Add Second Floor Joist

Framing for floor.

Add second floor joist.

Then set new joists same height as existing ones alongside the old. 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. All the ends of the newly sistered floor joist must rest on bearing walls that are commonly found down the center line of the house and under those walls the beam in the basement must be strong enough to carry a 2nd floor addition or be strengthened enough to carry a 2nd floor. 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.

Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. A day until they re level. Second floor house framing techniques rim joist construction. Tack a beam under the sagging joists.

Most new construction uses 2 by 8 lumber for joists although 2 by 6. Once the rim joist is in place which creates a frame around the perimeter of the second story floor. How much a second floor addition should cost. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.

This size is no longer acceptable when framing a structure. Measure the width and length of the existing joist. Average costs and comments from costhelper s team of professional journalists and community of users. 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.

Purchase the type of lumber that matches the width of the existing joist. The rim joist boards typically 2 by 10s or 2 by 12s install edgewise around the perimeter of. In the past 2x4s or 2x6s were sometimes used as floor joists. Floor joists installed on second or third or higher levels double as ceiling joists for the level below.

Joist span and spacing is set by your local building code. In buildings with basements the first level of floor joists serves the same purpose.