Roof and Terrace Waterproofing

Roof waterproofing comes up in three typical scenarios: building the system correctly from the start on a new building before the finish layers go on; renewing the waterproofing on an existing roof once leaks appear; and addressing waterproofing together with the renewal of the roof covering or thermal insulation. In all three cases the first step is the same: inspecting the existing layers, falls and drainage points on site. The trace of a leak on a ceiling can be metres away from the actual damage in the membrane, which is why no system should be proposed without a survey.

The first question that drives system selection is how the roof is used. On non-accessible roofs — surfaces reached only for maintenance — the waterproofing remains exposed as the final layer, so UV resistance comes first; slate-surfaced bituminous membranes or synthetic membranes are the usual choice. On accessible roofs and terraces, the waterproofing is planned for foot traffic and the load of the finish build-up: it is either covered with a protective screed and paving, or a liquid-applied system that can be walked on directly is used. A system chosen without making this distinction means either unnecessary cost or premature wear.

Whichever system is selected, the critical zones of the application are the same. In our site experience, the great majority of leaks originate at the following points:

Polymer-modified bituminous membrane application is the most widespread and proven method in roof waterproofing. The membranes are torch-welded at the seams and, on critical roofs, laid in two staggered layers, producing a continuous and verifiable water barrier. On non-accessible roofs, a slate-finished top membrane provides UV protection. We work with a range of proven product lines in these systems. The 2,500 m² Proof Membran installations we have completed at industrial facilities are among our reference projects for this system on large industrial roofs.

TPO and PVC synthetic membranes are lightweight single-layer systems whose seams are joined by hot-air welding. They offer advantages on wide-span industrial buildings, light metal roofs and fast-track projects, and can be detailed as mechanically fixed or ballasted. In this group we install a range of proven systems; a 1,200 m² Ravaproof application was also completed under this scope.

Liquid-applied waterproofing builds a seamless membrane from polyurethane, hybrid or cementitious elastic materials applied in coats by brush, roller or airless spray. Its strongest points are the absence of seams and easy adaptation to complex geometry, which is why it stands out on detail-heavy terraces and in refurbishment work. In this group we work with leading international systems. The final system choice is settled against the following criteria:

Because terraces are effectively accessible roofs, their waterproofing has to be planned together with the falls, drainage and finish layers as a whole. A classic terrace build-up consists of a screed to falls, the waterproofing layer, a protection layer and the finish. Minimum falls must carry water to the drain without interruption, the waterproofing must be turned up the parapets to a sufficient height, and the paving joints must be resolved so that they do not take in water. Terrace waterproofing lasts when this entire chain is built correctly.

On existing terraces in use, the question we hear most often is whether the tiles have to come up. Waterproofing over existing tiles can be done without removal, using polyurethane or hybrid liquid-applied systems, provided the substrate is sound and suitable for adhesion. Before application, the floor is checked for hollow and debonded areas, the joints and drain details are prepared, and the coats are applied over a system-compatible primer. With a UV-resistant top coat the surface can be walked on directly, and a new finish can be laid over it if preferred. Because this approach eliminates demolition, debris removal and re-tiling from the bill, it is a serious advantage in refurbishment work.

A terrace renovation is also the right opportunity to treat roof insulation as a whole. In the inverted roof detail, where thermal insulation is resolved together with the waterproofing, compression-resistant XPS boards are placed over the waterproofing layer; the membrane is protected from temperature swings and mechanical impact while the building's energy loss is reduced. We use leading thermal insulation products in the thermal insulation layers, combining the two insulation disciplines in a single project under a single responsibility.

EREL Yalıtım's way of working comes from its engineering roots: with our engineering team's approach, every project is assessed with material chemistry and substrate compatibility in mind. Which primer a bituminous membrane needs on which substrate, how a polyurethane coating will adhere to existing tiles, how a synthetic membrane's mechanical fixing should be detailed — these decisions are made on technical data, not guesswork. System details are finalised before work starts and the job is run to a technical specification.

Our references are the field record of this approach. We have completed thousands of square metres of Proof Membran and Ravaproof across industrial and residential projects; the application we carried out with a crystalline waterproofing system at a major airport's water reservoir demonstrates the company's technical competence on critical structures. The same discipline applies at every scale, from a residential roof to an industrial facility, which is also what makes us a dependable applicator for B2B contractors.

The process runs turnkey: survey, system proposal, removal and surface preparation, application, testing and handover are gathered under one responsibility. Our clients — including international property owners who manage their Istanbul buildings from abroad — carry no burden of coordinating separate crews; at every stage of the work, their single point of contact is EREL Yalıtım.