Doors made from badly seasoned timber are particularly prone to warping, though once you have corrected the warp it is unlikely to return. However, in some instances the warping is caused by outside factors - such as a radiator sited too close to the door, or bad ventilation. If you suspect that this is the case, take steps to deal with the external problems or the warp may recur.

If the warp is not too severe, there are several ways of forcing the door against the twist. Some of these, however, require the door to be kept shut and in many cases this is not convenient.

If you can keep the door shut, wedging it shut against the warp for a few days may well prove to be effective.

1. To do this, look along the door to check the extent of the warp. Then, with the door just touching the doorstop, measure the gap between the door and stop at the widest point and cut a wooden block slightly larger than this gap.

2. Fit the block at the point where the door and stop shut, so that it touches the stop at top and bottom. If leaving the door shut isn't possible, you can either try altering the position of the hinge on the door frame to take up the twist (see diagram), or else alter the doorstop. How you do this depends on whether you have a stop which is a separate piece of wood nailed on (planted) or one cut out of the wood of the door frame itself (rebated). If you have a planted stop, close the door and cut a block of wood slightly larger than the widest gap.

3. Run the block down the edge of the door marking the stop with a pencil.

4. Prise the stop off. Loosen with an old chisel then pull away from the frame with your hands.

5. Plane the stop then refit it flush with the door. A rebated stop forms part of the door frame and can't be removed. Instead you have to add a shaped piece to the stop to fill the gap.

To do this, measure the length of the gap between the door and stop. Then measure the width at the widest point.

Cut a wedge to these dimensions (see diagram) and nail it to the stop at the appropriate point. Once the wedge is in position, trim it again until you get a perfect fit.

The remedies above only work if the door has warped at the top or bottom corner. If it has warped in the centre you will have to cut a curved wedge tapered at both ends.

Another way to deal with this problem, if you can remove the door, is to try laying it flat, supported on two chairs, bowed side up.

Place some heavy weights on top and leave it for a few days.