Timber frame extensions are becoming more and more popular in the UK. Lightweight and strong, you can build many types of extension with a timber frame with the knowledge that it’s a reliable and long-lasting material. But how much does it cost? We’ll go through the average cost of a timber frame extension and the costs per square metre in this guide.

How much does a timber frame extension cost?

How much a timber frame extension costs depends on a number of factors, but the average one storey timber frame extension of 4m x 5m is £29,000.

Item	Average cost
One storey 4m x 5m timber frame extension	£29,000
Two storey 8m x 10m timber frame extension	£43,000
Timber frame extension per m2	£1,450

The average cost of a timber frame extension per square metre ranges from £1,200 to £2,500, depending on how big your extension will be, and where you live.

Factors that can influence the cost of your timber frame include:

• Size: Larger extensions naturally require more materials and labour, so you’ll pay more. However, the cost per square metre usually goes down the larger your extension is.

• Design: If your timber frame involves an intricate design or you’ve added custom features, this can increase the cost.

• Materials: Opting for high-quality timber or specialised finishes can raise the cost, but you may find that the timber frame needs less maintenance or lasts longer, so you could save money in the long term.

• Where you live: Labour and material costs vary across the country, so your location has a big impact on the cost of your timber frame extension. Expect to pay more than our average prices above if you live in London or the south east, but less if you live in Scotland or other northern areas of the UK.

At HaMuch, we use our database of hourly and daily rates to help give you an estimate for your project based on your nearest town or city. Take a look at the table further down the page and find your location to get a more accurate estimate for your timber frame extension.

What is a timber frame extension?

A timber frame extension is a structural addition to a building constructed primarily from timber components. These extensions are built using a framework of wooden beams and panels, providing a sturdy and versatile structure that can integrate with existing buildings or add a distinctive modern look.

Timber frame extensions are much quicker and easier to build, are more sustainable, and offer lots of design possibilities. You can keep some of the beams exposed to create a classic look, or even incorporate some of the structural steelwork into the timber design to create something more contemporary.

Is a timber frame extension cheaper than traditional extensions?

Yes, in many cases timber frame extensions are cheaper than traditional extensions. Traditional extensions usually have masonry frames, i.e. bricks and mortar, and these materials cost more both physically and in transportation costs as they’re heavier.

Another reason why timber frame extensions can be cheaper is because the beams and other components can be fabricated off site then delivered ready to fit, reducing construction times.

Advantages and disadvantages of timber frame extensions

Advantages

Quick construction: Timber frame extensions can be erected quickly, reducing construction time and minimising disruption to your life.

Cost-effective: Timber is generally less expensive than traditional building materials like brick or stone, making timber frame extensions a cost-effective option.

Energy efficient: Timber frames have excellent thermal performance, so extensions built with these frames are usually quicker to heat up, retain more heat and are more comfortable while being environmentally friendly.

Versatile: There’s so much flexibility in design with timber frames. Customise and adapt your design with your architect to create a unique space that fits with your personality.

Sustainable: Timber is a renewable and sustainable building material, making timber frame extensions an environmentally-friendly choice compared to masonry frames.

Durable: When built to high standards and properly maintained, timber frame extensions can be durable and long-lasting, providing a reliable extension to your home.

Disadvantages

Less stability: Of course, timber isn’t as stable as materials like steel and concrete, so there is a risk of movement or shrinkage. However, if you hire a good extension builder who understands how to reduce the risk of movement and uses high quality engineered joists, this risk should be reduced.

Risk of rot: Timber is susceptible to moisture damage if not adequately protected, which can lead to decay or rot over time. Again, using an experienced builder who uses detailed timber should prevent these issues from arising.

Perceived fire risk: Although timber frame constructions will be fire-resistant when treated with fire-retardant materials, there is still a perceived fire risk compared to non-combustible materials like brick or concrete, which may make it more difficult to sell your home in the future if a potential buyer is put off by the timber construction.

Reduced acoustic performance: Timber frame structures may transmit more noise compared to traditional masonry constructions, as timber isn’t as dense. However, the correct insulation should help reduce any noise transmission. All new constructions must comply with building regulations around sound transference, so as long as you use a reputable builder your timber frame extension will meet these requirements anyway.

Trickier alterations: If you decide to make more improvements to your home in years to come, such as build another extension or switch your current timber frame extension to an open-plan space, it can be more difficult. You’ll need to consult a structural engineer so they can ensure that the structural integrity of your existing building is kept intact, especially if the work involves load bearing walls.

Perceived quality: If you intend to sell your property in the near future, potential buyers may perceive timber frame extensions as lower quality compared to traditional brick or stone constructions. However, this perception is changing as timber frame technologies and techniques advance, and their construction becomes more popular.

Do you need foundations for a timber frame extension?

Yes, as with any type of extension, timber frame extensions require foundations to support the weight of the structure.

The type of foundation needed will depend on various factors, including the size of the extension, the soil conditions and your local building regulations. Common foundation types for timber frame extensions include strip foundations, raft foundations or piled foundations.

Do timber frame extensions need planning permission?

In many cases, timber frame extensions won’t need planning permission due to permitted development rights. This is where you can build an extension to your home without planning permission if you meet certain requirements based on the extension’s dimensions, proposed use and location.

However, if you live in a conservation area or a listed building, there’s more chance that you will have to apply for planning permission. It’s always best to consult with your local building control before you start work to ensure you comply with all rules.

Are timber frame extensions warm?

Yes, timber frame extensions are very warm! Timber frame construction offers excellent thermal performance, making them inherently warm and energy-efficient. The insulating properties of wood help to regulate internal temperatures, so your space should remain warmer for longer. That means you’ll spend less on your heating bills in the colder months.

Can I build my own timber frame extension?

While it's technically possible for DIY enthusiasts to build their own timber frame extension, we wouldn’t recommend it. Although quicker and easier to build than masonry frame extensions, there are still lots of technical requirements to get right to ensure the frame is structurally sound and is load bearing.

Hire a professional builder with experience in timber frame construction to get the best result. They will understand building regulations, structural and safety requirements to make sure you’re not hit with any nasty surprises further down the line.

Will timber frame houses last?

When constructed to high standards and properly maintained, timber frame houses can last for generations. Modern timber treatments and construction techniques help to protect against rot, insect damage and other forms of deterioration.

Regular inspection and maintenance, including repainting or resealing exposed timber surfaces, can help to prolong the lifespan of a timber frame house. When you consider that old homes from the 1600s and before were built with timber frames and many are still standing, there’s no reason why yours can’t last for a century or more!

Ready to get a quote for a timber frame extension? Post your job on HaMuch now and we’ll send it to builders in your area who will be happy to cost up your project.

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