Add Strength To Floor Joists

The notching and boring rules of thumb for solid lumber are shown in fig.

Add strength to floor joists.

Sistering is the process of adding a new joist next to each existing joist. Framing lumber is the typical. Doubling the thickness of joists by adding material to their sides increases strength and stiffness. Common sense tells you that large floor joists can carry more load and spacing joists closer together also increases the load bearing capacity of a floor.

The extra two inches of vertical distance when a floor is framed with 2 x 10 joists rather than 2 x 12s can be quite important for example. Remembering his boyhood kitchen tom makes sure that any new floor he builds is rock solid. But larger is not always better when builders are constructing a home or adding a room addition. Follow the rules to keep your floor solid.

Doing so strengthens weak joists and can help straighten sagging joists. In the case of 2x6 joists you can pair them up with additional 2x6 joists by nailing them together side by side. Nail the block in place with 16d nails on each side of the blocking. Floor joist bridging is critical to the structural strength of a floor as shown in figure 1.

Repeat this process every 24 to 36 inches down the. When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started. While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length. Place the lumber block between the two joists.

Photo by richard howard 4 ways to stop the bounce. How to sister a floor joist. Proper bridging distributes the load on the floor to other joists and over time prevents floors from sagging and squeaking do to floor joists twisting and warping. If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s.

Details to minimize the chance of future squeaks and to help secure the new floor sheath ing start by spreading a generous amount of construction adhesive over the old planks. Sistering joists means beefing them up with additional material. Lay the new sheets perpendicular to the floor joists and orient panel ends over joists. Cut a piece of 2 by 6 or 2 by 8 lumber according to the width.

If the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists. Bottom of the floor joists instead of or in addition to being installed on top. Measure the width between the span of two joists. Joist span and spacing is set by your local building code.