Two-Stage Roof Outlets

Drainage solutions are an integral part of modern architecture. Unfortunately, we are increasingly encountering problems with flat roofs related to failures of vapour barriers or their insufficient execution.

Problems with Drainage Installation Without a Two-Stage Roof Outlet

The main issue with constructions without a two-stage roof outlet is the complicated connection of the vapour barrier to the piping, i.e. sealing the penetration point through the roof slab. After installation of the vapour barrier, the roof must be temporarily drained; however, once the thermal insulation is installed, the installer can no longer access this point to create a proper connection.

This roof detail is particularly exposed to the effects of water vapour. Firstly, because the opening in the roof slab facilitates vapour penetration into the structure. Secondly, because water flowing into the pipe from the surrounding environment cools it down, increasing condensation on its surface. Even minor defects therefore become much more pronounced at this location. With increasing building airtightness and higher differences in vapour pressure, this effect becomes even more significant.

Solution for Drainage of Insulated Flat Roofs

One of the elements that helps prevent these issues is the two-stage roof outlet by TOPWET. TOPWET roof outlets feature an integrated sleeve, which significantly simplifies the connection to waterproofing layers, and a durable construction made of PA6 polyamide thermoplastic. Long-term reliable performance is further supported by a system locking leaf guard.

In a two-stage configuration, two roof outlets are connected using a seal, ensuring perfect tightness at both the vapour barrier and waterproofing membrane levels. This connection is designed to be easily installed during the step-by-step construction process of the roof.

How the Two-Stage Roof Outlet Works

he two-stage roof outlet is connected with its sleeve to the vapour barrier layer. It features a double-wall construction, which significantly reduces the risk of condensation forming on the pipe.

After the thermal insulation is installed, an extension (TWN) is fitted and passed through the insulation layer down into the seal of the roof outlet. The extension length is adjusted by cutting and then anchored using system washers and roof fasteners. The final step is to connect the sleeve to the waterproofing membrane.

Additional Advantages

One major advantage is that in the case of electrically heated roof outlets, the power supply cable only needs to be routed to the bottom roof outlet, for example along the downpipe, without the need to penetrate the vapour barrier.

Worth mentioning is also the two-stage solution using two single-wall roof outlets (TWJ). This option is particularly suitable for structures where there is insufficient space for a large construction opening or where a refurbishment roof outlet is required to connect to existing piping.

Do Not Hesitate to Contact Us

If you have any questions or need assistance with a specific project, feel free to contact our technical support line at +420 777 701 241 or email us at podpora@topwet.cz.