BM TRADA's experts offer a range of specialist independent condition and structural surveys of timber components, across a diverse range of new and existing buildings and structures using non-destructive test methodologies.

Our findings display information on the location and extent of any biological degradation and/or any timbers that may be at risk in the future, as well as assigning a strength class to individual timber members where necessary.

We regularly carry out timber condition and structural inspection surveys looking at the condition of the timber on buildings ranging from modern timber frame housing developments to historical and listed buildings.

We also inspect infrastructure ranging from the railway and telecommunication towers to marine components and their various applications.

The timber condition and structural surveys are carried out by highly experienced timber and building consultants. We can also provide independent laboratory testing on timber specimens.

About condition and structural surveys

Condition and structural surveys are carried out to assess and advise upon a range of issues:

  • Determine condition of existing structure
  • Strength of individual timber members - in situ visual strength grading
  • Possible remedial solutions
  • Alternative use of a building
  • Preservation of historic structures
  • Compliance with codes and best practice
  • Restarting timber frame projects
  • Fire damage
  • Flood damage
  • Warranty claims
  • Concerned occupants
  • Asset management plans.

Clients we have provided condition and structural surveys for include:

  • Local authorities
  • Housing associations
  • Property developers
  • Nuclear and railway industries
  • Structural engineers
  • Architects
  • Facility management companies
  • Warranty providers.

Your structural timber FAQs answered

Wood is a natural material. From growth to use, its structural properties are highly variable as a result of several influencing factors. The effects these factors have on the structural properties of the timber section proposed require careful consideration.

If you cannot find the answer to your query in the FAQs below, please contact our free Timber Technical Helpline (Mon-Fri 9-5pm) on 01494 840 349.

Yes. The strength grading process, both mechanically and visually, takes no account of the end use of the timber.

Many of the softwoods used for structural purposes, such as European redwood, will nearly always contain a significant amount of sapwood as the trees are small in diameter.

Sapwood does not affect the strength, but only the durability of the timber. Preservation treatment is therefore an important consideration.

Glulam is a high-performance product for structural engineering manufactured from layers of parallel timber laminations.

Benefits of glulam

  • Aesthetically attractive structural timber components of large sizes and complex shapes.
  • Generally stronger than the timber from which it is made because defects, such as knots, splits and sloping grain, are randomly distributed throughout the component or simply excluded.
  • It has a high strength-to-weight ratio that makes it easy to handle.
  • It will usually have better dimensional stability and suffer less from shrinkage and deformation than equivalent solid wood sections.

For more information on glulam, its properties and uses, see the BM TRADA Wood Information Sheet Glued laminated timber.

CLT panels are manufactured by assembling layers of wood laminates (typically spruce) together, each layer being laid at right angles to the previous layer.

The structural benefits of CLT are many and include the following:

  • High axial load capacity for walls due to the large bearing area.
  • High shear strength to resist horizontal loads.
  • Dead weight reduces the need for mechanical holding down to resist overturning forces.
  • Buckling in the plane of the wall is unlikely, except for isolated columns and piers.
  • Contributes to fire resistance.
  • Shallow floors.
  • Structural fixings are easy to provide and likely to achieve their design capacity.
  • Few defects due to the inherent robustness of the panels during transport and construction.
  • Enhanced airtightness.
  • In some situations, second fix items and cladding can be fixed directly to panels using lightweight power tools.

Comprehensive information on CLT, its properties and uses, can be found in the BM TRADA Wood Information Sheets Cross-laminated timber: introduction for specifiers and Cross-laminated timber: structural principles.

Although softwoods have largely displaced hardwoods as a structural material in modern construction, hardwoods are used for specialist engineered products including glued laminated (glulam) and mechanically laminated (mechlam) timber, and for particular end uses where their high strength and durability is vital, such as marine structures and sea defences.

When compared with structural softwoods, hardwoods in the medium-to-high-density ranges have:

  • greater strength and stiffness
  • availability in longer lengths and larger sections
  • higher density, generally giving superior fire resistance
  • greater natural durability in most species
  • more varied aesthetic appeal as exposed members.

Guidance on how to specify hardwoods for structural use can be found in the BM TRADA Wood Information Sheet Structural use of hardwoods.