Timber frame extensions are currently very popular among planners, builders and homeowners in the UK. But why do people want these wooden extensions?
Compared to brick-built extensions, building a timber frame extension is overall cheaper and faster to erect. Moreover, we’ll look at these and other reasons in more detail later.
Typically, timber framing costs per m2 range from £1500 to £2500, including planning, material purchase, and building. If you want expensive hardwoods, timber frame extension costs sit at the upper section of the range because of the high cost of timber like this. In comparison, cheap softwood sits at the other end of the range.
It’s faster to erect timber-framed extensions too. On average, a small extension having an area of around 15m2 takes about 4 to 6 weeks. Furthermore, a large extension of around 60m2 takes between 10 and 12 weeks to erect.
Let’s consider what makes a timber frame building better than traditional building methods.
They are lightweight, cost-effective, and very adaptable; you can add timber framing to almost any type of building without it looking out of place. But, undoubtedly, the most attractive feature is the speed of assembly. Panels and roof timbers are factory-made, delivered to the construction site and speedily assembled into your new extension in much less time than traditional brick and mortar construction.
Many factors influence the price. And, we’ll explore these later in this guide.
How Much Does a Timber Framed Extension Cost?*
The table below shows typical timber-framed extension prices per square metre in the UK. You can use this as a cost calculator to work out what is the best for you.
|Extension Size||Type of Timber||Cost per m2||Total Cost|
|15m2 Single Storey||Softwood||£1,500-£1,900||£22,500-£28,500|
|30m2 Single Storey||£45,000-£57,000|
|30m2 Double Storey |
(2 x 15m2 Storeys)
|15m2 Single Storey||Maple||£1,600-£2,100||£24,000-£31,500|
|30m2 Single Storey||£48,000-£63,000|
|30m2 Double Storey |
(2 x 15m2 Storeys)
|15m2 Single Storey||White Oak||£1,900-£2,300||£28,500-£34,500|
|30m2 Single Storey||£57,000-£69,000|
|30m2 Double Storey |
(2 x 15m2 Storeys)
|15m2 Single Storey||Red Oak||£2,000-£2,500||£30,000-£37,500|
|30m2 Single Storey||£60,000-£75,000|
|30m2 Double Storey |
(2 x 15m2 Storeys)
*Note: prices are estimates, and you should use them as a starting point for your own research. We calculated the average prices based on costs per square metre, researched at the time of writing (July 2021).
Timber Frame Extension Price Factors
Several factors affect the overall price of a timber-framed extension. Here are a few of the most important.
Size of Extension
When talking about size, we mean floor area and the number of storeys. The total price per metre for a single storey made from standard softwood is between £1,500 to £1,900, including materials, planning, manufacture and installation.
If you decide to have another storey above the ground floor, use a rule of thumb to increase these prices by one half. That is, multiply the single storey costs by 1.5. You can get away with this because you’ve already paid for the roof when estimating the single storey prices.
If you decide on more levels than this, you must start thinking about using heavier structural timber on the ground floor to carry the increased weight above.
Although the most cost-effective (and commonest) wood used for a timber house extension is softwood, sometimes the designer needs the properties of other species of timber to fulfil a design requirement. The other common types of structural wood are
- Maple – at around £1,600 to £2,100/m2, all-inclusive.
- White Oak – at about £1,900 to £2,300/m2, all-inclusive.
- Red Oak – with an all-in cost of £2,000 to £2,500/m2.
Labour prices vary around the country depending on the standard of living. Northern Ireland and the North of England usually have the lowest prices, while the Midlands and South Wales are slightly more. Moreover, the next highest labour rates are in East Anglia, Scotland, and the Southwest of England. Then, Southeast England, including Hampshire, South Midlands, Kent and Outer London. Finally, you’ll find the most expensive labour rates if you live in Inner London. Overall, London is about 20% more than rates in the least costly region.
In contrast, the price of materials used to make timber frame will be approximately the same all over the country.
Type of Extension
The type of extension you choose affects the overall price.
For example, you’ll need additional timber placed at specific locations to support wall cupboards if you want a kitchen extension. Similarly, you must take into account the extra wiring required for various electrical appliances. You also have to consider where the plumbing and drainage come from and go to.
You must also consider the different types of timber-frame methods.
Platform Frame Method
This method involves making each wall panel into load-bearing support for the floor above. It’s possible to construct buildings of up to seven storeys using this method. Particular advantages are that the designer specifies shorter lengths of timber for each panel, and the contractors have a working platform at each level.
Vertical Pane Frame
This method uses vertical timber lengths to create structural supports. This is probably the most common method as it uses timber as a structure for the panels and the substructure. It also means that you need less skilled labour on the job, and you enjoy a significantly faster construction speed.
The modular units used in this timber-frame method can be combined to produce the entire building without additional support or substructure. This type is usually manufactured in a factory under strict quality control and transferred to the site as a timber frame extension kit, assembled on-site by specialist labour.
The standard estimated price you get from a timber frame company covers the outer walls’ inner leaf, flooring, ceiling and roof timbers.
Many people forget about the outer wall covering, wall and loft insulation, foundations and concrete ground floor, roof covering, internal joinery etc.
All these extras will considerably increase the overall price of the timber-framed structure, especially the outer skin, depending on what material you intend to use. Some people choose an outer skin of timber with a breather membrane followed by a cement render. Alternatively, they might use concrete block and cement render. In contrast, others prefer a brick skin to match the material of the existing house.
Estimated Timelines & Labour Cost Examples
Building a timber-framed extension takes qualified tradesmen around 6 to 8 weeks for a small one (15m2), 10 to 12 weeks for a medium extension (30m2), and 12 to 14 weeks for a large extension (60m2). These durations are approximate as many things can affect how the job runs. Many unforeseen circumstances can set you behind by many days, especially if a spell of bad weather arrives unexpectedly.
You need a variety of tradespeople to carry out the different tasks necessary for your extension. However, even if you think you can do part of this as a DIY project, you can only consider the painting, as the other trades involve structural construction, waterproofing the house, and utilities. None of which should be done by an amateur.
|Tradesmen Type||Typical Average Daily Rate (incl VAT)|
|Architect||Around 10% of total job cost|
Building a Timber Framed Extension Overview
Detailed instructions for building a timber-frame extension are not relevant here as every design is individual to the type of extension, its size, and the appearance of your existing house. Instead, we’ll give you general indications as to the order of the steps needed for the build. Assume the project is a wooden extension on a brick house.
- Visit the architect and explain what you want to build. The architect will know whether you need planning permission, draw the appropriate plans and organise the application. You must not start buying any materials or hiring contractors until the council has passed the application. There can be one of three decisions. 1) pass the application as it stands; 2) pass the application with amendments; 3) fail the application. Let’s assume the application has passed as it stands.
- The architect draws plans suitable for the contractor, taking into account the building regulations.
- Distribute the plans to various contractors and ask for a quotation. You then choose contractors for the timber-frame construction, usually a specialist company. The other is a building company with employees able to assemble the timber frame on-site and do the extra work.
- After choosing the contractors, start on the foundations. These involve concrete footings and concrete blocks to the DPC level. Then pour a concrete floor.
- Meanwhile, the timber-frame contractor builds the panels in the factory ready for delivery.
- After delivery, assemble the frame panels onto the concrete block footings.
- Once you’ve completed the wall panels, lift the roof trusses into place and install them as per the drawings.
- Next, a bricklayer builds the outer skin using bricks to match the house. At this stage, the contractor installs the windows and external door frames and doors.
- Roofers cover the roof trusses with membrane and tiles.
- Finally, the extension is now watertight, and work can continue inside.
Timber Frame Extension vs Brick
There are significant differences between brick and timber frame. The main difference is the timeframe for the completion of the project. Without a doubt, it’s much faster to install a timber frame building. Moreover, timber frame panels are lighter than the corresponding area of brickwork and easier to install. Furthermore, while the cost of brick and timber-frame panels are approximately the same price, you will find that the job takes less time to finish using panels. Therefore, significantly reducing the labour cost.
Usually, structural-grade construction timber has a guaranteed lifespan of around 40 to 50 years. In comparison, masonry products can last up to 150 years. And clay bricks have lifespans of many hundreds of years. Therefore, discuss all the pros and cons with your architect and contractor before committing to the construction method.
UK Planning Permission & Building Regulations
Your extension might need planning permission depending on:
- the area in which you live.
- The extension’s floor area and volume.
- Does its design compare well with your existing property and those of your neighbours?
- How far it is from your boundary.
However, you should consult the local authority or your architect at the planning stage for more information. But, you must understand that the local council will enforce the rules, whether timber-frame or masonry.
There are also fees associated with planning permission. A planning application costs around £460 for a complete home, while an extension costs around £200. Check with your local planning office for exact amounts.
However, you must comply with the appropriate building regulations.
The building regulations cover various topics related to structural and fire safety, energy efficiency, ventilation, drainage, damp, electricity, plumbing, and quality of materials and craftsmanship.
Protection From Fire
Because of the large amount of wood used in timber-framed buildings, fire safety is probably more critical than in a masonry building.
The fire protection regulations aim to reduce the risk of a fire starting on your property. And, if a fire manages to ignite, they ensure that you have an adequate fire evacuation procedure in place.
Therefore, you can’t use ordinary construction timber in the timber frame. You can only use fire-resistant and treated construction timber. Furthermore, all walls and floors must have fire-resistant linings.
Your architect will know what rules are in place and will design the extension accordingly. Likewise, the building control office will be looking for these critical materials and specifications in the plans.
Timber Framed Extension FAQ
Is it cheaper to build a timber frame extension?
Generally, a timber frame building will be cheaper than a masonry building. The reason is mainly that the framed building takes less time to build.
Do you need footings for a timber frame extension?
Yes. A timber frame building, just like any other, must stand on firm foundations to prevent movement and subsidence. Therefore, the extension needs concrete footings, followed by concrete block masonry up to the damp proof course (DPC) level. Above DPC, you can start on the timber frame.
What are the disadvantages of timber frame construction?
The main disadvantage is that timber frame panels rot, just like any timber. Yes, the wood will be treated with preservative, but this has a finite lifespan.
Can I build a wooden extension without planning permission?
The answer to this question depends on what you intend to build. You have permitted development rights, which specifies what you can and cannot do. Fortunately, the government has listed the rules you must follow to build without planning permission. You can find out more about this on the Planning Portal website.
What size extension can I build without planning permission?
You can find the regulations specifying the size of your extension on the Planning Portal.
Generally, the extensions sit in the following categories: single-storey extensions, extensions with more than one storey, and side extensions.
Generally, the main rules covering all extensions are as follows.
- You can build on no more than half the land around the “original house”.
- Extensions cannot have roofs or eaves higher than those on the existing house.
- If the extension is closer than two metres from the boundary, the height at the eaves must not be higher than three metres.
- You must not build an extension forward of the ‘principal elevation’.
Look on the indicated website or contact your local council for advice about permitted development rights.
If you want more space in your home and don’t want to move house, consider building a timber-framed extension. They’re cheaper and quicker to build than a traditionally made masonry extension. Therefore, before you know it, you’ll be enjoying the benefit of more living space. But you need professional help to plan and build the extension.
Complete the form on this page, and you’ll receive 2 to 3 quotes specifying timber frame extension costs that are competitive and probably well within your budget.