Our swift Nest Boxes are made to RSPB specifications. Rather than using plywood which will need tobe painted periodically we use rough saw larch which will last many years longer and with virtually no maintenance. Inside the box a depression or cup has been created on the floor for the swifts to lay their eggs in. The first year is spent gathering bit of spider webb and feathers they find on the wing to line the nest cup, and then they start to lay eggs the following year. For this reason we do not suggest you clean the box out.
The nest box should be put up under the eves of the house at least 5 meters up.
It doesn't matter which aspect the box is put on as long as it is not in full sun all day, to avoid the risk of the chick's over heating.
Other birds using the box. House Sparrows and sometimes Starlings can take up residence in the box which then prevents the swifts nesting. If this is likely tobe a problem and you can easily access the swift box temporarily cover the entrance. Sparrows and Starlings start nesting early in spring, while swifts start to arrive April May so if you uncover the entrance in April the chances are the Sparrows and Starlings will already be nesting leaving the swift box for the newly arriving swifts.