Gutter unions are used to join individual lengths of gutter together.A 2mm expansion gap should be left between each length and a fascia bracket should be positioned within 150mm of the union on each side.This union is fitted with a lever type clamp when the gutter in inserted onto the seals (leaving a 2mm gap between each length), the hook is placed over the gutter and is pivoted downwards to clamp the gutter onto the seal. To improve the seal adhesion we always recommend that all seals are sprayed with silicon prior to the gutters being installed.