Oak Structures

There are few people in the UK who are qualified to grade hardwoods, yet Structural & Civil Consultants has a Certified Grader who is also a senior Structural Engineer.  There are advantages in having timber officially graded, but timber can be employed to its optimum if members can 

be specifically graded for a particular use, even if that lies outside the scope of the British Standards.

 

 

The Conservation Officer was keen to preserve the existing floor of a Listed Building yet the client wanted to use both the upper and lower floor as a wine bar with associated commercial loading.  Green oak beams were used to provide additional support to the original floor and detailing allowed for subsequent shrinkage.                                                                                                                  

 

The design for a suspended café floor in Masham allowed for shrinkage in 250mm deep green oak beams with a design based on the Medieval techniques that do away with joists.  Oak floorboards on ply were laid over the oak beams at 1m centres.  This approach cost a fraction of the original concept that had priced oak flooring sat on precast concrete deck units.

The practice often designs timber trusses with spans up to 6m.  While the Victorians often used king post trusses to allow slim softwood to be used, we often use chunky oak members for aesthetic and practical reasons.  This reduces stresses at joints and allows for easier detailing of mortice and tennon connections.  Where members are constructed of green oak there are also advantages of returning to the earlier simple forms that have no internal diagonal truss members that would be susceptible to distress as the timber shrinks.

Courtyard Development for Swinithwaite Hall (Scheduled monument)

This innovative design used local beech as the main structural component. S&CC Ltd were able to use their expertise on British hardwoods to advise on the properties of beech. The timber cures more rapidly than oak, but is relatively stable if stresses are relieved as it dries. Since beech is not durable, its use was combined with external oak posts and weathering strips.

Danby Visitor Centre, The Moors Centre

Structural and Civil Consultants ltd acted as the main structural engineer for the innovative Showcase Area of the Danby Visitor Centre, alongside the architects WM Saunders Partnership ltd.

The North York Moors National Park Authority set out to construct an environmentally friendly building within what was once an old walled kitchen garden. Scrapping the proposed sedum roof and replacing the steel frame with locally-sourced timber met the client’s needs and also gained them a certificate from GreenBeams for safe carbon storage.

Oak Frame Building

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Oak frames can be used to provide some of the structural stability using knee bracing, in a similar manner to steel portal frames.  Moreover, bracing has also been found to improve the aesthetics. However bracing can complicateconstruction and the joints can be ineffective, unless correctly detailed. Great care is required when working with green oak to consider how major shrinkage of the timber will affect the building after a few years.

 

Eaves Connection. Note that the critical structural joint is moved inboard clear of decay from the key leak zone. 

 

 

 

 

  Pre-construction of key joints.

  

 

Askham Bar Terminal, York

This exceptional landmark building forms the central hub for a major new transport interchange in York. Indeed Askham Bar is already being studied by students for its innovative design.

The most exciting aspect of the project is the integration of engineering and architectural design to create a prominent state-of-the-art, negative-carbon structure. The main element in the construction was timber, which presents novel challenges for engineers.

Less obvious innovation in the civil engineering design was needed because green timber was used, rather than laminated members. The engineers also had to devise a solution for supporting the substantial weights of 250mm deep chunky green timber.

The superstructure was also designed to have a low-carbon footprint at the point of construction. The main structural components of British Douglas fir were designed to maximise the mass of sequestered carbon and to minimise the carbon footprint. Moreover, the design had to overcome the challenges associated with a landfill site above 10m of domestic refuse and the attendant risk of methane emissions this produced.

The new interchange offers substantial park and ride facilities with up to 1000 spaces. The hub itself is carefully designed for the comfort of users, with a rain- protected area to board buses, an internal waiting hall, a security control centre and meeting room facilities. The site design also anticipates any future additions such as wind turbines and generators, with the robust design intended to prevent the need for a new piled base each time a new turbine and tower are needed in future.

This project expanded on the expertise we acquired when working on the Sunderland Transport Interchange, which has subsqeuntly demonstrated the fitness for purpose and longevity of timber as a primary material. 

Askham Bar recieved a certification of 'very good' from BREEAM, the world's foremost environmental assessment method and rating system for buildings. 

  

Award Winning-I. ICE, Smeaton Award 2015 - Certificate Of Excellence