Falcon Roofline — Sika Trocal Roofing Replacement

Falcon Roofline - Sika Trocal Roofing Replacement

Falcon was contacted by System Devices Ltd in Runcorn, Cheshire, after their local maintenance contractor came across our work in Warrington town centre passed our details over. Despite the roof covering being as old the industrial unit at circa 30 years, we were able to confirm the current covering as a Sika Trocal Roofing system, with an 80mm warm-deck insulated build-up, mechanically fixed into a 0.7mm steel roof deck.

As always, Falcon carried out a flat roof survey, enabling us to understand the reasons for the ultimate failure (albeit after more than 30 years in service) of this particular Sika Trocal membrane roof. A detailed survey report ensured any highlighted problems were addressed, with particular emphasis on any areas where standard Trocal details may have been incorrectly fitted.

Although noticeably aged, more than 90% of the area of the Trocal roofing system remained watertight and and in serviceable condition. A handful of problem areas were however identified, and it quickly became evident that further damage had been caused by a number of non single ply roofing specialists who had attempted to repair the Trocal roofing membrane over the years:

Especially over the long periods of time involved, some degree of shrinkage is to be expected as a characteristic of all single ply roofing systems. Today, the more robust systems (generally not rubber) are engineered with mechanical perimeter restraints securely fastening the roof at its edges and eliminating movement through shrinkage. The particular Trocal perimeter detail employed in this case relied upon an adhesive rather than mechanical restraint, which had clearly begun to fail some years ago and was allowing the Trocal single ply membrane field sheet to pull away from the perimeter wall, leading to a large tear along the roof’s edge which was advancing slowly and becoming wider.

To make matters worse numerous inadequate Trocal repair attempts had been made using bitumen based repair tapes and ‘flash band’ etc. Trained Trocal roofing contractors would have been aware that PVC Sika Trocal single ply membranes are not compatible with bitumen, and contact between these substances attacks and degrades the Trocal roofing system causing plasticiser migration / plasticiser loss.

Given the irreversible damage done by the incompatible repair materials, the failed edge detail and the likelihood of this continuing to advance throughout the perimeter of the roof, all were in agreement and the present Sika Trocal Roofing System was deemed to be beyond economical repair.

Falcon Roofline - Sika Trocal Roofing Replacement

The client invited quotes for a number of replacement flat roofing systems, including liquid applied roof coatings and traditional felt roof coverings. As approved installers of all types of waterproofing systems, Falcon proposed that there was no reason to deviate from the type of roofing system and method of attachment that had proved itself over 30 years or so, especially as this would deliver the most cost effective solution both in terms of speedy, reliable installation and allowing the old system to remain in place. In contrast, the application of a liquid roof coating system would have required separate treatment of the failed perimeter detail to prevent severe separation and tenting from continuing to advance throughout the roofing system and provide a stable carrier for the roof coating.

We won the work based on a proposal to overlay the failed Trocal roofing system with the Duranite-MX system, an equivalent polymeric membrane system to the following specification:

  • Thoroughly clear the roof of all all debris vegetation etc;
  • Slice the existing roof covering around its perimeter to release excess tension that had led to the problems;
  • Lay a 500gsm Duratex recycled polyester separation fleece above the Trocal membrane;
  • Install a Duranite-MX polymeric single ply membrane system mechanically fastened through the build-up into the corrugated steel roof deck;
  • Fit mechanical peel-stop bar to roof perimeter and all abutments;
  • Remove perimeter capping and dress membrane to up-stands and beneath capping before reinstating;
  • Install Duranite pre-formed rainwater outlets.


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