Should We Upgrade Floor Joists

You say the span of the joists is probably 6 feet but that the critical measurement.

Should we upgrade floor joists.

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. Joist span and spacing is set by your local building code. See the image below for an example of joists spaced 16 on center 16 o c. If they are older dimensional lumber back when a 2x6 was actually 2 by 6 they ll go even further.

Sistering installing new larger joists next to the existing ones is one way to bring your attic floor up to code. While you may be ok with the joist span at 24 inches the floor will be maxed out to the limits. This size is no longer acceptable when framing a structure. But larger is not always better when builders are constructing a home or adding a room addition.

If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s. In buildings with basements the first level of floor joists serves the same purpose. To avoid buckling subfloor panels should be spaced with a 1 8 inch gap at all edges and ends to provide room for naturally occurring expansion. You can notch and bore joists without sacrificing critical strength but you must follow the rules.

Follow the rules to keep your floor solid. You should check with your local building department for construction requirements in your area. Since the example house we are designing for is 12 feet wide we need to find in the floor joist span table a joist size and centering that can span 12 or wider. The notching and boring rules of thumb for solid lumber are shown in fig.

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. Floor joists installed on second or third or higher levels double as ceiling joists for the level below. In the past 2x4s or 2x6s were sometimes used as floor joists. If they re really only 6 long 2x6 s at 16 on center are fine in fact they ll go a bit further under normal conditions.

Each type of floor joist offers its own unique benefits and drawbacks which is why those working in carpentry all tend to have their own favorite floor joist option though they are still required to be well versed in each type of floor framing. The floor joist spacing is the distance between the centers of any two installed joists. Tongue and groove edges on many premium floor panels such as weyerhaeuser s edge gold osb panels are designed to self gap.