When replacing or repairing decking, stubborn screws are a common problem. Common Phillips head screws often strip as they are being installed. Don't worry, there are lots of options to remove screws and this method allows you to remove screws without damaging your decking.
Place bit in drill-driver that corresponds to screw you wish to remove. Make sure that bit is secure and that drill-driver is set to reverse drive.
Insert bit into screw head and hold firmly. If enough pressure is not used, the teeth of the screw head may strip.
Hold down drill-driver trigger until screw is completely extracted from boards.
Try to extract the screw using a normal (most commonly Phillips) bit. Make sure your drill-driver is set for reverse drive.
If this produces no result, insert a drill bit that corresponds to the size of screws you are removing. You can check this by taking the bit and placing it in line with the screw head. The bit should be smaller than the shaft of the screw. Drill a hole in the broken screw.
Attach the proper extractor (sets come with a chart that cross-references screw sizes with stamped extractor size) to your tap wrench and insert it into the hole. Turn counterclockwise.
The extractor acts in the same way as a wine corkscrew might: gripping the sides of the hole you have made. As you turn, the broken pieces of screw should unthread themselves, leaving the original threaded hole undamaged.
If wood needs to be replaced, cut away board around troublesome screws with a reciprocating saw.
Insert a metal-cutting blade into the reciprocating saw and make sure it is secure.
Saw off remaining screw posts so that they are level with the beam they are secured in.
Don't lose the chart that comes with your extractor set: The wrong size drill bit or extractor can ruin your efforts. When it comes time to replace screws, consider using 'square' or 'star' head screws to avoid the problem of stripped screws.