Roof Slates Melting in the Sun

A manufacturer produced an imitation Welsh roofing slate using slate particles bonded together with resin.  The manufacturer had the product independently tested by a reputable independent body and published the results.  The tests showed his man-made slate to be a serviceable product.

In time failures became apparent.  Initial inspection of one poorly performing roof showed many slates to have concave curves, and the tiling to be loose.  It was decided to re-roof with the same materials, which the slate manufacturer agreed to provide free of charge. 

The remedial work commenced in early summer. 

An Adjudicator Takes Advice Which He Does Not Follow

An adjudicator telephoned an expert to ask about the correct method of constructing a sand-and-cement floor screed.  The case the adjudicator was considering involved the incorrect placement of a reinforcing mesh in a screed. 

The expert described to him the alternatives which would have ensured correct construction.  The expert gathered from his conversation with the adjudicator that the mesh was generally laid below the screed but was in some places poking out from it.  No other fault was reported.

An Arbitrator Takes Advice

Ordinarily a tribunal – whether judicial, arbitral or adjudicatory – may obtain technical advice at need through the appointment of experts.  In this way, the tribunal need not contain members who are personally familiar with all aspects of the type of construction which is in dispute.  Expert witnesses may assist the tribunal properly to understand the technical matters they are asked to decide.  Expert witnesses are distinct from witnesses of fact in that they are allowed to provide evidence of opinion. This may involve interpretation and reliance on hearsay.

Arbitrators and adjudicators have taken expert advice outside the formal boundaries of the tribunal over which they preside. This happened quite recently where an arbitrator, outside the hearing, telephoned an expert for technical advice.

Defects often arise because the designer focuses on the finished product to the exclusion how it is made

It is fundamental to good building practice that the design takes into account the process of construction.  Concrete, for example, is unlikely to be built as a monolithic mass.  Each part of a concrete structure will be limited to that which can be built in a single working day.  If the inevitability of day joints is considered in the design, their effects on strength can be controlled.  It is less certain that their effect on the watertightness of the concrete can be controlled, but good design – which takes into account construction techniques – can greatly reduce the risk of impaired performance.

Good communication between designers and building workers helps to resolve problems.  Some designers’ lack of practical knowledge is all too apparent to site staff when they are asked to work from ill-conceived drawn details.  This encourages building workers to pay scant regard to detailed designs and to implement their own ideas of how to build, working round what they see as bad designs rather than discussing them with the designers.  This is particularly common in design-and-build contracts where the builder stands to gain no contractual advantage from drawing attention to design defects.

During an investigation of a dispute between a Dutch contractor and manufacturer over a new partly built factory, the project engineer’s drawings were studied.

Trying the Expert

As many practitioners know, disputes rarely go the distance limiting opportunities for expert witnesses to speak before a tribunal. For over 2 decades it has been my experience that well presented evidence helps to bring disputes to a close without the need for a hearing. But recently I found myself presenting evidence under cross-examination in the Technology and Construction Court twice in quick succession.

The first dispute arose out of deficiencies in underpinning and other works carried out in breach of a party wall award. The second was a dispute over the quality of built work - mostly various pavements.

In each case, I, an architect, was ranged against engineers. In both trials the opposing barristers sought to dismiss my evidence not on its merit but on the presumption that an architect is no expert in building technology. Some may suppose architects do no more than visualise concepts (or ‘colouring-in’ as some colleagues put it) but I was more than happy to be put to the test and demonstrate that we know whereof we speak.

Piling into brown fields

the drainage connected to the buildings stays in place as the ground settles exposing once flush gulleys

Building and ground part company as voids form between ground and undersides of ground floors

  Horizontal fissures forming over d.p.c.'s as brickwork bows and arches

Brickwork over d.p.c. sliding out at external corners with stepped cracking below

Fissures running between window and door openings in brickwork

 

Near vertical cracking close to corners

Dry lining being torn apart as the masonry fractures

Building over deep landfill can be perilous.

If the piles work, the buildings stay up as the roads paths and gardens settle.

Long piles can settle and deflect unevenly causing enough differential movements to crack rigid superstructures, jamb doors and windows and tear internal wall linings.

Adding to this site's troubles, brickwork without any movement control joints adds another cause of cracking.

extensions on conventional concrete rafts float away with the sinking ground tearing themselves off the piled buildings

Defect free building is as much a matter of understanding client goals as it is of achieving competent detailing and construction

The Brief
A successful project starts in good co-ordination and the development of an effective brief.  Briefs evolve with