7. Blocking Your Deck Joists

Solid blocking is installed in between joists to stiffen the deck and help prevent the joists from twisting.

Blocking the substructure of a deck.

Do not block outside joist until decking is installed, cut off straight, and secured. Block from bottom side where possible. If building a low deck string line from the outside joist straight before blocking.

When using Shadoe Track on a lower deck you do not want to block until you have laid down all of the decking boards up to where you want the row of blocks.

Drawing of blocking between joists of a deck.

If you place the row of blocking first you will have a hard time fastening the deck boards. So lay the deck boards first, then block, and then keep on decking.

Deck boards installed on the blocked substructure of a deck.

High Decks

Two Ways of Blocking (for appearance)

1) Alternating (but close)

This is similar to regular blocking; however keep the boards closer together.

2) Straight Line

When doing the blocking have one straight line of blocking. This is more difficult, but can look good, and is desireable for an elevated deck where the sub-structure is visible from underneath. The boards need to be toe nailed from one side, and then straight in on the other side.

With Shadoe Track or Joist Cap

Both of these products over hang from the top of the joists and therefore this space must be accounted for while blocking. One way is to just lower the height of the blocking. The other way is to cut a light angle off the end edges of the boards. This is best for high decks so that it is not visible that the boards are lower.

Make sure that the blocking section is lower to allow for joist cap and, or Shadoe Track.

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