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What Is The Cheapest Way To Extend Your House On a Budget?

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What’s the cheapest way to extend if you are on a budget?

Extending your home is a popular way to increase space and add value to your property. With the hassle and costs of moving house – from legal fees to stamp duty – the reasons to stay put and improve your existing home soon mount up.

But where do you start with your extension plans?  

Whether you’re thinking of a garage conversion, side extension, or double or single-storey rear extension, there is much to consider for a home extension project. To help get you started, we cover planning rules, building regulations, dealing with the neighbours, and finding a builder.

Table of Contents

Extending a House on a Budget?

You must ensure that you have set aside a budget with 20% contingency for any unexpected surprises.  With higher materials and labour costs, it makes sense to agree a fixed price with your prospective builder.

How Much Value Does House Extension Add?

Like any big home improvement project, it’s worth sense-checking your home extension plans before diving in. Unless money is no object, it’s worth speaking to a good local estate agent who can give a view on whether your plan would add value to your home.

They should also be able to indicate how much it would increase the value, which will help inform your budgeting for the project.

Research conducted by the Nationwide Building Society suggests that extending a standard three-bedroom home with an additional bedroom and bathroom can potentially increase the property’s value by an impressive 23%.

However, The Times offers a more conservative estimate, suggesting a 5-10% boost when extending your property. It’s important to note that the specific type of extension you choose will also have an impact on the added value.

The cost of an extension can vary significantly depending on the extension type and the complexity. Factors such as building on uneven ground or needing specific building materials that match the style of your existing home and surrounding properties can drive up costs even before the construction begins.

If you want to create a larger kitchen or living area, a single-storey extension is a suitable option that can add around 10% to your property’s value. On average, a single-storey extension costs approximately £1,350-£1,750 per square metre, not including VAT for labour and materials. On the other hand, a loft conversion has the potential to add the most value to your property, ranging from 15-30%.

It is important to consider that this option can also be one of the most expensive, with costs ranging from £15,000-£60,000, depending on the type and condition of your roof.

Whilst a garage conversion can add less value than a loft conversion, and you will lose that dedicated space for car parking, this type of extension is usually more straightforward and costs less to create. The cost per square meter for a garage conversion is around £600-£1,000, depending on whether the garage is integral or attached (and more for a detached garage). This type of extension typically adds around 15% value to your property.

A double-height extension will cost more overall than a single-storey extension, but the cost per square meter works out a little less, averaging around £1,250-£1,650. This is because you will pay a comparable price for the building’s foundations and the roof. If you know you will need more space in the future and can afford the upfront expense, doing the build all in one go will be cheaper overall. Additionally, a double-height extension has the potential to add more value, typically between 12-20%.

Who designs an extension?
You may extend your home without planning permission, referred to as your “permitted development rights”. 

What Is The Difference Between Permitted Development And Planning Permission?

In brief, full planning permission involves requesting permission to construct a project, while permitted development only requires giving notice of your intention to proceed. The concept of planning permission is quite subjective, as it can be interpreted differently by different boroughs and individual case officers.

You may extend your home without planning permission, referred to as your “permitted development rights”.  Always check with your local council’s planning department, as over-extending means you will be issued a planning enforcement notice, making it difficult to sell your house.

Under the rules, the rear wall of a detached home can be extended by 8m to the rear if it is a single-storey property and 3m if it is double-storey. This is reduced to 6m in a semi or terraced house.

There are also height restrictions. A single-storey extension cannot be higher than 4m to the ridge and the eaves. The ridge heights of any extension must not be higher than the existing property. Double-storey extensions mustn’t be closer than 7m to the rear boundary.

Other conditions must be met. For example, you will need planning permission if the extension is more than half the land area around the original house. Extensions must be built with similar materials to the existing property.

Different planning rules may also apply if your home is in a Conservation Area. For any renovations to a Listed Property, you will need to obtain listed building consent.

Did You Know?

When considering an extension, it is important not to spend significantly more on the project than the maximum value it could add to your property. For example, if your home is valued at £300,000 and the highest price for properties on your street is around £350,000, spending £100,000 on an extension would unlikely yield a return on your investment if and when you decide to sell.

What Do You Mean By Building Regulations?

Building Regulations establish standards for building design and construction. These standards aim to ensure the safety and health of people, including those with disabilities, within and around buildings. Additionally, they help in conserving fuel and power.

Whether or not planning permission is required, any renovation project must comply with building regulations. You’ll need to ensure whoever carries out the work can either self-certify the work (for example, FENSA accredited window fitters, Gas Safe registered gas engineers and NICEIC registered electricians and so on) or will liaise with the local Building Control Officers at your council to have their work certified.

If the requirements aren’t met, you could be served with a notice to take the extension down and will have trouble when it comes to selling your home without the relevant Building Regulations certificates.

Do I Need To Tell House Insurance About Extension?

Yes, you need to inform your insurance provider about your work. If your insurer is not aware of your building work and your plans to add an extension, it can void your policy.

The extension will likely increase the rebuild cost of your house.

Insurers take this into account when pricing premiums. While building work is being undertaken, it could put the property at risk of damage.

If you don’t let your insurer know and there’s a problem with the property at some point, you may find your policy is void. Your insurer will inform you if your current policy covers the new extension.

You may find your premiums increase. If, for some reason, they are unable to cover the property now, you’ll need to find a new provider before your cover is cancelled.

You should also check that any builder working on your property has professional indemnity insurance to cover the costs should something go wrong.

How much does an architect charge to design an extension?
In many cases, the freeholder's consent is necessary before undertaking major changes, such as building an extension.

Can I Put An Extension On a Leasehold Property?

Leasehold properties have their own rules, outlined in the lease agreement and referred to as covenants.

Among these, there are restrictive covenants that restrict certain actions. In many cases, the freeholder’s consent is necessary before undertaking major changes, such as building an extension.

Do Neighbours Have To Agree To An Extension?

Yes, it is important to maintain a good relationship with your neighbours. This is because they have the ability to obtain an injunction that would prevent you from building your extension.

Building projects can be a major cause of disputes between neighbours. If planning permission is required, your neighbours will be consulted by the local planning authority. Still, it’s a good idea to let them know about your plans well in advance, particularly if the works may cause disruption.

Do I Need a Party Wall Agreement For An Extension?

If you plan to extend your property and the extension involves work on a party wall, it is important to have a Party Wall Agreement in place. This agreement is necessary because you can only proceed with building the extension on the Party Wall if the homeowners of the adjoining property consent to the work.

In the event that they refuse or a dispute arises, it will be necessary to hire a surveyor to draw up the Party Wall Agreement. This ensures that the rights and responsibilities of all parties involved are clearly outlined and protected.

A party wall is a shared wall, usually between a terrace or semi-detached house, and divides the homes of two owners. It also includes garden walls built over a boundary and excavations close to a neighbour’s property (within three or six meters, depending on the depth of the new foundations).

Party Wall Agreements between neighbours are most needed for loft conversions and extensions, which require the insertion of steel supports, a damp proof course and/or the digging of new foundations.

How much does it cost to get plans drawn up for an extension?
Using an architect means they will be able to help you come up with cost-efficient designs.

Do I Need An Architect To Design My Extension?

It is easier to hire an architect to draw professional plans that look credible to the planning committee.  Using an architect means they will be able to help you come up with cost-efficient designs.

How To Find a Reliable Builder?

A reliable builder is the key to any successful home improvement project. Online review sites are a good place to start when comparing builders and other contractors.

We suggest the Federation of Master Builders (FMB) because they check company history, financial records, and proof of insurance. All their member’s work will also be checked on-site by an independent inspector to ensure it’s completed to a high standard.

How Much Should I Budget For a House Extension?

The cost of a home extension will depend on the size of the extension, the structural work involved (will you need steel) and where you are undertaking the project.

As a rough guide, the average 4m x 6m extension costs £26,000 to £34,000, according to My Builder.

Bear in mind the cost of a two-story extension is not that different to a single-story structure as most of the cost is in the foundations.

We recommend getting quotes from three different builders for the work.

Getting Quotes

Whenever you are undertaking a renovation project, it’s always a good idea to shop around. We recommend getting quotes from three different builders for the work. You’ll usually need to ask at least five firms to get three quotes.

Setting a Budget

When setting a budget for your job, start by making a list of everything you would like included. Compare your quotes item by item, and when pricing services and materials, always check the VAT is included.

We’d also recommend setting aside around 10% of the total cost for unexpected additional costs.

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