During the course of my work as a Gardens Consultant, I am tasked with sorting out many problems, every enquiry varying in its’ scope, size, complexity and difficulty. This is one of the joys of the job, especially in my special niche – that of Dispute and Court work. I am totally independent, whether working on a Single Expert commission, Single Joint Expert (where two individuals pay half of my fee each and both agree to use my services) or under a Civil Procedure Rules (CPR) Part 35 Report basis, working under the instruction of a solicitor or Court. I remain 100% impartial at all times, otherwise I could not do my job.
Whilst every case is interesting, as each one has its’ own background, history, reasons for becoming a dispute in the first place, or simply the location and nature of the problem. Sometimes though, a project becomes more than generally interesting – it has a potential impact of the wider industry of Landscaping, and to have an opportunity to prevent a case from causing disruption across the country is very rare.
I have recently had one such case, and without going into detail at the risk of identifying the property and individuals involved, the project was somewhere in England, and concerned a paving contract for a large area of a garden in a private property.
It was a labour only contract, with the landscaper commissioned to lay natural stone paving, 20mm thick, in slabs of 60 x 60 and 60 x 30 to a series of multi-level terraces. The levels were retained by concrete block walls, backfilled with rubble and whatever else was on site. The owner acted as Main Contractor (which brings up another set of issues regarding CDM 2015 and attendant responsibilities. See elsewhere in The Library). It transpired that the owner called in various friends and others to carry out the construction works including a series of retaining walls, between 1.2m and 2.4m high, without any Architect’s drawings or Structural Engineers specification.
The concrete foundations over which the paving was to be laid were in situ, and the contractor did not know what they comprised of, except that they were constructed by the owner. In the event, it was discovered that the foundations have not been laid on to the walls, rather added behind them and not tied in to the walls.
The design and build element is not particularly germane to this article, but is does provide a background to the problems encountered by the paving contractor, as shortly after completing the majority of the scheme, the paving slabs became loose from their (sand and cement) laying bed, over a 100mm concrete foundation. The job was carried out in 2015/16, before slurrying the backs of slabs became the accepted practice. It is very important to bear in mind, that practices that have changed (often rapidly) over the course of a few years, should in no way condemn what was considered sound practice at the time the work was carried out.
I was called in to produce a report, and duly submitted that the paving had become loose from the laying bed – or rather, the laying bed had become loose from the slabs, as the infill material has settled due to poor construction techniques including drainage issues/total lack of weep holes through the walls etc. To be fair, whether or not the paving had been slurried would have made no difference – except that the slabs would have cracked rather than simply ‘popping’ from their beds. The difference between the finished levels of some slabs I inspected was 20mm from one slab to the next, such was the settlement over an area of 600m2. Fortunately, the contractor had kept a detailed photographic record of every stage of the project, including noting the various cracks and settlement in the foundations, which had been constructed by others
Owner blamed the Contractor – despite being in charge of the project
The owner was not happy, blaming the contractor, and engaged an Architect as an Expert Witness (despite not being a stone specialist), who produced a lengthy report, condemning the paving contractor, blaming him for the failure and ‘falling foul’ of BS5385 in laying the tiling. Notice, he did not use the word ‘paving’, but rather ‘tiling’ to describe the materials used on the project.
In this instance, the paving was sawn six sides sandstone @ 20mm thick and sold as EN 1341 compliant.
BS5385 concerns Tiling, and not paving. BS 5385 precludes any stone material over 12mm thick. The expert also referred to the material as ‘slate’ when it was in fact, sandstone, which further diminished the credibility of the report in my eyes.
The owner went to County Court, employing a number of highly paid solicitors to sue the contractor for poor workmanship. I will not go into detail regarding the case, but the most important point being made in this article, is that if the Court found that BS5385 (Tiling) was to prevail, it would mean that every stone supplier in the UK would have to scrap their laying instructions and produce fresh ones, leaving existing warranties null and void.
We have seen natural stone paving products become increasing thinner over the years. Around 2010, a ‘one ton’ crate of sandstone would hold no more than eleven square metres of paving. In 2020, that area has increased to seventeen or eighteen, simply because the slabs have been through a ‘thicknesser’, thereby reducing the previous 25mm slabs to 20mm thus increasing the metreage available in one crate.
The main message in this essay is to point out that we are getting close to a time when the old BS EN 7533-4, which is the British Standard for paying paving, will become confused with BS5385 at some stage.
Currently, there is no minimum thickness for paving slabs, but it must be twice the thickness of its’ length and a minimum of 150mm (in other words, a slab, not a tessera or mosaic piece). This paving was sold under BS EN 1341, and is a natural stone product. This paving material should therefore be laid in accordance with BS EN 7553-4.
To summarise, there are two messages here; be aware of the two different British Standards. Check them out for full details and information, including keeping up to date with any alterations that may be made, bearing in mind the changing thickness of materials.
The difference in laying techniques for paving and tiling are wide and varied. The Standards for Tiling are largely based on internal settings, and there are some instances of landscaping works that may require BS5385, for example, garden kitchens with overhead covers and requirements for a different cleaning regime that an external patio, even if the flooring materials are the same (e.g. ceramics). These tiling products may be used to clad walls, and will fall under the same BS5385 if they are under 16mm thick.
Keep records of all projects
The second message is very important. The Contractor in this case had retained a copy of the laying instructions included in the original paving packs. As methods change, as contractors, we should not be penalised at some future date simply because recommendations have altered. Whatever you do, whichever product you lay, ensure that you retain a copy of all relevant information, instructions, guidelines and product names, together with any code numbers or other details to protect yourself from future claims.
Luckily, in this particular case, the owner had engaged a Surveyor who was not as expert as he may have been, and because the contractor had been very professional and vigilant in retaining information from the project even five or six years later, the case was resolved in a satisfactory manner.
Record every aspect of a project, including those matters that may affect the success of a scheme. In this particular case, it was the failure of the builder (owner) to correctly construct the walls and foundations. Other factors that may cause concern are drainage, level and falls of any scheme where other trades are involved. Protect yourself at every stage, especially if you were not party to a construction and arrive on site after certain works have been carried out. (See Waivers elsewhere in The Library)
Alan Sargent FCIHort MPGCA
Landscape Library