Should We Upgrade Floor Joists

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.

Should we upgrade floor joists. Floor joists installed on second or third or higher levels double as ceiling joists for the level below. 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. The notching and boring rules of thumb for solid lumber are shown in fig. 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. You can notch and bore joists without sacrificing critical strength but you must follow the rules. The three main types of floor joists used in home construction are solid lumber i joists and open web floor trusses. If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s.

Positioning the new joist adjacent to the existing preserves precious ceiling but it does come with some potential complications. Joist span and spacing is set by your local building code. This size is no longer acceptable when framing a structure. In the past 2x4s or 2x6s were sometimes used as 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. Follow the rules to keep your floor solid. You should check with your local building department for construction requirements in your area. Tongue and groove edges on many premium floor panels such as weyerhaeuser s edge gold osb panels are designed to self gap.

Sistering installing new larger joists next to the existing ones is one way to bring your attic floor up to code. The floor joist spacing is the distance between the centers of any two installed joists. But larger is not always better when builders are constructing a home or adding a room addition. Spacing joists in your shed 16 inches on center will give you a firmer feel with less bounce and increase the load capacity of the floor.

In buildings with basements the first level of floor joists serves the same purpose. 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. While you may be ok with the joist span at 24 inches the floor will be maxed out to the limits.