In this video, This Old House general contractor Tom Silva comes to the rescue and saves a neglected, badly decayed garage-door post and jambs.
1. Cut two 2x6s to create a temporarily support post. Lay one board on the garage floor to act as a sill plate.
2. Stand the other 2x6 on top of the sill plate and slip its upper end underneath the header that spans the garage-door opening.
3. Use a hammer to tap the 2x6 to a vertical position, where it'll raise the header and release the downward pressure on the rotted post.
4. Remove all wood trim from the garage-door post using a hammer and pry bar.
5. Use a reciprocating saw to cut through the nails holding the doorjambs to the garage-door post. 6. Pull out the rotted post from between the doorjambs.
7. Dig out all the dirt and rotted wood from the hole where the post once stood. Use a wet/dry vacuum to suck out the last bit of debris.
8. Mix up a batch of concrete and shovel it into the hole.
9. Force a pointed trowel down into the concrete several times to work out all trapped air.
10. Smooth the concrete with a margin trowel.
11. Attach a galvanized carriage bolt to a metal post anchor, then push the head of the anchor down into the wet concrete.
12. Shift the anchor into position, then place the anchor cap over the carriage bolt's hex nut. Allow the concrete to cure.
13. If the doorjambs are rotted, cut away the decayed sections with a circular saw.
14. Cut the new garage-door post from a pressure-treated 4x6.
15. Stand the 4x6 on top of the metal post anchor and tap the upper end of the post beneath the header.
16. Fasten the top of the post to the header with 3-inch screws. Also, screw through the doorjambs and into the post.
17. Use a reciprocating saw to cut a notch into the bottom ends of the two doorjambs that were cut short earlier. Clean up the notches with a hammer and chisel.
18. Drive 2-inch galvanized nails through the holes in the metal post anchor and into the 4x6 post.
19. Cut a pressure-treated 2x4 to extend from the garage floor up to the notch cut in each doorjamb. Cut another 2x4 to fit underneath each jamb.
20. Install the 2x4s beneath each doorjamb, then screw them to the 4x6 post. Remove the temporary 2x6 support post.
21. Trim out the repaired posts and jambs with PVC trim boards. Apply caulk to all joints. Secure the trim with 2-inch galvanized screws.