How to Replace Deck Stair Balusters

In this video, This Old House general contractor Tom Silva shares some tricks of the trade for accurately cutting and assembling railing supports.

Steps:

1. Remove the old balusters from between the lower and upper horizontal rails.

2. Use a sliding T-bevel square to determine the angle between the lower rail and the deck post.

3. Transfer the angle to the miter saw by rotating the saw blade to match the angle of the T-bevel square.

4. Rip two ⅜-inch-thick x 1½-inch-wide strips from a pressure-treated 2×4. These nailing strips will be attached to the new balusters.

5. Miter-cut two nailing strips to fit between the first two posts. Set one strip into place atop the lower rail.

6. Determine the on-center dimension of the balusters. In this case, it’s 5 inches.

7. Clamp a 2×2 cedar baluster to the post at the bottom of the staircase.

8. Stretch a tape measure from the baluster to the next post. Raise or lower the tape until the reading at the second post is easily divisible by 5. Here, we held the tape at 50 inches.

9. With a helper holding the 50-inch graduation against the post, use a level to mark the nailing strip every 5 inches.

10. Remove the lower nailing strip and hold it against the upper nailing strip. Transfer the 5-inch baluster locations onto the upper strip.

11. Miter-cut the bottom ends of all the 2×2 cedar balusters to the same angle as the nailing strips.

12. Set both nailing strips on top of the lower rail.

13. Stand the balusters on top of the nailing strips, then draw a line along the underside of the upper rail and onto the balusters.

14. Miter-cut the balusters to length using the miter saw.

15. Prime and paint all surfaces and ends of all the balusters.

16. Use a layout square and utility knife to cut score lines into the nailing strips, indicating where to position the balusters.

17. Prime and paint all surfaces and ends of the nailing strips.

18. Nail each baluster to the upper and lower nailing strips with a cordless brad nailer and 1½-inch brads.

19. Secure each end of the balusters to the strips with two 2-inch-long stainless steel screws.

20. Slide the pre-assembled balusters in between the upper and lower rails.

21. Fasten the balusters in place by driving 1½-inch stainless steel screws through the nailing strips and into the rails.