Supporting Floor Joists In Basement

Be suspicious of wood posts set on dirt floors or wood posts with concrete poured around the post bases.

Supporting floor joists in basement. They are made from metal and have an adjustable screw top that can be raised to fit the space between the floor and ceiling of the basement. Insulate basement rim joists. Floor joists are sometimes undersized for the distance they span and the weight they need to support. The joists in most crawl spaces are supported by foundation walls and by a.

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. Years ago while working as a carpenter i helped stiffen a bouncy floor by nailing a new 2 10 to each of the 2 10 joists that supported the floor. For now we ll look into supporting the floor joists with a floor joist beam. As the posts slowly rot and melt into the floor the house settles accordingly bottom to top.

The widest span in the floor joist span table in part 2 of this tutorial module showed that floor joists can span 17 2 if they are 2 x 12s spaced 12 o c. But larger is not always better when builders are constructing a home or adding a room addition. A basement post is usually installed to counteract a sagging frame in a wood frame house. A joist support is the horizontal beam that supports the floor joists.

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. In the workroom below the bedroom and bathroom the double joists which supported load bearing walls above had sagged. It was a complex expensive job. The joist support helps reinforce the floor so it can handle the weight load it needs to.

When the sagging joists are level apply a generous bead of construction adhesive to the existing joist. Working in the unfinished basement below the bouncy floor we had to remove the plumbing and electrical lines running through the joists and then rerun the lines. In some cases additional joist supports will have to be installed before there can be extra heavy objects on the floor. If your house is built over a basement first inspect all of the basement support beams and posts where they meet the floor.

Typically the posts are eight foot adjustable devices that can be placed under a sagging beam or floor joist. Lag screws if you re having trouble nailing. Then attach the sister joist using three 16d common nails driven every 16 in. Over time the joists will sag or become bouncy because they re not beefy enough to support the load imposed by people furniture.

Driving 16d common nails in old hard wood is difficult. Structure is only as good as the support under it.