Where is the BILKA 90° external corner used in the gutter system?

The BILKA 90° external corner changes the direction of the gutter around a protruding external corner of the eaves. It is a gutter element with a cross-section of 125 or 150 mm, not an elbow for a downpipe. The same cross-section as the straight gutters on both sides is chosen. If an internal corner is used incorrectly, the geometry and water flow will not match. Before ordering, the actual angle of the building is checked because this product is fixed at 90°.

Which system is the BILKA 125 or 150 mm external corner compatible with?

The 125 mm version is used with gutters and other gutter elements of 125 mm in the 125/90 system. The 150 mm version belongs to the 150/100 system. The angle number indicates the cross-section of the gutter part, not the diameter of the downpipe. BILKA does not allow combinations of 125/100 or 150/90. The coating and color are also chosen to match the adjacent gutters, but the correct size is confirmed first.

What variants and SKUs are available for the BILKA 90° external corner?

There are 36 variants in Shopify: 18 each for 125 and 150 mm cross-sections, divided into matte, glossy, and "Zinc" coatings. For example, 125 mm / Matte / RAL 8017 is SKU LT-1765, and 150 mm / Zinc is LT-1799. The current listing includes five matte and twelve glossy colors for each cross-section. The exact SKU is important because external and internal corners have separate products and different codes despite similar options.

How is the BILKA 90° external corner supported during installation?

BILKA requires one hook on each side of the corner element. This limits sagging and maintains the set slope of the two straight sections. The hooks are not replaced only by the corner connectors. Before installation, lines are marked with a 3-5 mm/m slope toward the chosen downpipes. If the corner is the highest point, slopes can go in different directions; if it is on the water path, levels on both sides are coordinated in advance.

Is there a gap left between the BILKA external corner and the straight gutter?

Yes, the official installation instructions provide for a 2-3 mm gap between gutters and corner elements for thermal movement. The system connector is sealed with a gasket in the middle of the joint. If the elements are pressed tightly without a gap, expansion can stress the joint. If the gap is too large, the gasket may not seat properly. Cuts are made with a cold tool and cleaned of metal shavings before final closing.

Can the BILKA 90° external corner be used on eaves with a different angle?

It should not be forced into geometry other than 90°. The catalog identifies this element as a fixed 90° external corner, so for bay windows, polygonal eaves, or deviations from a right angle, a suitable system or custom-made detail is required. Bending the finished corner on site can damage the coating and sealing. The actual angle is measured before ordering, not determined solely by architectural plans or approximate visual assessment.