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Nestboxes for the roof

Swifts flying at low level over rooftops

Image: Nigel Blake

If you're in the process of purchasing or building a new house or extension, ask either the developer or builder to fit internal nestboxes for swifts, house sparrows or starlings into the design of the building.

The box, and new entrance hole, should be located at the same place as any existing nests and access should be a slot or hole, usually where the soffit meets the wall. It's worth remembering that places for new starling nests are best located away from windows, doors and bedrooms as they can be a little noisy and messy.

Making an entrance

In 2001, new breather membranes were introduced to replace the old bitumen-based roofing felt. This means that no 25 mm gap needs to be left under the eaves in new roofs, making it necessary to make small holes in the soffit to allow birds access to their nests. The holes should be positioned as close to the wall as possible.

In open soffit construction, birds usually enter the roof by the eaves at the junction of the soffit and fascia. Nests are usually just inside the roof, confined to the closed cavity or solid brickwork ledge.

Ensure that the hole dimensions are suited to the species you would like to attract. The minimum diameter of the entrance should be 32 mm for house sparrows and 45 mm for starlings. Swifts require a 'letterbox' entrance of a minimum of 65 mm x 25-35 mm. Visit Swift Conservation's website using the link on the right for more information about attracting swifts to nest in your roof.

If you have an older property, particularly with a pantile roof, birds may enter the roof under ill-fitting tiles and will nest in the cavity sometimes created between tiles. Where this is not feasible, nestboxes are an alternative.

Internal boxes

As an alternative to angled boxes, an angled piece of plywood in between the joists resting on the ceiling plasterboard prevents birds from getting further into the roof void. The insulation quilt ends at the plywood partition, thus preventing obstruction of the eaves for ventilation while still allowing access for birds. If wire mesh is fitted between the joists and the partition, the birds cannot get any further into the roof space.

It is also possible to provide concrete nest boxes to lay on the brick wall in the boxed eaves. If nest boxes are used, it is advisable to place them away from windows. Visit the Swift Conservation website for more details about these boxes.  

Birds dislike nesting on insulation quilt, particularly the glass fibre types, and show a preference for nesting on un-insulated areas.  

External boxes

If you are unable to retain or create internal nests for house sparrows, starlings or swifts, why not put a nestbox on the outside wall of your house?

Position it under the eaves, away from any windows and out of the direct sun, wind and rain. Click on the Swift Conservation and Swift nestboxes links for more information about external nestboxes for swifts.

House martins build their nests under the eaves of houses. You could place a ready-made nest beneath the eaves, preferably on a north or east-facing wall and not above a door or window. Click on the link to the right, under ‘In more depth’, to see how to make one.

You can fix a small, removable shelf, 25 cm wide, about 2 metres beneath the nest site to catch any droppings. At the end of each season, you can take it down and clean it off, replacing it the following year before the birds return in April and May.

The download documents on this page have been supplied courtesy of Swift Conservation and Swift nestboxes.