What is a timber frame house?
A timber frame house is a building system made of individual timber components which are then joined together. Usually, this is a network of panelised walls and floors, with timber studs carrying the vertical and horizontal loads and transferring them to the foundations.
A timber frame could be a smart choice for your self build as the method comes with many advantages, it’s particularly suitable if you are looking for an excellent thermal performance using sustainable materials. You will also benefit if you are looking for a quicker build, or if the ground conditions on your plot are a concern. There are lots of factors that you’ll want to consider and to help you get started, we’ve shared our best advice below.
11 Advantages of timber frame construction
Timber-frame construction is fast becoming the most popular option for self-builders, In fact, the advantages of timber-frame construction vastly outstrip the disadvantages, and many things including the speed of build, sustainability, energy efficiency, and more all contribute to how good timber-frame construction really is.
Here are 11 benefits of building with a timber frame:
- Fast build time
- Reduced onsite labour
- Low waste volume
- Reduced thermal bridging
- Excellent thermal performance
- Load bearing
- Slim profile
- Controlled budgeting
- Factory quality
Closed-panel timber-frame construction is an offsite method of construction, which means the panels are prefabricated in the factory before being erected onsite. This gives rise to a rapid construction time, which helps to keep the build on track.
At Potton the timber frame wall panel systems are supplied as part of a package, which also include other components such as internal walls and the structures of the floors and roof. This part of the build is overseen by a contracts manager, allowing you to focus on other parts of your self-build project.
Reduced time onsite not only reduces site labour, it also lowers the environmental impact and disruption to local residents. There is significantly less waste at a timber-frame construction site than at a masonry one, because the bulk of the manufacturing takes place in the factory. This means there is a low volume of waste onsite, which is not only better for the environment, it saves hiring multiple skips for waste removal.
Within our timber-frame kit we have an optional weathertight package. This delivers the superstructure to a secure, weathertight stage and allows internal works to start earlier. The weathertight package also ensures a single point of responsibility for the build, up to this stage.
Thermal bridging, also known as cold bridging, refers to the points of heat loss in a building envelope. These are usually around junctions where two components are joined together. Thermal bridges within a building affect its thermal efficiency, and a poorly insulated structures will naturally mean higher energy bills.
With masonry construction, there are joins between every single block, with opportunities for heat to escape. When using a timber-frame panel there is a much larger surface area with fewer junctions, and at Potton we also use a continuous insulative lining to reduce areas of thermal bridging.
Kingspan ULTIMA provides a level of performance that exceeds SAP guidelines. SAP calculations help to define the Energy Performance Certificate (EPC) of a house, which is used to help determine the value of a home, therefore, achieving good thermal values can be hugely beneficial. With Kingspan ULTIMA, your EPC will measure on the high end of the scale, contributing alongside other energy efficient products.
Houses built with timber frames achieve lower U-values compared to masonry builds of an equivalent wall thickness, this significantly lowers heating costs and the home’s carbon footprint.
Closed panel timber frames are built with insulation, known as a fabric-first approach. They offer reduced rates of thermal bridging and achieve excellent airtightness levels, that contribute to low fuel costs and help achieve a comfortable internal environment to live in.
Closed-panel timber frames are lightweight, composite panels, that allow for higher ceilings and larger spans. This gives you greater flexibility, particularly for open-plan areas, allowing for greater freedom in your design. As the frames are engineered and manufactured to fit specified dimensions, architectural drawings can be produced with precision.
Timber-frame construction has a slim wall build up as closed-panel timber frames have insulation built into the panel. When building with brick and block you require many more layers of insulation to surround it, therefore masonry walls would need to thicker to achieve the equivalent level of thermal performance.
Using timber frame can free up more room for you to enjoy. Taking off inches from every wall may not seem significant, but can increase the overall internal floor plan. One of the key methods when valuing a property is assessing the amount of internal floor area. Usually the more floor space you have, the greater the value of your home.
With outdoor construction methods such as brick and block, the bulk of the work needs to occur onsite. This can lead to issues when the weather is wet, or when relying on multiple deliveries from different suppliers. These potential delays can have a knock-on effect, not only to the build schedule, but also to your budget.
As timber frames are partly manufactured offsite, you will have a more accurate costing, as there are fewer variables. This allows you to develop an efficient build schedule that you are unlikely to deviate from.
Timber-frame construction is a ‘dry’ form of construction, and even if it is wet onsite work can continue regardless. Which means your economic risk factor is lower when working with timber frames compared to other build methods.
At Potton. all our timber products are legally sourced from well managed forests in accordance with the UK timber regulations. Timber is also one of the few sustainable resources used in mainstream construction, compared to the manufacture of bricks and concrete that rely upon raw, finite materials. Timber has a significantly lower carbon footprint than steel for example, because it requires far less energy for cultivation, extraction, and manufacture. In fact, well managed forests act as carbon stores and create valuable ecosystems for local flora and fauna.
At Potton each structural frame is computer controlled and engineered to fit each design. The frame is then manufactured in our factory according to these dimensions, meaning accuracy and high quality is standard for timber-frame construction.
Offsite manufacture, onsite build!
At Potton, our structural timber solutions are available for almost every type of building and our established factory-based manufacturing process provides a high level of dimensional accuracy. Meaning you receive good quality components, to help your project run smoothly.
Offsite construction methods also help reduce the risk of accidents. As a lot of the work happens within a controlled factory environment. Particularly important on self-build sites, that tend to run without full-time site managers.
Top timber frame myths explained
Building with timber is a great solution for self-builders, but there are many myths that need explaining. We’ve put together this quick guide, to help you understand more about building with timber.
- Are timber frame homes stable?
In short, yes. The flexibility of timber-frame construction, means they are suited to gusty exposed locations, whereas other construction methods might result in cracking. For this reason, timber-framed houses are often used in countries with seismic activity. So even if your plot is ravaged by coastal winds or Highland gales, a timber frame will be more than suitable.
- Is there a fire risk?
As timber frame houses are made from wood, it is natural to worry they would be more prone to fire. All buildings constructed in the UK have to adhere to building regulations. At Potton all our build systems adhere to current building regulations, with additional independent fire test certification.
- Will my timber frame house rot?
Wood is a natural material so there can be concerns that timber-framed houses are subject to rot and infestation. However, structural timbers are kiln-dried to reduce moisture content. Stress-graded to meet engineering standards, and pressure treated with a preservative. This protects against rot and fungal attack and ensures structural stability and durability. The timber-frame panels used in the walls of your Potton home, will have several measures in place, including membranes and vapour-control layers to ensure the inside of your panel stays moisture free.
- Are timber frame homes cold?
Timber is a natural insulator, and can store heat more effectively than many of its counterparts, it can offer greater thermal effectiveness to the equivalent thickness of brick. All Potton homes are inbuilt with market-leading insulation, so your new home should feel warmer than what you're used to and be more energy efficient!
- Will a timber frame home be noisy?
A timber frame home will not be any noisier than a home built from bricks and mortar as the materials and insulation used within the walls can help its acoustic performance.
- Can I Get Insurance and a Mortgage for a Timber Frame House?
Building a timber-frame home - step by step
- Building the footings and floor structure
In most cases, your groundworker will use a traditional strip foundation approach, digging trenches to the depth and width required by the foundation design, then filling them with poured, ready-mixed concrete. An initial two to three courses of blockwork are then laid, with openings for service entries or exits created by pre-cast concrete lintels. Next the ground floor structure is installed, which is typically a beam and block floor with pre-cast concrete beams to span between load-bearing walls. The gaps in between the beams are then filled in with concrete blocks laid flat and in some systems the concrete beams are replaced with insulating polystyrene elements. In both cases, a damp-proof membrane will need to be incorporated into the floor. Insulation is then added, and then a thin ‘slip’ membrane is used to separate it from the screed. The insulation and screed stages often happen after the building structure is erected, and for most of our customer’s the screed incorporates the underfloor heating pipes.
- Building the walls
The substructure and ground floor works are completed with a ‘kicker-brick’ course of blocks, on top of the beam and block floor. These form a square and level surface on which the first part of the timber frame, the sole plates, are fixed. It’s critical that the sole plate is level and square as it sets out the rest of the building. The ground-floor external wall panels are then delivered as prefabricated elements complete with insulation and membranes from the factory. To erect the structure a crane is usually used to lift, position and manoeuvre each panel into place.
- The floors
The floor joists are fitted to the top of the wall panels, for the first-floor deck we use chipboard with a permanent weather-proof coating. This is then glued and nailed into position on top of the joists, the process is repeated for additional storeys and then the roof structure sits on top of the wall plates on the external walls. At Potton we always use metal open-web joists for the structure of the floor these simplify the positioning of services compared to solid timber or I-joists. They also enable wider spans to be constructed before additional beams.
- The roof structure
We use a variety of roof structures, which one we choose for your project depends on your specifications and design. In particular whether the roof space is being used as living space or not. Roof structures are either trussed rafters, attic trusses, loose cut roof or panelised roof systems. For example Kingspan TEK® structural insulated panels.
- Making the build weathertight
The whole timber frame is wrapped in a breather membrane, to stop water entering and to allow moisture to escape. Depending on how rigorous the airtightness needs to be, joints between panels and window openings might be sealed with specialist tapes and seals. Once the structure is up, the roof should be ‘felt, battened and tiled’ as quickly as possible. Next come the windows and doors, after which the structure is effectively weathertight. Once the building is weathertight work can carry on inside and outside the building. This is a major advantage as tradespeople can start to complete their parts of the build.
- First-fix carpentry works
With the house weathertight, internal works can begin, starting with first-fix carpentry work which is preparation for plaster boarding, electrical, plumbing, heating and ventilation works. Once the first-fix carpentry work is completed, other trades can follow on, so the property is ready for plasterboard dry-lining. We recommend the use of tapered edge taped and jointed plasterboard, but many customers prefer to skim. In practice, the difference is minimal as long as the team applying the skim coat are tidy in their work.
The glamourous bit, not to be rushed! The construction process ends with second-fix electrics, plumbing and carpentry. This is where all the surface elements of the house are installed, from kitchen units, light and power sockets to bathroom taps and staircases. The house is then ready for tiling, painting and decorating and the fitting of flooring.
Understanding the build process will help you decide which materials are best for your self build. At Potton we specialise in timber frame and SIPs build systems, that have many advantages and benefits for the self-builder.
Timber Frame vs SIPs
Many people are beginning to move away from masonry as the default self build option, with alternative building methods experiencing a boom in popularity. Many have a shorter build time, prioritise sustainability and are more energy efficient. Two methods that have these benefits are timber-frames and SIPs (structurally insulated panels). Both are timber-based systems, easy to erect and offer similar thermal performance levels.
When deciding upon a build system, keep in mind these five important elements:
- Wall thickness
- Construction speed
- Trusted service, when comparing suppliers
Comparison on U-values
U-values are a way of measuring heat loss, in this case through a wall system. The lower the u-value, the better the heat retention and the greater the energy efficiency.
Building regulations requirements for u-values have become very complicated in recent years and will vary depending on other factors in the construction. Generally, walls need to have a low u-value for energy efficiency.
All materials and systems on offer claim to provide u-values of around 0.15. There is some variation, some get down to 0.11, others up to 0.2.
Potton’s timber frame build systems
Potton offers two main build systems, Kingspan ULTIMA and Kingspan TEK®. Each with their own benefits, and each with differing U-values. As illustrated in this thermal characteristics comparison table below.
|Kingspan ULTIMA||Kingspan TEK®|
|Build System||Timber Frame||SIPs|
|U-value (with brick cladding)||0.15 - 0.13||0.18 - 0.09|
When comparing build systems, it is important to look at the total thickness of the wall. This is critical given the need for a higher amount of insulation in the structure. Potton’s Structural Insulated Panel system, Kingspan TEK®, utilises either a 142mm or 172mm thick panel. This is in addition to the external choice of cladding, giving a wall thickness from 345mm. This will make a big difference if you’re building on a small site, such as an urban location or where the planning department insists on a small footprint. This could have an impact on the useable floor area of the rooms. Kingspan ULTIMA wall systems also offers similar levels of wall thickness.
All modern timber frame systems involve a degree of off-siting, taking work away from the site and into a factory setting. This is generally considered a good thing as factory is controllable, programmable, accurate and dry. All factors which can speed up the process!
What are the types of build systems?
- Closed panel timber frame. For example Potton's Kingspan ULTIMA
- Structural Insulated Panels known as SIPs. For example Potton's Kingspan TEK®
Extreme ‘modular’ style closed panel systems could come with window units, electrics, heating, and plumbing systems pre-fitted then delivered to site. There is no question that the move towards panelisation speeds up the amount of time on site. So it not only reduces live ‘build’ time but also ensures your project doesn’t fall victim to the usual delays such as weather, limited working hours during winter, tradesmen on site, and so on. This is one of the main reason that timber systems are popular in Northern climates. However, it’s worth bearing in mind that closed panel and SIPs systems can take 3-4 weeks to manufacture.
Building system costs
For most people, cost is a significant factor when deciding which building system to use., which is understandable, but there are some other vital factors to bear in mind.
Are you comparing similar building systems?
There could be differences in specification, for example the type of insulation, membrane and quality of timber. Are all the wall system components included in the price?
What are the labour costs?
Many companies recommend approved fitters, which could mean that different installers will charge different labour costs.
And lastly, but most importantly, remember the big picture
Wall systems can account for 15-25% of the overall cost of construction. It’s an important part of your build and worth investing in a quality item that will perform and last. You can easily replace a bathroom but replacing your walls is a different story!
Trusted service, when comparing timber frame suppliers
Buying a timber frame is one of the most significant purchases you will make for your self build project. Which is why it’s important to look for a supplier with a good level of customer service. They should be able to provide:
- A team of professionals, with complete support and advice
- Experienced and proven success within the self build process
- A tailored experience to your bespoke project
- Established company, giving you peace of mind and reassurance that your investment is in good hands.
Will your timber frame supplier be able to:
- Store a timber frame system for an extra week if there is a delay to your groundwork?
- Be here to help through the process, to reassure you that everything is running smoothly?
- Give you confidence as an established company in delivering build systems with success?
- Provide good references through previous clients?
Make sure you consider ALL of the above, as choosing the right supplier will be key to how your self build will progress.