How do you detail a roof without an eaves overhang?

At conventional eaves, the roof projects beyond the wall. Bringing its edge back to the wall, or concealing the projection, changes both the outline of the building and the construction of the lower edge. Flashings and drainage still need space, as does the air inlet on a ventilated roof.

This detail suits buildings with a simple outline. On an existing roof, altering the eaves may affect the structure and several adjoining details. Have the designer assess the consequences before shortening any rafters.

The gutter can sit outside the wall or in a recess designed into the façade. A concealed gutter is less conspicuous, and so are its leaks. Provide access for inspection, cleaning and replacement, and decide where overflow or leakage will become visible.

Simply covering a conventional gutter with a fascia will not produce a functioning concealed system. Size the outlets, set the falls and allow the components to move as temperatures change. Detail the downpipe connections and provide a safe overflow route that keeps water out of the wall insulation if an outlet blocks.

For a concealed downpipe, consider how to inspect the joints and where water would go if one leaked. Show access panels on the drawings and specify the order in which covers come off. Water from the enclosure must drain clear of the insulation.

Where space above the wall is tight, gaps in the insulation can occur at the wall plate, ring beam or gutter enclosure. Draw the junction in section, checking both the space each layer occupies and whether it can still be installed after the roof frame goes up.

A PIR board can provide useful thermal resistance in a shallow build-up. Its joints and edges still need careful detailing to limit thermal bridging. If the gutter encroaches on the required insulation thickness, revise the gutter detail to create the necessary space.

Both types of metal roofing can work if they suit the pitch and edge detail. Cut-to-length or modular tile-effect sheets have a wave pattern, while T18 and T35 trapezoidal sheets have distinct ribs. The pattern is prominent at a flush edge. Set out the sheets and flashings before ordering.

Changing to a different sheet profile calls for a fresh look at the detail. Profile height can affect runoff, the appearance of the edge and the space for ventilation. Show the eaves flashing and its fixings in a section drawn to the actual dimensions of the selected sheet.

A ventilated space under the covering needs a clear inlet at the lower edge. Keep the fascia clear of it. Fit bird and insect guards that leave enough open area for airflow. The air outlet must also suit the ventilation layout of the roof.

Arrange access to the gutter before the façade is built. A cover with inaccessible screws can make even leaf removal difficult, especially beside trees. Identify the parts that can be removed without damaging their coating and how to reach them safely at height.

Flush eaves can complement a modern façade, but a wide overhang shelters the wall from rain more effectively. Pay particular attention to the render, flashings and details over windows when designing the façade as a whole.

Compare the frame, gutters, enclosures, seals and maintenance access when pricing the options. A shorter overhang does not guarantee a lower price, as concealing components can add labour. Resolve these details before placing the materials order.