When considering a new build, it is easy to only think in terms of oak timber frame vs softwood timber frame. However, the two are not mutually exclusive and are often both incorporated into the same structure. Both have properties making them a desirable choice for specific aspects of timber frame houses. With any house building project, having a clear plan of the type of finished structure you are aiming for is important. This can then be discussed with your timber frame company and the best timber for the project (or elements of it) decided together.
Similarities Between Oak and Softwood Frames
Regardless of whether softwood or hardwood is used, timber frame construction methods are the same for both. A masonry or concrete plinth will be needed as a foundation to avoid contact between the timber frame and the ground below. The frame will then be constructed on top and when complete wrapped in a weatherproof membrane. This can then be covered with the desired cladding finish of masonry, brick, render, metal or timber. For exposed oak frames, individual SIPs or other airtight insulation materials are used to infill cavities then rendered. While individual prepared timbers can be delivered for a stick build, this is laborious and time consuming. As a result, the money saved is often not worth the effort and the skills required beyond the scope of non – professional builders. More often, the frame sections will be assembled off site by the manufacturer and delivered ready for construction. These timber frame kits can then be speedily erected and weatherproofed, allowing interior work to begin. Timber frames of any type aid insulation compared to steel or other synthetic materials and damp courses are not needed. As a natural material, wood has a minimal environmental impact during its production. No harmful chemicals or air pollution result from its use and responsible forestry management guarantees sustainability.
Differences Between Oak and Softwood Frames
Hardwoods are derived from slow growing broad leaved trees that take longer to reach maturity and the size required for construction timbers. While this slow growing confers a greater density and strength to the timber, it is less readily available, driving up the cost. Softwoods are harvested from quick growing conifers with a less dense structure making them easy to prepare and quickly available. This makes them cheaper, but they lack the durability and longevity of hardwoods. As a result, they will need to be replaced sooner and many users would rather pay the higher price for hardwoods for their greater durability.
2. Water Resistance
Due to its dense structure and high tannin content, oak is remarkably resistant to water absorption. This makes it a perfect choice for exposed frames and outdoor buildings as it needs no weatherproofing treatment. This is one of the main reason’s oak has such a long history as a construction material, particularly in the damp climate of Britain. If softwoods are used for outdoor applications, they will need to be treated to withstand water and weather damage. This will need to be reapplied at regular intervals, costing money and time spent on maintenance. Even with this extra care, softwoods will still have a shorter service life than oak.
3. Resistance to Pests
Oak is famed for its resistance to pest infestation and fungal attack. The tannins present in the wood make it unappealing and in many cases actively toxic to many pests. While prolonged exposure to damp can lead to damage from dry rot, this is rare and far less common than in softwoods. While many softwoods used for timber frames are treated with biocides to minimise damage from pests, they are still more susceptible than oak.
Oak has a distinct look, with prominent grain structures and a warm, honeyed colour making it an attractive choice for interiors. When used outdoors, over time oak develops a silvered, weathered look that fits in perfectly with natural features. The original colour can be retained using clear wood preservative and UV protection oil, but this will need to be reapplied each year. Obviously if the owner plans to paint or stain the interior woodwork softwoods may be a cheaper alternative as the wood itself will not be visible. It is also possible to use softwoods for a hidden main structural frame and accentuate this with oak in the living areas. Similarly the addition of oak features such as an extension or decorative porch can enhance an otherwise plain home. This can significantly lower the cost while keeping the visual impact of an oak frame and beams within the home. Softwoods can also be used for hidden beams or floor joists within a stronger oak frame to reduce costs.
As oak timber ages and dries out, it shrinks radially across the grain leading to splits along the timber. This does no harm and does not reduce the strength of the timbers as the splits do not cross the grain. Competent designers will incorporate this into the design so it does not affect the structural integrity of the building. In an oak frame, the tenon and mortice joints are slightly off set with solid kiln dried oak pegs connecting them. As the oak shrinks the joints pull closer together and tighten around the pegs making the structure more secure over time. This gives an aged, rustic look that many owners find attractive. If a cleaner, flat look is desired, softwood can be used for interior finishes while retaining the superior strength of the oak frame.
Hardwoods Group operates the largest 6 axis computer aided CNC machine for solid timber in the UK today. Capable of machining timber up to 13 metres in length to tolerances of just 1mm, we produce oak framed buildings to exacting specifications. Along with our range of oak framed buildings, we also specialise in bespoke structures for customers with a unique project in mind. Contact us to discuss your plans and we help to make them a reality.
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