Wood – How to fill a hole in wood so that it can be redrilled?

Below quoted advice is pinched from here, How to paint a wood house?

If you encounter any damp, rotten, etc wood during the preparation stage, I highly recommend removing it. When doing so, cut 150mm (6inch) past the last sign of damage ie Get back to good, solid wood. Preferably re-patch with the same wood species.

In your particular situation (outdoors, horizontal surface) I would not recommend filling such a large hole with any kind of filler.

If you feel confident enough in your woodworking skills (or don't mind a challenge and want to learn something new), I say go with the above quoted method. If you were going to paint the wood, not stain it, I would be more likely to go with this method (paint can cover those little mistakes, where as stain is unforgiving).

That said it might just be easier (and cheaper) to remove the 4 pieces of wood completely and replace them with new timber, especially if you are going to stain the wood.

It is highly likely that your beams are made of pressure treated wood. If so, you should try to use the same type of wood in repairing them.

SHIM - When there is a slight gap between a beam and a joist, that can often be cured with shims, slim pieces of wood (preferably of the same type, or if not available, a rot resistant type such as cedar). Shims should be forced in (tapped in with a hammer) so they are tight. Often you can drive shims from opposite sides. Since they are tapered, opposing shims can make a tight level gap filler.

LEVEL - If you cannot shim them adequately and need to move the joists to meet the beams, you need to make sure they remain reasonably level. They may have a slight pitch down away from the house, and that would be ok. You do not want to cause them to shift so that they slope toward the house. In some circumstances, that could lead to a drainage problem.

FILL - The holes in the beams can be filled with slivers of pressure treated wood that are coated with exterior glue. Force several narrow wedges in to pack the holes. Let the glue dry and then saw or chisel the surface flat. You can then drill new holes even close to the old ones.