Wooden windows can swell in wet weather. Try rubbing candle wax along the sticking edge of the window. If that does not work, plane away some wood as shown here Tools and materials Plane, hammer, screwdriver

Sticking opening edge You can plane the opening edge of a casement in situ. Take off enough extra wood to allow for decoration. . Sticking top or bottom edge Unscrew the casement from its hinges so that you can plane the sticking edge.

Repositioning fasteners
Movement of wood due to damp weather can also make fasteners difficult to close, or lead to loose, rattling windows. Fix the problem by adjusting the fitting positions, as if you were fitting from scratch. If adjustment only requires minimal movement, you may have to move the fastener so you can fix into solid wood.

Extracted from DIY- Know How With Show How published by Dorling Kindersley, price £25.00. Copyright © 2006 Dorling Kindersley Ltd, Text copyright © 2006 Julian Cassell and Peter Parham