Flat Pack Extension Cost

Looking to buy a flat pack extension?

This guide covers everything you need to know about flat pack extensions, from how much they cost to things you need to consider that impact their price.

Depending on the type of extension assembly required, you can expect to pay in the region of £25,000 for a flat pack extension.

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How Much Are Flat Pack Extensions?

Flat pack extensions can range in cost from £25,000 to £35,000, depending on the exact dimensions, materials, and the complexity of the structure. This price is considering a single-storey 25 square metre flat pack extension, for supply costs only.

Your costs will rise in line with the size of your flat pack extension, as well as any additional jobs you're having added on as a result of the build.

This could include additional plumbing costs, ranging from £250 to £375 per day, home survey costs which start at £400, and your builder labour costs, which can range from £150 to £250 per day.

Flat Pack Extension Prices

Let's take a closer look at a complete quote for flat pack extensions in the UK:

This quote gives a complete overview of the costs you can expect when starting work on a flat pack extension. In addition to the actual 'kit' price for the extension itself, you will need to consider additional costs, such as homebuyer surveys, plumbing, and electrician fees.

For example, the cost of light fixtures and fittings can be in excess of £400 if an electrician needs to add new sockets, light fittings, and switches.

Flat Pack Extension Material Costs

Flat pack extensions can be supplied and assembled using different materials. The material you choose can impact the price, assembly time, and the build process.

Timber frame, oak frame, and steel frame are the three most common choices. Let's take a look at the costs and benefits of each material.

Timber frame extensions seem to be the most popular choice due to their affordability and ease of installation. A timber frame flat pack exttension can be installed within a week whereas steel and oak options can take a little longer, up to 2 weeks.

Additional Flat Pack Extension Costs

There are a few things to consider before planning a flat pack extension. Your property may require some structural changes, such as removing current supporting walls or fixing an uneven wall. The cost of removing a load bearing wall is around £1,500.

You might need a chartered surveyor to inform you of the condition of your property before the extension, so remember to factor this cost in as well. Home surveys, as noted in the table above, cost around £400.

You’ll have to hire someone to unearth the foundations and install the plumbing, electric, and gas before the extension can be put in place, like a standard house extension. You’ll need to factor this into the time scale, with the complexity of your structural changes adding a few days onto the job as well as extra costs.

You’ll also have to work with the expert to make sure your extension matches the décor of the rest of your house as closely as possible, as this could make the value of your home decrease when it comes to selling your home.

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What Impacts the Cost of Flat Pack Extensions?

The price you'll pay for your flat pack extension will depend on your choices:

• Size and dimensions: As with all home renovation projects, the larger your build, the higher your price will be.
• Quality of build: The higher the quality of materials, the higher your costs will be. Opting for eco-friendly materials and energy-efficient insulation will bump your price up when compared to entry-level materials.
• Choice of flat pack extension manufacturer: There are high- and low-end flat pack extension manufacturers - the more premium the company, the higher your costs.
• Additional work requirements: If your land needs significant work before the flat pack extension can be brought on-site, such as garden landscaping, garden levelling, or garden waste removal, the extra jobs will add more to your final project costs in labour fees.

With this being said, it can be cost-efficient to add extra garden labour work to your flat pack extension project to make the most of the labourers and gardeners already on-site to avoid further call-out fees.

Extension Groundwork Preparation Costs

Getting the ground prepared for your flat pack extension is critical for its stability and longevity. The type of preparation required will depend on how big your extension will be and the quality of soil it is being laid on.

Common Foundation Types

There are three common foundations used for flat pack extensions.

• Strip Foundations: Most common and cost-effective option. Continuous strips of concrete are laid to support the extension walls. Suitable for solid ground conditions.
• Raft Foundations: A complete concrete slab foundation that spreads the load over a larger area. Ideal for weaker or unstable soil.
• Pile Foundations: Used for very poor soil conditions. Where the load needs to be transferred deep underground via driven or bored piles. This is also the most expensive option.

The costs for groundwork preparation and foundations are not always included in your extension quote, so it is vital you understand what is required and the prices involved to avoid any unexpected costs.

On average strip foundations can cost between £1,000 to £3,000, Raft foundations typically range from £3,000 to £6,000. If you need pile foundations, they can exceed £6,000, depending on specific site conditions.

Flat Pack Extension Costs vs Other House Extensions

By now, we know that flat pack extension costs are lower than those of single storey extension - but by how much?

While a single-storey flat pack extension can cost in the region of £25,000 to £35,000, you can expect costs upwards of £30,000 for a basic quality single-storey house extension, while premium quality for the same size can set you back by £65,000.

Let's take a closer look:

Other Flat Pack Extensions vs Traditional Build Considerations

As well as price differences, there are also a variety of other factors to consider when deciding between a flat pack extension and a traditional build. Let's take a look in more detail.

Build Time

Flat pack extensions are designed for rapid assembly, so they are much faster to build. As many of their components are pre-manufactured, the need for on-site labour is streamlined. Onsite installation can be completed in as little as 2-4 weeks.

Traditional builds are much slower as all work will need to be done onsite. This will require many more man-hours, and with bad weather and supply delays pushing some projects up to 3-6 months before completion.

Quality of Construction

Flat pack extensions often provide a higher quality and consistent finish. As these are built in a factory with tighter quality control, the components that reach the site are manufactured to a high standard and guaranteed to fit seamlessly together.

Traditional builds can reach this high spec, but there are many more variables that can change on site, making the finish less predictable.

On-site Disruption

Disruption is more contained when dealing with a flat pack extension due to most of the build taking place off-site. This means less mess, less noise and fewer days onsite.

As well as taking more days, traditional builds will need scaffolding erected, numerous deliveries, potential weather delays and generally more disturbance.

Energy Efficiency

Flat pack extensions are often designed with energy efficiency in mind. As factory conditions allow for better precision and testing, they can incorporate high-quality insulation and energy-efficient materials that can help lower energy bills in the long run.

Traditional builds that are constructed to a high spec can also meet high efficiency standards. This can, however, differ between builds and does not offer the consistency that flat pack options do.

What Are the Benefits of Flat Pack Extensions?

Every homeowner will need extra space in their home at some point in their lives, with many people packing up and moving to a new house to gain that extra room. The additional costs you'll pay by moving house for extra space are practically endless, from stamp duty to estate agent fees, making it an expensive process.

Flat pack extensions are a great way of adding extra space to your home for a fraction of the cost of moving house, as well as being cheaper than the price of a traditional extension. But, not only are you going to have a whole extra room in your house, flat pack extensions will add significant value to your home when you decide to eventually sell it.

Most of the building work for the extension will be done away from your home, avoiding noise, mess and disruption to your everyday life. You could have your new flat pack extension installed within a week, depending on the complexity of the situation.

Let's take a look at the pros and cons of flat pack extensions to help you decide:

Pros of Flat Pack Extensions

• ✔ Cheaper than traditional home extensions, up to 25% in some cases.
• ✔ Most building is done off-site, meaning less noise and disruption while the work takes place.
• ✔ Adds value to your home, while giving you extra space for living.

Cons of Flat Pack Extensions

• ✖ Fewer choices for more bespoke designs.
• ✖ Less availability for flat pack extensions in the UK, leading to reduced choice of manufacturer.
• ✖ Lead times may be long to get the prefab extension brought to you.

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Can I Build a Flat Pack Extension Myself?

Whilst you could build your own flat pack extension yourself, it would take a lot of time, money and effort. It’s advised to leave a job this big to the professionals, as they are experienced and skilled in sourcing the correct materials for the extension.

It would be difficult to know where to begin doing this job yourself, and by the time you’ve got the materials, equipment and building plans together, you’d be spending the same amount of money but an awful lot more time to get the extension built and installed.

You will have to purchase a flat-pack extension kit for your prefabricated extension. A timber frame extension is one of the most popular flat pack extensions, and it's also environmentally friendly.

You would have to unearth the foundations and install plumbing, electricity and gas for the extension. We recommend comparing up to 3 quotes from professionals to make sure you get the best deal for your flat pack extension.

The Difference Between Flat Pack & Modular Extensions

Flat pack extensions and modular extensions both belong in the prefabrication construction category. However, there are significant differences in the design, assembly and use.

Flat pack extensions are delivered as pre-cut, pre-drilled components. Similar to DIY kits we are often used to with furniture, but designed for professional assembly. These components are then assembled onsite to create the finished extension.

Modular extensions are pre-constructed sections built in a factory environment. Each section or module is often a fully finished room or part of a building. This could include walls, floors, and sometimes even fixtures. Once transported to your site, the modules are assembled like building blocks to form the extension.

Checklist: Hiring a Flat Pack Extension Builder in the UK

When you're ready for that extra space, don’t forget to compare up to 3 quotes from professional tradespeople. Here's what we suggest when looking to hire a builder to construct your flat pack extension:

• Remember to shop around for your quotes - even if your first price is low. Comparing at least 3 quotes will give you a good idea of the price range for builders near you.
• Make sure you take a look at the builder's portfolio of previous prefab extension builds to see the kind of quality you can expect. Look for photos, videos, and be sure to read any customer reviews to get a feel for their work ethic.
• Ensure you get a written agreement. No matter how quickly you may want the job done, a written agreement will ensure you're covered against verbal agreements as the terms are laid down in writing for both parties, helping to mitigate any potential problems during the work.
• Be sure to check if your chosen builder is insured and holds the relevant liability for the work they're planning to undertake.