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What to Consider When Seeking a Timber Expert Witness
  • Apr 11, 2023
  • Latest Journal

When a dispute arises with timber or wood-based products, whether it’s a cosmetic defect, failure which leads to shorter than expected service life or to personal injury, it’s important to consult an expert witness in timber to provide good, clear judgement on the case. Phil O’Leary, Technical Manager at BM TRADA, explains what to consider when looking to appoint an expert witness.

Timber, with its impressive environmental credentials, is becoming a popular material choice in many industries. We need look no further than the construction industry to see this. The demand for wood products is increasing rapidly across both the residential and commercial building sectors given the material’s sustainability and carbon capture benefits. Moreover, it is fast to build with, and a study by MTW Research found timber frame housebuilding was expected to see a £70m increase in 2022, while the sector is projected to increase by over £150m by 2026.

However, the more uptake there is in the use of wood, the more opportunity for poor specification, utilisation or construction by unskilled or untrained operatives. In turn, arguments over accountability will naturally arise, and liability claims and cases are all the more probable, especially when wood is now being used on large-scale structures and developments and for an increasing range of products. Indeed, there are many cases of timber failing to perform as designed or intended for various reasons. These range from roofs to floors, retaining walls to scaffolding boards. The latter has led to personal injuries and accidents, whilst others have often resulted in costly remedial works and prolonged delays in build programmes.

That said, the causes of failings in timber structures or products are typically triggered by a combination of one or more of the following: quality of material, poor design and specification, poor installation and erection practices, and workmanship.

Employing timber expert witnesses – what to consider
Given the significant impact and consequences of timber failures, determining who is at fault is often a crucial point when it comes to disputes. If disputes result in litigation, the importance of employing an expert witness in timber is key.

At this juncture, there are a few key points to bear in mind. This includes having knowledge and experience in wood as a raw material, to wood processing and specification, through to familiarity with legal processes and service capability with investigation and document review. It’s worth noting that this is a highly specialised field, with wood and timber experts with the appropriate understanding in these areas is few and far between.

All about experience
First and foremost is the aforementioned experience of working with wood. Even without taking into account human error with design and construction, wood is one of the most complex building materials in use. From hardwoods to softwoods and the various panel products such as plywood and particleboard, and the engineered solutions such as I-joists and cross-laminated timber (CLT), there are many different species and products which are in use today. Comprehending how these different types and categories work and interact is crucial in a dispute. A good understanding of European and UK Standards and product standards is also crucial.

In cases where expert witnesses are involved, often there will only be one or two experts that are appointed to provide their judgement on the case. This is typically one expert witness employed by each party, or one acting on behalf of both sides (an important point to know here is that an expert witness’ duty is to the court, not to the party that appoints them). However, even with this, consider whether that expert that can call upon other timber colleagues who may have their own specialisms in timber and their professional experiences and opinions. For example, BM TRADA has experts in various fields of timber with many years of experience, who are members of various standard and technical committees both at National and European level, of whom can pool together to support in a case.

Also look at what resources the expert has available to them to help undertake any investigative works. For instance, laboratory examination and testing, and the resulting gathering of data and evidence, are often important to accurately determine the timber defects and causes. This is why BM TRADA holds samples of many wood species in its conditioned timber specimen library (also known as a xylarium) at High Wycombe, UK and has a dedicated Timber Technology Laboratory. This facilitates easier laboratory and examination, especially when looking at assessing not only rarer varieties of timber but also the construction and make up of products.

Using sight, on-site
As well as laboratory and personnel capabilities, often, site assessments will be necessary. Here, having an expert witness who has the right tools and instruments to analyse and assess defects, together with the know-how of where to look, is a major point of difference. Quite often, a timber expert witness will need to go to site and deploy their skill and experience in gathering evidence and data.

Being able to test for fungal decay and rot, wood preservation, condition of coating and finishes, strength grading of structural timbers, identify insect and causes of staining, and assessing detailing and construction of timber elements are also skills often required of a timber expert witness. Meanwhile, evaluating structural connections for strength and design is another facet of a timber expert witness’ job.

Looking at legalities
While all of the above tests an expert witness’ competency, something that cannot be overlooked during the selection process is their familiarity with the legal processes, and, most importantly, how they cope when cases go to court.

There are a number of proceedings prior to this stage. This includes document reviews, exchanges with opposing expert witnesses, and preparing Part 35 Expert Witness Reports to submit to court.
Should a case not be settled outside of court, expert witnesses will likely need to attend court and testify to statements made in their reports. At this point, having a professional with good detail orientation and the experience of handling these occasions is a must. As can be expected, any mistakes over statements when facing barristers can be very costly and will weaken a case, as well as undermining authority on the matter.

Where to look for an expert witness in timber
While times have certainly moved on from directories and there is an abundance of ways to search for an expert witness, quite often, the best starting point is checking the Expert Witness database. Beyond that, check that the expert witnesses you have shortlisted are part of The Academy of Experts, which BM TRADA is a member of. This is an independent professional society and accrediting body for expert witnesses.

By having an approved expert witness, grey areas on disputes and cases can be prevented, and parties can better understand if they have a good case to go to court or reach the settlements they are asking for.

For more about BM TRADA’s timber expert witness services, please visit