Concealed gutters: how they work and when to specify one

A fascia or a specially formed section of the eaves screens the gutter. Some systems also conceal the downpipe. Water still needs a fall, an outlet and a route away from the building. The cover changes the appearance; it must not obstruct drainage.

Distinguish a purpose-designed system from boxing in a standard gutter on site. The former provides details for both fixing and maintenance. An improvised screen can hide a leak or prevent cleaning. Retain a practical way of checking the outlet whatever the intended appearance.

Concealed gutters suit buildings with clean lines, particularly where wall and roof read as a single composition. Fewer components remain visible at the eaves. A regular tile-effect steel roof or trapezoidal steel sheet can work well above a restrained façade, provided the fascia proportions fit the building.

An exposed gutter often looks right on a traditional house with wide eaves. Compare both options on the elevation drawing. Matching a conventional system to the trim colour may be discreet enough and makes installation and servicing simpler.

Capacity depends on roof area and shape and on outlet positions. Gutters that look alike from the front may carry quite different flows. Use data for the actual system and check sections that receive concentrated runoff from a valley or a higher roof.

An undersized outlet can overflow in heavy rain. The damage may go unnoticed for longer behind a fascia. Specify what happens if the outlet blocks. Water must not escape into the wall insulation; design the emergency overflow route as part of the eaves detail.

Preserve the continuity of the roof and wall layers around the gutter and downpipe. If the pipe runs close to the insulation, check the thermal performance of that detail. Allow for thermal movement and replacement; a pipe built into masonry without access can be difficult to repair.

Roof sheets, flashings and fascia should shed water in the intended direction. Do not rely on one bead of sealant to keep the entire assembly watertight. Follow the jointing instructions, allow for expansion and pay close attention to corners and stop ends.

Show on the drawings how covers come off or how the gutter is reached. Leaves and sediment collect even out of sight, and guards do not stop everything. An extra inspection may be needed after high winds or autumn leaf fall.

Plan safe access for cleaning. A tall building may require a lifting platform or another maintenance access system; include this cost in the decision. A detail that requires part of the façade to be dismantled for every minor check makes regular upkeep difficult.

The cover should give access to critical joints and outlets. Find out which pieces can be removed without damaging the façade. Ask how a seal would be replaced, a corner cleaned or a blockage cleared while the detail is still on the drawing board.

Also check where water will become visible if something fails. The overflow path must protect adjacent layers. Rather than assuming a blockage will never occur, design the detail so a fault can be spotted and its effects limited without opening large areas of the building.

Compare the complete scope: gutter, downpipe, covers, brackets, flashings, inspection access and any changes to insulation. A retrofit may also require alterations to the eaves. The final cost can therefore differ considerably from the price of the drainage kit alone.

Before ordering, ask for a detail drawing and a description of the water route if the outlet blocks. Identify components that can readily be replaced. A concealed gutter is a sound choice where its appearance matters and the design gives equal attention to drainage and maintenance.

At handover, check drainage and joints before the enclosure is finally closed. Keep photographs and component references. Years later these can identify a part that is no longer recognisable from outside.