Lifting And Re-Laying Failed Patios

As expert witnesses, we are in the privileged and unusual position of seeing failed paving projects (as well as many others involving artificial grass and decking) from the beginning – the initial complaint, through the Court’s procedures and aftermath of a case from both sides of the dispute, and very often, through to the remediation of a faulty scheme.

To be clear, we are totally independent, and are bound under strict regulations to remain impartial at every stage, although on occasion, the Court will instruct us to offer advice and make recommendations for remediation to assist both Parties in their search for a solution.

As there are many scenarios that present themselves, and each has a potentially different angle from which the case should be approached, it would helpful to illustrate some of these likely scenes.

A patio that has failed through lack of proper foundations.

Once again, there are a number of patio styles, each with their own potential issues. For example, a raised patio supported by a new retaining wall, infilled with hardcore, MOT Type 1 and laid to sandstone random rectangular slabs 20mm thick over a 30mm laying bed.

The patio has subsided inside the area of the raised mezzanine, due to the lack of adequate compaction of the sub-base material, because the contractor was frightened the wall could not withstand heavy vibrations and compaction without causing damage. Most of the paving had become de-bonded from the laying bed a) due to lack of adequate primer, b) and/or voids within the laying bed c) and/or settlement under the slabs. Any one or all of these defects could have caused the problem in the beginning by allowing water ingress.

The only possible recourse would be to take up and either re-lay the existing slabs, if they were deemed acceptable by the customer, or replace them with new. The whole of the sub-base would require recompacting and probably a concrete raft laid as a new base, reinforced to ensure that further subsidence could no longer take place. Remember – the customer is now actively looking for defects and movement in everything you decide to do.

The new project should be priced and treated as a new specification, not a simple lift and re-lay, even if all of the slabs are salvageable. Any slight damage to the slabs risks them being rejected by the client as defective. It cannot simply be lifted and re-laid over a similar bed as the one that has failed as that would not prevent further issues.

Similarly, a patio that has failed due to lack of adequate depth of excavations, membrane and MOT Type 1 will need to be lifted and re-laid with all of the attendant costs involving in lifting, cleaning, storing and checking the existing slabs for any defects, fissures, cracks etc, before any new construction works can begin. This may require off-site storage if space is limited, with attendant costs to be charged for, which will involve a two-way trip.

Your terms of reference within the quotation (not Standard Terms & Conditions) will need to reflect the costs involved, and it may in fact be less expensive to use new materials throughout, as you will be unable to offer any warranty in respect of materials you have not sourced and supplied. The customer will need to be appraised of the situation and offered a choice of reusing the old paving or paying for new before the contract is signed.

A request for a Lift and Re-lay due to unsatisfactory design issues

These cases are difficult to assess, as an expert witness. A recent case involved a large patio laid to sandstone, which had been lifted and re-laid by a second contractor as the customer was unhappy with the number of loose slabs due to lack of bridge bond slurry. The whole laying bed was full of voids, with ants and soil creating an unsightly and dangerous walking area with multiple trip hazards.

The new contractor was called in with specific instructions and brief to lift and re-lay the paving to ‘levels and lines’.  The existing paving had been laid in a traditional random rectangular pattern, and the contractor duly lifted and stored the paving on site. There was no cleaning to be done as there was no bonding material used.

As the works progressed, it became clear that some of the slabs had been sawn down to suit a particular slot, or slightly shaved to create a uniform pointing gap. Instead of rejecting these slightly misshapen units, they laid them as they saw fit, trying to jiggle them in.

The end result was a number of lines that were ‘bent’ or out of true with the remainder of the project, creating an illusion of dips and areas that were not as ‘level’ as they should have been. An optical illusion in fact, when the site was laid to reasonably accurate falls.

Other ‘defects’ that were not in keeping with the brief of laying to levels and lines, due to the shortage of available paving – instead of importing fresh/second hand stone, they created a number of straight lines within the pattern, moving away from their brief to lift and re-lay to the same random rectangular pattern.

The work was fine, all the slabs were securely fixed into their beds, with no voids or loose units, but because the contractor had not met their brief, the customer demanded a new patio, recognising that the existing slabs could not now be lifted without breakages.

This left the contractor in an impossible situation. Having made a good job of a poor one, and saving the customer money, by failing to register the importance of their original brief, they had become liable for damages and restoration.

So many times, attempts at lifting re-laying projects, whether paving, artificial grass or decking, will result in unforeseen problems, as each new element becomes exposed, new issues arise that will affect the efficiency of a contract.

For this reason, although there is a huge opportunity to gain high quality work by remediating failed projects, ensure that you protect yourself with clear documentation and detailed contract specification in your bespoke contracts.

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