The Expertise of an Expert Witness

What does it take to be an expert witness?

An expert witness duty is to the court and not the client.

An expert witness duty is to the court and not the client.

I’ve been doing expert witness work and writing part 35 compliant reports for a number of years now relating to construction defects and disputes between landlord and tenant, the latter cases usually related to damp and mould. However, we’ve had two cases relatively recently that have led me to carefully question any potential case that comes in. When it comes to this work I’ve always limited myself to my particular area of expertise, which broadly speaking is building pathology, however, through the course of doing this work I’ve come to realize that many surveyors are simply expert at being an expert. What do I mean by this?… Quite simply I’ve found that  often any expert acting on behalf of the other party often has no expertise in building pathology, rather they have a knowledge and expertise in producing part 35 compliant reports and a knowledge and understanding of the civil procedural rules and often they’ll act in any case as expert witness, irrespective of the matter under dispute. The last time the opposite party insisted on appointing his own surveyor at great expense, the net result was that his surveyor simply indicated to me that he agreed with everything I’d reported and discussed on site. What some clients simply don’t get is the impartiality with which one has to act as an expert witness and on that occasion the other party could have saved himself a great deal of money. I would generally advise all parties to appoint a single joint expert, rather than insisting on their own, because it simplifies and streamlines the process and makes it far more cost effective.

But what if the expert favours one party?

I live in the real world so I won’t pretend this can never happen, but quite simply it shouldn’t! So long as both parties do their research and jointly agree that the SJE has the relevant expertise and has no conflict of interest then a single joint expert should always be your preferred option. Returning to my earlier point on expert experts, remember to make sure that expert actually has a focussed area of expertise related to the matter in dispute, as opposed to simply understanding court procedure.

What does expert witness work involve?

What I’ve come to learn over time is that acting as an expert witness is incredibly time consuming. It starts with a desktop review of all relevant paperwork and any relevant findings from that desktop review need writing up. Then of course there’s the site investigation work and whilst you may think that all these cases must be technically complicated, that isn’t the case at all, they have the same frequency of simplicity or complexity as any other case we work on, some cases being so simple that you question how on earth a dispute ever arose.

Needless to say, the final reports can be quite lengthy, our reports are generally more than thorough but any expert witness report we produce has to be as detailed and extensive as the facts require it to be; always of course remembering that the courts will be using the final report to enable them to reach a decision. I always retain a view that non-technical legal experts have to understand the technical issues and so reports are always heavily illustrated to facilitate that requirement.

Even on production of the report, the work doesn’t necessarily stop there because occasionally the opposing parties will then come back with a series of questions or clarifications required, which have to be answered.

The dark side of expert witness work

On a relatively recent case I was involved in for a client in the northwest, I reviewed the initial evidence informing my client that on paper he didn’t appear to have a strong case. Nevertheless I was appointed and completed a detailed technical report relating to water ingress in my clients garage. His view being that it was caused by the neighboring garage, whilst of course, his neighbor disagreed. In fact, it was my own clients defective parapet wall that was to blame and the case was proven unequivocally, to the extent of photographing fluorescein dye running in from the parapet wall during a hose test I carried out. Of course I fully expected this because the visual defects were obvious.

On completion of the survey I had a conversation with my client and solicitor at the property and I remember my client stating, “so I’ve paid you for nothing then.” Well actually no, I replied, you’ve paid me to correctly diagnose the defects to enable you to cure the water ingress. I could tell my words didn’t hit home but as any surveyor involved in expert witness work will tell you… sometimes it isn’t about the facts, it’s about the people!

What subsequently transpired was that over a 4-6 week period I was bullied and cajoled by my clients solicitor to change the contents of my report to indicate that in fact the neighbor was responsible; something which I refused to do.

Several months later the client placed a complaint asking for a refund on the survey fee on the basis that it was wrong. This was refused because it was not just factually correct, it was wholly objective and based on proven facts. I was fully confident that no one would counter or overturn the content of that report.

We later found out that the client never used the report but in fact made claims to the other parties solicitor that the report wasn’t ready for the court date as we were changing the contents to indicate that the other party was responsible, something we’d flat refused to do.   Incredibly the other party settled out of court based on this claim. Something confirmed after a conversation with the opposing solicitor. When my own clients solicitor was made aware that I was aware of this fact, the claim for a refund was dropped, though with further veiled and empty threats that should the decision be overturned then we’d be ‘pursued’, whatever that meant.

Three years ago we acted on behalf of a contractor in a similar dispute that involved failure of a calcium sulphate floor screed in a children’s nursery in the West Midlands. The client initially describing the finished report as ‘excellent’ but sending it back to us for a complete rewrite several weeks later when senior management realized that our conclusions meant they’d be responsible for tens of thousands of pounds worth of remedial works. Yes, incredibly our report was returned with several sections re-written with a casual comment that we ‘sign off’ on the changes. Again we refused and were left with a final comment that, “you’ll never work for us ever again.’ A decision we’d already made when we were asked to make those changes. Now don’t let either of these examples lead you to believe that we never find facts in favour of our own client when not acting as SJE, because we frequently do, but we find what we find.

The moral of both these stories is don’t appoint an expert and expect him to act in your favour! When not acting as single joint expert (SJE) I make a point now of explaining to all clients that the technical facts may not necessarily come out in their favour because as an independent expert, our duty is to the court and not to the client!

Fact Vs Opinion

It may surprise you to learn that there is rarely expert opinion in any of the reports we produce. We focus on detailed survey work and collecting objective evidence and therefore all our reports are based on objective facts rather than subjective opinion. Often a huge amount of research goes into linking particular defects with the relevant construction standards so any ‘opinion’ given is based on those standards; if the opposing party disagrees, they are not disagreeing with me, they are disagreeing with recognized British and European standards. On a recent long running case for a client in the East Midlands, the opposing parties expert disagreed with my view that £40k’s worth of timber windows were not fit for purpose. One of the key technical issues being that there was no gradient to the head of the windowsill; not required said the opposing party. Some research later and I provided the information from BS644:2009 which, states that window sills should be, ‘angled with a slope of not less than one in eight ( 7 degrees). As always, fact and research won the day.

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Timber Frame Defects

Common Timber Frame Problems

Neo-Georgian with Timber Frame

Neo-Georgian with Timber Frame

We were recently called to investigate some damp and structural issues to a 12 year old timber frame Neo-Georgian 3-storey apartment block across the water from mainland UK. The building had been affected by both water ingress and a number of structural issues for quite some time and two previous technical reports had reached broad agreement of the fact that the timber frame was showing signs of distortion due to shrinkage, shrinkage commonly occurs in timber frames after construction and one engineer estimated the height of the timber frame may reduce by up to 30mm, a degree of shrinkage that wouldn’t be replicated in the outer non-structural leaf of masonry. In fact the outer masonry leaf tends to expand as it takes up moisture during the first couple of years after construction, so it is in fact moving in the opposite direction to the timber frame.

Wall Ties

It is for these reasons that timber frame movement ties are specified for developments over four storeys, as these are required to accommodate the additional vertical movement in the timber fame and differential movement between the inner and outer leaf. However, this is a 3 storey development and so long as vertical movement stays within expected limits then a standard fixed wall tie should suffice.

Standard Timber Frame Wall Ties

Standard Timber Frame Wall Ties

Timber frame movement tie

Timber frame movement tie

 Structural Cracking & Movement

Significant structural cracking

Significant structural cracking

Structural cracking to the outer masonry leaf of timber framed buildings can often occur where this differential movement between the inner and outer leaf falls outside of acceptable limits due to inherent design flaws or poor build quality.

When inspecting the building externally we noted that door and window frames were often slightly deformed and out of square, which resulted in extreme difficulty in opening the softwood timber french doors leading out onto the apartment balconies. We also noted significant stepped cracking in a number of areas to the outer leaf of masonry.

Starting from the Top

It was initially thought that defective balcony detailing and waterproofing arrangements were the cause of water ingress into the building and in fact the initial instruction was very much about investigating potential balcony defects, but of course you must approach these investigations with a blank canvas and an open mind. Whilst there were a number of relatively minor issues with balcony upstand detailing and parapet wall box gutter outlets, it was clear that these were not responsible for the water ingress or the structural defects seen.

Logically, I like to start from the top and work my way down once I start the internal inspection  and starting from the top meant inspecting the balcony that fully surrounded the building at top floor level.

Keeping the Timber Frame Dry

Open bed joints to parapet copings and no throating detail to underside

Open bed joints to parapet copings and no throating detail to underside

I found a number of serious and critical defects relating to the high level parapet walls that in my opinion have been allowing rainwater ingress into the wall cavity for a number of years, possibly since the building was constructed. Of course, if this was the case and water ingress was as bad as I believed it to be then the the greater probability is that the timber frame has swelled and expanded, rather than shrunk. The net result of course is the same, which is the potential for excessive differential movement between the inner and outer leaf. Moreover, there is a further potential for timber decay in the structural timber frame and perhaps even structural failure as timbers are affected by fungal decay.

Open perp joints between coping stones

Open perp joints between coping stones

Defects Causing Consequential Damage

Adhesive and cohesive failure of sealant to coping bed joint

Adhesive and cohesive failure of sealant to coping bed joint

We noted that the parapet wall copings were not fit for purpose and had been poorly installed off centre so the outer wall face had a 70mm overhang, whilst the inner parapet wall face only had a 30mm overhang. To meet the requirements of BS5642 then a minimum 45mm overhang was required to either side. However, more critically there was no throating detail to the underside of the parapets meaning that rainwater would flow along the underside of the coping overhang and straight into  cracks or open joints that may exist to the coping mortar bed.

Lead apron proved not to extend across the width of the cavity

Coping stone removed. Lead apron proved not to extend across the width of the cavity

 

Of course, this shouldn’t be a problem, because there’s bound to be a physical damp proof course installed under the copings as a secondary line of defence… or at least there should be!  We removed a parapet coping and as we suspected there was no physical DPC installed. So water was entering the wall cavity from the underside of the failed bed joint to the copings and the open joints and cracks in the coping mortar perp joints.

On finding these defects we of course had serious concerns as to what effect this long term water ingress was having on the timber frame. On checking the timber moisture content to the head of the timber frame we recorded a moisture content of 21.2%, proving the real current and ongoing risk of timber decay to the structural timber frame.

High moisture content to timber frame

High moisture content to timber frame

 

 

 

 

 

 

 

 

We recommended and specified urgent works to correctly waterproof the balcony parapets and further recommended opening up sections of the wall cavity where cracking had occurred to inspect the integrity and condition of the structural timber frame.

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