Use galvanized nails, as these will not rust. Birdhouses need not be painted, but the box may last longer if you paint the outside. Never paint the inside of a birdhouse. If you paint the outside, use dull (not bright or glossy) colors that blend in with the surroundings. Nest boxes that don't match the vegetation may be easier for predators to find.
Climate Safety: A safe birdhouse is snug and comfortable for nesting birds, without being subject to extreme heat or cold, rainy leaks or damaging winds. To keep a house safe from the weather. Choose a bird house design with ventilation holes in the upper part of the walls to circulate fresh air and prevent the house from getting too hot and suffocating or stifling chicks. If the design does not include ventilation holes, drill unobtrusive holes in the corners or sides of the house. Do not drill holes in the roof, however, where leaks could occur.