Technical Specifications

What Do You Need to Know About Oak?

Why Homeowners Choose Green Oak

When you choose one of our oak-framed buildings, you’re choosing green oak. This is freshly cut timber that still contains natural moisture. It’s the same method that has been used in English carpentry for centuries and is renowned for creating frames that grow stronger and more characterful over time.

Green oak remains the material of choice for discerning homeowners because:

It’s Naturally Strong and Long-Lasting: Oak has an unmatched ability to stand the test of time. Many oak-framed buildings have lasted for hundreds of years, demonstrating the material’s enduring strength and resilience.

It Has a Precision Fit That Improves with Age: As green oak naturally dries, its joints tighten, locking the frame together for exceptional stability and strength. The result is a building that gets stronger over time.

It’s Completely Sustainable: Oak is a renewable, ethically sourced material that requires minimal processing. English Heritage Buildings’ wood is sourced from one responsibly managed forest that cultivates trees specifically for this purpose, and plants extra in their place.

It’s Warm, Inviting, and Full of Character: The subtle variations in oak’s grain, tone, and texture create a rich, authentic aesthetic that brings a sense of warmth and natural beauty to any home.

The Benefits of Oak for Your Home

Once you’ve decided on and installed a green oak-framed building, structure or extension, you’ll notice some other benefits for your property:

They’re Built to Last for Generations: Oak’s exceptional durability means your building or structure will continue to stand proudly long into the future, becoming part of your family’s story.

They’re Naturally Energy Efficient: Oak offers excellent natural insulation, meaning an extension, garden building, or closed garage will keep cooler in summer and warmer in winter, reducing energy costs while maintaining comfort.

They’re Low Maintenance, High Reward: Once in place, your oak frame requires little upkeep. With its natural resistance to moisture and decay, oak remains stable and beautiful with minimal intervention.

They Add Value and Elegance: An oak-framed extension or garden room enhances the use and visual appeal, and therefore the value, of your home, offering a timeless feature that future buyers or renters will appreciate.

Green Oak vs. Kiln-Dried or Air-Dried Oak

You may have heard of kiln-dried or air-dried oak, but when it comes to oak-framed buildings, nothing matches the benefits of green oak. Kiln-dried oak is dried artificially to speed up the process, but this can compromise the natural strength of the timber.

Meanwhile, air-dried oak takes years to dry fully, making it less practical for large structural frames.

Green oak, on the other hand, is cut and shaped while it’s still full of life. This allows for precise joinery and ensures the timber settles naturally once installed, creating the strong, seamless joints that oak framing is famous for.

What’s Involved in Drying Oak?

Drying oak beams involves removing moisture from the wood to reduce its weight. This, in turn, prevents warping or cracking and increases overall strength. The correct length of time for drying oak beams depends on the cross-section size, initial moisture content, and drying conditions.

In general, air drying is the most common method for drying oak beams. The beams are stacked with spacers between them to allow air circulation and are left in a dry, well-ventilated area where they will be protected from direct sunlight and rain.

It’s also important to note that not every oak frame manufacturer will be air-drying their oak correctly, or for the right length of time. Some may not be allowing sufficient time for the timber to dry fully, or may even be using substandard timber that has not been properly prepared for air drying.

How English Heritage Buildings Ensures Quality Oak

Every oak frame that leaves our workshop has been carefully selected from a responsibly managed French forest site that we’ve worked with for decades. It’s then graded at our workshop and cut to perfection. We only accept timber that meets our strict standards, from its grain angle to the quality of its knots. This meticulous approach guarantees a frame that is both beautiful and built to last for decades to come.

We’re proud to be the first UK oak frame manufacturer to hold BM TRADA’s Q-Mark certification, meeting 22 rigorous industry standards. As part of this, all grading is done by our in-house team of qualified experts, ensuring it meets exact specifications for your project.

Bring Heritage Home With an Oak-Framed Building

Whether you’re dreaming of a garden room, extension, garage, or porch, our expert team can bring your vision to life with a bespoke oak frame that stands as a true piece of English heritage. Request a brochure or get in touch with our friendly team to discuss your project and discover how we can help you bring timeless craftsmanship home.

How to Maintain your EHB Oak Structure

Now that you are the proud owner of an English Heritage Buildings oak frame structure,
there are a few things you will need to consider. These considerations are important for maintaining the natural beauty of your timber building.

As your frame seasons, it will gradually lose its moisture. This will result in visual changes to your frame, and the process is particularly apparent in the first few years.

Treatment of internal oak timbers can help to limit excessive movement and cracking. Internal oak timbers can be treated with a variety of products or left untreated as you wish. External oak timbers, meanwhile, can be left to weather to a silver-grey colour.

Exposure to the elements may cause oak to bleed onto the brickwork and stones. This can leave rust-like stains, but these stains will fade in time and, if desired, can be cleaned with a suitable brickwork cleaner.

Weatherboard

Fire-Retardant Softwood Weatherboard

Your Fire-Retardant Softwood Weatherboard comes treated with SENTRIN FRX fire-retardant chemical, necessary to meet the testing requirements of BS EN13501-01:2007 fire classification of construction products and building elements.

No further treatment is needed. If you wish to decorate, please check that the product you are planning to use is compatible for use with SENTRIN FRX Exterior. Using a non-compatible product may affect the fire-retardant properties of the weatherboarding.

Oak Weatherboard

Due to its natural properties, oak weatherboard is prone to shrinking and splitting. Unfortunately, there is no treatment that can prevent this. You may also notice a small amount of mildew forming on the faces of the board.

Oak weatherboard provides the perfect conditions for mildew spores to develop due to the moisture content, which can be more apparent during the warmer months. This is a normal feature of oak weatherboard and will disappear over time, as the oak weathers, to an attractive silver-grey.

Joinery

Prolonging the Life of Your Joinery

In order to extend the life of your joinery, you can:

• Inspect the windows annually
• Repair any small patches of coating damage promptly
• Redecorate when the lower parts of the joinery show general signs of wear
• Wash it with a solution of warm water and liquid detergent
• Keep moving parts i.e., hinges, locks, handles, etc., free of grit, dirt, or mortar. Clean them regularly and apply white lithium grease for hinges and a Teflon-based dry lubricant for locks.
• Do not paint over rubber gaskets or ironmongery

Gutters and Downpipes

Cleaning your gutters and downpipes regularly can increase their life expectancy, so make sure that you take the time to properly inspect and clear them.

If there are no signs of structural damage, then a thorough cleaning should be all that is required. Cleaning your gutters twice yearly, at the end of Spring, and again at the end of Autumn, will suffice.

Here are some tips on what to look out for and what to do when inspecting your gutters during the year:

• Blocked downpipes and leaky joints during heavy rain
• Making sure gullies at ground level are kept clean
• Making sure vegetation is kept away from downpipes (this can be achieved by cutting it back or removing it)
• Fitting bird or leaf guards to soil pipes and rainwater outlets to help prevent blockages
• If your gutters are sloping the wrong way or discharging onto the wall, have them repaired

How to Clear Your Gutters

You will need to begin by cleaning any debris off your roof, using a rake or yard brush.

Using gloved hands or a small garden trowel, clear the gutters of any debris.

Flush any of the finer bits of debris down towards the downpipe using a garden hose. Ensure that water is flowing properly down the spout* when you do this.

*If you have a downpipe that is connected directly to underground drains DO NOT flush a blockage with the hosepipe.

Clearing a Blockage in Your Gutters

To clear a blockage in a downpipe you will need to take it apart, dislodge the blockage, and connect it back together.

Using a screwdriver, gently tap the downpipe where there are no blockages. You should hear a hollow sound in return. Once you have located your blockage, use a screwdriver to unscrew the downpipe clips and brackets from the wall and dismantle as much of the downpipe as necessary. Clear the pipe of the blockage and reassemble.

Remember to apply a silicone lubricant to the seals of the pieces you dismantled.

What Do We Supply for Oak-Framed Buildings?

When you invest in an oak-framed building, what you don’t see is just as important as what you do. Behind every beautifully crafted frame is a carefully specified structural system designed to perform reliably for decades.

At English Heritage Buildings, we supply precision-made, bespoke green oak and Douglas fir frames alongside high-quality, strength-graded structural timber and treated external materials. These are all selected to support longevity, safety, and peace of mind.

What We Offer You

• Structural softwood carcassing timber, supplied as standard to C24 grade
• Treated softwood weatherboard, prepared for external use
• Consistent quality control, including professional timber grading

What is Carcassing Timber? 

Carcassing timber is the structural softwood used behind the scenes of a building. While it’s not always visible once construction is complete, it plays a crucial role in strength, stability, and long-term performance.

You’ll typically find carcassing timber used for:

• Roof structures and rafters
• Floor joists
• Internal wall structures (studwork)

Because this timber supports the building structure, its strength and treatment are essential, which is why we specify it carefully.

Our Standards for Softwood Carcassing Timber

All softwood carcassing supplied by English Heritage Buildings is C24 strength-graded and professionally treated with Vacsol Aqua preservative, using a double-vacuum pressure process, to help protect it for the long term. This process is designed to support a service life of 60 years or more.

To maintain this level of protection, we also apply end-grain treatment to all cut timber before it leaves our workshop. This ensures vulnerable cut ends are protected and helps preserve the integrity of the treatment.

A Note: Cutting or machining timber after treatment can reduce the effectiveness of the preservative, which is why preparation before delivery matters.

Our Softwood Weatherboard 

In addition to structural timber, we also supply softwood weatherboard where required, treated with Axil 3000P, a water-based wood preservative. This treatment helps improve durability and suitability for external use, supporting long-term performance when correctly installed and maintained.

What Does “Graded Timber” Mean? 

Timber grading is a process used to assess the strength and suitability of timber for structural use. Grading standards are set out by the British Standards Institution, and timber is assessed against clear criteria to ensure it can safely perform its intended role.

During grading, factors assessed include:

• Signs of woodworm
• Knots
• Splits along the grain
• Grain direction

C16 vs C24 Timber

When researching a building project, you may come across references to C16 and C24 timber. Both are commonly used structural grades of softwood, but they are suited to different applications depending on strength, appearance, and performance.

C stands for “conifer”, the type of tree that the timber comes from, while the 16 and 24 refer to the strength grade. 

What is C16 Timber?

C16 timber is one of the most widely used grades in the UK construction industry. It offers good structural strength and is commonly used for internal applications such as wall studs, floor joists, and roof structures.

Because C16 timber can include more natural variations, such as grain deviations or cosmetic markings, it is typically more cost-effective. These visual characteristics don’t prevent it from being used structurally, but they do mean the timber is less consistent in both appearance and overall strength compared to higher grades.

What is C24 Timber?

C24 timber is a higher-grade structural timber, offering greater strength and consistency than C16. It is kiln-dried and carefully graded to ensure fewer defects, resulting in a more uniform appearance and improved structural performance.

This higher quality is often achieved because the timber comes from slower-grown trees, which produce a tighter grain structure. The result is timber that is stronger, more resilient, and better suited to applications where performance and longevity are especially important.

Due to these qualities, C24 timber typically comes at a higher cost, but it also provides greater reassurance when used in demanding structural roles.

Quality You Can Rely On

Every element we supply is chosen to support the same goal: to create oak-framed buildings that are built properly, perform reliably to modern expectations with traditional standards, and stand the test of time.

Our approach combines:

• Clear, upfront specification  
• Over 30 years of experience
• Professional timber grading
• Consistent manufacturing processes

Learn More or Speak to an Expert

If you’d like to explore further details or understand how this applies to your own project, you may find some of our other guides and services helpful. Request a brochure or find out what’s included in your quote right here on our website, or get in touch with us online or over the phone. 

Whether you’re planning an oak-framed garage, garden room, extension, or bespoke building, our team is here to help you move forward with confidence.

Annex 3: Normative Documents

The Standards Behind Our Oak-Framed Buildings

When investing in an oak-framed building, you want confidence that it has been designed, engineered and manufactured to last, not just to look beautiful on Day One, but to perform reliably for decades to come. At English Heritage Buildings, every oak frame we manufacture follows a rigorous, multi-point quality system. This system is underpinned by a series of recognised British and European standards, known as normative documents. These documents govern how our buildings are designed, tested, graded and manufactured, ensuring consistency, structural integrity and long-term durability.

Below, we’ll explain more about the rules, regulations and best-practice standards found in the documents, so you can feel confident and fully informed about every aspect of our process before you begin your project.

Why Normative Documents Matter

Normative documents are official industry standards used across construction. They set out how buildings should be designed, how materials must perform, and how quality is assessed at every stage.

How These Standards Protect Oak-Framed Buildings

The documents can be grouped into a few key areas that directly benefit your project:

Structural Design and Safety: These standards ensure your oak-framed building is properly engineered, taking into account factors such as weight, wind exposure and roof loads. This helps deliver a structure that is safe, stable, and designed to last.

Timber Grading and Material Quality: Oak is a natural material, and not all timber is the same. These standards govern how structural timber is graded for strength and suitability, ensuring that only appropriate timbers are used in load-bearing applications.

Quality Management and Certification: These documents underpin how quality is controlled across the entire manufacturing process, from design and timber selection through to machining and final inspection.

Thermal Comfort and Performance: Some standards relate to insulation, thermal resistance and acoustics, helping to ensure that oak-framed buildings perform well once they become part of your home or property.

As the only oak frame manufacturer in the UK to hold the BM TRADA Q-Mark certification, English Heritage Buildings is independently assessed against these standards annually.

The Rules, Regulations, and Standards We Manufacture To

Below is the full list of British, European and international standards followed as part of English Heritage Buildings’ manufacturing and quality assurance processes:

• BS EN 1995-1 Eurocode 5 – Design of timber structures.
• BS 5268 – 2 Code of Practice for permissible stress design, materials and workmanship.
• BS EN ISO17025 General Requirements for the competence of testing and calibration laboratories.
• BS EN 1990 Eurocode 0 – Basis of structural design.
• BS EN 45011 General requirements for bodies operating product certification systems.
• BS EN 45012 General requirements for bodies operating assessment and certification/registration of quality systems.
• ISO 9001 Quality Management Systems. Requirements.
• ETAG 007 European Technical Approval Guideline 007 ‘Timber Frame Building Kits.
• BS EN 13986 Wood-based panels for use in construction–Characteristics, evaluation of conformity and marking.
• ISO Guide 65 General requirements for bodies operating product certification systems.
• ISO Guide 62 General requirements for bodies operating assessment and certification/registration of quality systems.
• BS 5756 Visual strength grading of hardwood. Specification.
• BS EN 6399-1 Loading for Buildings. Code of practice for dead and imposed loads.
• BS EN 6399-2 Loading for Buildings. Code of practice for wind loads.
• BS EN 6399-3 Loading for Buildings. Code of practice for imposed roof loads.
• BS EN 120 Wood-based panels. Determination of formaldehyde content.
• Extraction method called the perforator method.
• BS EN ISO140-7 Acoustics. Measurement of sound insulation in buildings and of
• building elements. Part 7 Field measurements of impact sound insulation of floors.
• BS EN ISO 6946 Building components and building elements. Thermal resistance and
• thermal transmittance. Calculation method.
• BS EN 14081-1 Timber structures — Strength graded structural timber with rectangular cross section — Part 1: General requirements.
• BS EN 338 Structural timber — Strength classes.
• PD 6693-1 UK Non-Contradictory Complementary Information to Eurocode 5:
• Design of timber structures Part 1: General – Common rules and rules for buildings.
• BS EN 1912 Structural timber — Strength classes — Assignment of visual grades and species.

What This Means for You

By designing and manufacturing oak-framed buildings in line with these standards, English Heritage Buildings offers you:

• Clear, upfront design and engineering assumptions
• Consistent quality across every bespoke project
• Confidence that your oak frame has been independently benchmarked against recognised industry standards
• A structure designed for longevity, performance and enduring beauty

This approach also reflects our wider commitment to craftsmanship, transparency and long-lasting heritage.

Work with Experts to Plan Your Oak-Framed Building

If you’re planning an oak-framed garage, garden room, extension or bespoke building, or simply want to understand how our approach differs, our friendly team is here to help.

Explore our oak-framed buildings online, request a brochure, or get in touch to speak with an expert about your project and next steps.