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Simple design and effective drainage of water from flat roofs

30 of April '21

A leaking flat roof is a big hassle that often involves costly repairs. So how to ensure effective drainage of rainwater from the roof slope? It is worth thinking about this already at the stage of designing the building, so you will be able to avoid failure in the future and protect the facade from moisture. One of the solutions worth considering is Icopal's EPS BMI Drop Panel System. It provides the highest quality, tightness and durability of thermal insulation.

© BMI Icopal

Optimal system solution

Designed by BMI Icopal, the EPS Sloping Plate System is the optimal solution for achieving slopes on flat roof surfaces. Thanks to its shape and the proper placement of ridges and troughs, rainwater moves freely towards internal roof drains, avoiding obstacles present on the roof, such as chimneys and smoke dampers. To create an optimal layout, the architect can use the following elements:

  • base boards, which act as the primary insulation

© BMI Icopal

  • Monopitch panels, which shape the basic slope on the slope

© BMI Icopal

  • Left and right ridge boards, which shape the direction of rainwater runoff

© BMI Icopal

  • Left and right trough plates, shaping the direction of rainwater runoff

© Icopal

  • Counter slabs, precisely directing water runoff and shaping the slope at key locations such as the chimney, skylights and corners

The design received from the manufacturer takes into account not only properly laid counter slope panels, but the entire roof solution system. This includes BMI Icopal products for concrete priming, vapor barrier membranes, self-adhesive underlays, mechanical fixing and top-cover membranes, as well as BMI polystyrene in boards of a wide range of dimensions (up to 3×1 m), boards for laying counter-slopes or adhesive foams for EPS. As a result, the investor receives a roof from a single source, where all components are compatible with each other.

Professional support from the roof design stage

The advantage of the solution proposed by BMI Icopal is professional support from the roof design stage. What does this look like in practice?

Customers send us the designs of their roofs in PDF or DWG format, and our consultants optimize the pitch layout on the roof and propose a suitable solution. We recalculate the design to ensure proper roof drainage at a significant reduction in investment costs. Importantly, elements protruding above the slope, such as chimneys, skylights or hatches, are not a problem - our program proposes a slope layout that will take these obstacles into account," says Grzegorz Gladkiewicz, BMI Icopal Technical Advisory Department Manager.

In the design process, all the needs and suggestions of investors, designers and contractors are taken into account. Changes are consulted on an ongoing basis and the final proposal includes the most effective and economically optimal solution. A clear plan is drawn up for the entire layout of the sloping and counter sloping slabs, as well as a detailed list of all system components. As a result, contractors are able to plan the work so that it goes quickly and efficiently.

The sloping slabs are delivered to the construction site in packages, where each element is accurately and clearly described. The attached list of elements, along with the given dimensions, allows for quick verification of delivery if necessary.

You are cordially invited to watch a video about Icopal's EPS BMI Drop Panel System:

More information at


BMI Group Poland is a leading manufacturer of roofing systems dedicated to sloped and flat roofs. We provide innovative waterproofing and roofing systems to provide protection and peace of mind for homeowners, as well as architects, contractors, roofers. BMI's experts support design processes and provide technical advice in residential construction, public buildings and engineering structures. BMI Group Poland is part of Standard Industries, the world's largest roofing and waterproofing company. In Poland, we combine some of the largest and most trusted brands in the industry: BMI Braas and BMI Icopal.

BMIIcopal offers the highest quality bitumen membranes in Szybki Profil® SBS technology, Szybki Syntan® SBS technology, PVC synthetic membranes, TPO, green roof systems, waterproofing of underground parts and much more.

BMI Braas offers high-quality clay tiles, concrete tiles, panel roof tiles and a wide range of accessories for proper roof finishing.

For more information, visit the company's BMI Icopal page on the A&B portal.

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