Do I Need To Cross My Floor Joists

While not the ultimate voice in spans these calculators do provide a reality check.

Do i need to cross my floor joists. Working your way across the floor add the braces between adjacent joists one at a time at eight foot intervals. 2 by 6 or 2 by 8 lumber. Joists that have severe crowns need to be set aside or some of the crown needs to be trimmed off so the floor remains fairly flat once covered with plywood or oriented strand board. For example with such a calculator you will find that for a 15 foot span you need 2x10 douglas fir heart joists spaced every 16 inches.

Walking on joists before all accessories and floor decking are installed i joists are unstable and can roll over if walked on leading to injuries. For more serious weaknesses you may need to shore up the floor joist structure with a cross beam and lally posts. The added depth of these two allows extra support and reduces bouncing. The fixes we ll show work for both solid wood joists and wood i joists.

The only caveat to this is that you need to make sure you have enough space to add another joist. A sister joist is a second joist that goes alongside the first one and stiffens the floor. Don t allow your crew to walk on i joists or install subfloor sheathing until all hangers blocking panels and temporary safety bracing strapping are fully installed. When a load is applied to a joist the wood fibers along the bottom edge go into tension and those along the top go into compression fig.

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. Cross braces may be installed during the construction process or added to older homes and it involves nailing small wooden braces from the top of one floor joist to the bottom of the next joist and vice versa to form an x. Yet it is not uncommon to find bridging not properly installed or missing all together. But there is a catch.

How joists support floors and ceilings joists the horizontal members that span two walls and or beams have to carry the weight of the walls people furniture appliances and other stuff we place on them. For two of the three fixes we show solutions a and b you need access to the floor joists from below. You don t need any special skills or tools to stiffen your floors and all the materials are readily available at home centers. This type of.

Floor joist bridging is critical to the structural strength of a floor as shown in figure 1. 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. If you purchase engineered floor joists that resemble steel i beams these have no crown in them. Joists you may have thought adequate for your attic floor may not come close to being strong enough.