you get a range of quotes from reputable tradespeople to ensure you’re paying a fair price.

In this guide, we’ll help you to get an idea of how much you’ll pay for a loft conversion by breaking it down into sections:

1. Types of loft conversion

2. Material costs for loft conversions

3. Will I need planning permission?

4. Cost example of a loft conversion

5. How long does a loft conversion take?

Types of loft conversion

How much a loft conversion costs will depend on the type of conversion you’d like. There are a few different types to consider:

Roof light conversion

A roof light, or Velux, conversion is usually the most cost-effective type of loft conversion. It’s also the least disruptive type as it involves adding a skylight window (the best-known brand is Velux), laying a suitable floor and putting in a staircase for access. This type of loft conversion is perfect if you want to use the space as a home office or separate living area for older children. You can find a builder to fit a Velux roof for around £30,000.

A roof light conversion is likely to take between 4 and 7 weeks, depending on the size of your loft.

Dormer

A dormer loft conversion is the most common type of loft conversion. It involves a builder extending your existing roof with vertical walls, so you get more floor space and can add more windows. Most properties with sloping roofs are suitable for a dormer conversion, but you should always check with a structural engineer or architect if you’re unsure.

Dormer conversions are ideal for creating an extra bedroom with an ensuite. The extra space and additional windows allows for more light to come in, so the room will feel even larger.

Expect a dormer loft conversion to take between 6 and 9 weeks.

Hip to gable conversion

A hip to gable loft conversion involves replacing one side of your sloping, hipped roof with a vertical end wall (a gable end), which increases the amount of space you have in your loft. Hipped roofs tend to have limited floor space so having a hip to gable conversion will help you to fit in a staircase alongside your living space without it feeling cramped.

However, it’s worth bearing in mind that hip to gable loft extensions are classed as major roof alterations, so you’ll need to apply for planning permission. You can also only have a hip to gable conversion if your house is detached or semi-detached. They generally take between 6 and 9 weeks to complete.

Mansard loft conversion

Mansard loft conversions are typically the most expensive type of conversion. They have sloping walls and a flat roof, making them a versatile type of attic extension that can work for lots of properties. You can also ask an architect to design a mansard extension to match your home so it doesn’t look out of place.

Since you’ll need to change the roof a lot, a mansard loft conversion is the most expensive type and you’ll also need to apply for planning permission before any work can begin.

Mansard loft conversions take anywhere between 8 and 11 weeks to complete.

Bungalow loft conversions

It’s not uncommon for bungalow owners to decide to convert their lofts since there is so much space in the roof. You could create extra space for bedrooms, living areas and bathrooms - whatever your family needs!

Since bungalow lofts are larger, the average cost of a conversion is higher than for two-storey homes. They also take longer to finish - around 10 to 12 weeks.

Material costs for loft conversions

Since you’re creating a whole extra room for your house, there are a lot of material costs to think about. These include:

• Windows Costs
• Flooring Costs
• Stairs Costs
• Lighting Costs
• Heating Costs
• Insulation Costs

Note: due to Covid-19 lockdowns and Brexit shortages, material prices are currently higher than usual. You might find that you also have a longer wait for materials to arrive, so it’s worth factoring this into the time your loft conversion takes.

Loft conversion window costs

If you want to use your new attic conversion as a proper room, you’ll want plenty of light coming in through windows. Speak to your builder or architect about the amount of windows they recommend you should have. The cost of your windows will depend on the type you’ll need. If you’re having a dormer loft conversion, you’ll want specific dormer windows, but you may want roof lights for other types of loft extension.

Roof lights are often referred to as Velux windows, but this is just one brand. These windows fit into your roof and can be manually controlled or operated using a remote.

Loft conversion flooring costs

Flooring is one of the most important costs to consider when it comes to furnishing your loft conversion. What kind of style do you want? Would you like real wood, laminate or carpet? These days, there are lots of options out there and they don’t have to break the bank.

Here’s a quick summary of the costs of different types of flooring:

Costs of stairs for your loft conversion

You’ll need to consider the cost of your stairs if you want to access your loft conversion! Do you want to go for a traditional, understated look or a more modern aesthetic? Whatever you choose, there’s a cost involved and it’s one you don’t want to scrimp on for safety as well as style.

Costs of lighting for your loft conversion

The angle of the roof can make loft conversions quite dark, so you’ll want to consider lighting carefully. When you furnish your room, you might want to add table or floor lamps, but we’ll focus on the lighting you’d need an electrician to wire in for you.

You’ll need to decide whether you’re happy with standard ceiling lights, like spotlights and pendants, or whether you’d like to splash out and get smart lighting that you can control with your smartphone.

Loft conversion heating costs

You’ll need to ensure you can heat your loft conversion efficiently if you want to use it as an extra living space. These days, lots of people go for underfloor heating since you can power it using solar panels, but you’ll need to have this installed before your floor is laid. Many people opt to add radiators to their current gas central heating system.

Make sure you check that your current boiler will be able to cope with additional radiators - otherwise you may need to factor in the cost of a new boiler too.

Loft conversion insulation costs

You’ll need to consider the cost of insulation for your loft extension as you want to make sure you don’t lose too much heat through the roof and walls. How much it sets you back will depend on the type of insulation you choose.

Will I need planning permission for my loft conversion?

Most roof light and dormer loft conversions fall under permitted development rules and therefore you won’t need to apply for planning permission. However, if you’re opting for a hip to gable or mansard loft conversion, you will need to apply for planning permission as these types of extensions are considered as major roof alteration works.

Remember, even if you don’t need planning permission for your loft conversion, you’ll still need to get it inspected by your local building control. Submitting your plans and having inspections costs between £400 and £800.

Cost example for a loft conversion

A loft conversion is no small project and there are lots of different parts required to make the room habitable. Take a look at the below table to give you an idea of the supply costs for a 30m2 conversion:

How long does a loft conversion take?

How long your loft conversion takes will depend on the type of extension you go for and how big it is. To give you a rough idea, we’ve put together the time it takes to complete each type of small, medium or large loft conversion.

Get competitive quotes

Make sure you get a range of quotes for your loft conversion so you can hear from a variety of builders to see what they would do with the space. Getting more than one quote protects you from being overcharged and also from being undercharged and being left with poor workmanship.

Post a job on HaMuch to get quotes from reputable builders in your area.

Estimates for common extension builder jobs;

	Job	Estimate
	Underpinning a house	£17,000
	Build a two storey extension	£90,000
	Build a timber frame extension	£29,000
	Install a swimming pool	£82,000
	Cost to build a single storey extension	£50,000
	Cost to build a side return extension	£61,000
	Install an RSJ	£1,075
	Build an outbuilding	£10,000
	Build a mansard loft conversion	£60,000
	Cost of a loft conversion	£43,000
	Build a kitchen extension	£50,000
	Build a hip to gable loft conversion	£47,500
	Build a granny annexe	£90,000
	Build a garden office	£10,000
	Convert a garage	£15,000
	Build a new garage	£18,500
	Build a flat roof extension	£21,700
	Build a dormer loft conversion	£42,000
	Lay a concrete foundation	£6,250
	Convert a bungalow loft	£30,000
	Basement conversion cost	£43,000

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