What is the function of the BILKA 90° internal angle?

The BILKA 90° internal angle connects two gutter sections at a concave internal corner of the eaves. It is not a roof valley and is not installed under the roofing; it operates within the gutter line itself. It is available for gutter sections of 125 and 150 mm. During measurement, it is checked whether the corner is indeed internal and exactly 90°, because the external angle is a separate product. The water flow and direction towards the funnel are planned from both sides.

How is the size of the BILKA 90° internal angle chosen?

The size must match the adjacent gutter: 125 mm for the 125/90 system or 150 mm for the 150/100 system. It is not chosen based on the diameter of the downpipe. A 125 mm angle is not connected to a 150 mm gutter via a transition because the system profile and connectors differ. Before ordering, the section, coating, and color of both straight sections are checked to avoid mixing incompatible components.

How many color options are there for the BILKA 90° internal angle in LATIVA?

Shopify contains 36 options: 18 each for 125 and 150 mm sections. For each section, there are five matte, twelve glossy, and one labeled as "Zinc" position. 125 mm / Matte / RAL 8017 is SKU LT-1801, and 150 mm / Zinc is LT-1831. Colors and codes should not be taken from the external angle because the two products have separate SKUs. The order must explicitly state "internal 90°."

Where are the supports placed around the BILKA internal angle?

The BILKA installation guide requires one hook on each side of every corner element. For the internal angle, this is especially important because water can be directed from two gutter sections towards the corner. Supports are placed without disturbing the joints and system connectors. The lines are pre-marked with a slope of 3-5 mm/m towards the downpipe. If the angle is a low point, the funnel placement and flow rate are checked separately.

How is the BILKA internal angle connected to the straight gutters?

Connections are made with connecting elements for the same section, with the seal centered and the mechanism closed towards the front side. A 2-3 mm gap is left between the gutter end and the angle for expansion and contraction. Welding is not used, and random silicone filling does not replace the system seal. After cutting, metal particles are removed to prevent rust on the coating. The connection remains accessible for periodic inspection.

How is it checked that the BILKA 90° internal angle will not retain water?

Before final fixing, the continuous slope of the two adjacent gutters, the level of the angle, and the direction towards the funnel are checked. BILKA specifies 3-5 mm/m; a reverse slope around the corner creates a water and debris pocket. After installation, a test water run can be done to observe the joints and drainage. The 90-degree element itself does not correct improperly leveled gutters. For large collection areas, the adequacy of the 125/90 or 150/100 system is also checked.