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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To find out everything you need to know ahead of your flat pack extension project, keep reading.

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 extension 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:

What Are the Benefits of Flat Pack Extensions?

Many homeowners will need extra space at some point in their lives, which often leads to moving house to gain that extra room. The additional costs you'll pay by relocating include everything from stamp duty to estate agent fees, making it an expensive process.

However, flat pack extensions are a great way of adding extra space to your home for a fraction of the cost compared to moving house, as well as being cheaper than the price of a traditional extension.

Below are some of the key benefits of flat pack extensions:

• Build Time: Flat pack extensions are designed to be installed within a short turnaround. By using pre-manufactured components, an on-site installation can be completed in as little as 2–4 weeks (compared to between 3 to 6 weeks for traditional builds).
• Quality of Construction: Flat pack extensions come with a high-standard of quality control due to being made in a controlled factory-based environment, meaning they are checked before leaving the premises to ensure a polished finish.
• Less Disruption: With the majority of construction happening off-site, flat pack extensions create less disruption than traditional builds. There's less time spent onsite, with fewer workman and equipment, as well as less deliveries.
• Energy Efficiency: Using precision-built components and high-quality insulation, flat pack extensions are designed to deliver consistent performance, whereas results on traditional builds can vary more from project to project.

Pros and Cons of Flat Pack Extensions

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

Pros

• ✔ 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.
• ✔ Greater consistency in energy performance and potential to lower your bills.

Cons

• ✖ 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:

• Do they have good experience? 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. Ask about their most recent jobs and how long they've been trading.
• Do they have positive reviews? As well as looking through their previous work, it's good to ask for recommendations and check for online reviews via sites such as their MyJobQuote profile for any customer feedback.
• Do they have valid insurance? Although not a legal requirement, reputable companies will at least hold public liability insurance for the work they're planning to undertake, covering against personal injury and accidental damage.
• Have you asked for multiple quotes? Remember to shop around by comparing at least 3 quotes for a good idea of the price range of builders in your area. By using MyJobQuote we can help you find local tradesmen without any commitment to go ahead with the work.
• Are they able to provide a quote in writing? Ensure you have a written agreement on what's included and the work that is expected to take place. This not only helps understand what you're paying for, but also eliminates any confusion.
• Is waste removal included? One of the key things to look out for within an itemised quote is the removal of any waste, the last thing you want to happen is be left with the cost and inconvenience of clearing up debris.
• Will they arrange building control sign-off? As a new extension needs to follow building regulations and may need to planning permission before going ahead with the work, it's important to have someone knowledgable in signing-off the job.