Split Floor Joists

How to repair a joist with a sister board.

Split floor joists. Work on old houses or even new houses long enough and an encounter with a broken twisted or split floor joist is inevitable. If you have sagging cracked or twisted joists which can happen in older houses this project will provide the extra support the floor needs. 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. Many times more than one.

I suppose somewhere in the world there are floor joists that need to be repaired that have wide open clear joist bays with no pipes wires or obstructions. While it is a good idea to replace rotted material with 2x8s it may require some notching to fit between the sub floor and ledger board. The split is about 1 3 of the way down from the top of the joist starts at the south end of the joist and runs north for about 3 feet. Neither split is all the way through.

The split joist is the first one in from the east wall. Drooping and joist sag can be seen in the photo. No wonder they have split look at the depth of them. I recently had to repair a broken floor joist that had cracked.

The top part of the joist has actually shifted 1 4 to 1 2 to the east. This article provides step by step instructions and pictures on how to make structural repairs by sistering floor joists alongside weak joists. Fixing broken cracked sagging floor joists. Thanks for the suggestion to post a couple of pictures.

Here are shots of a 8 x 8 beam that supports the floor joists. In some parts of its length there is a lengthwise split vertically up through the center. In other parts there s a lengthwise split running horizontally through the center. It is very easy to over cut the notches and remove the waste in two swift cuts.

Anything deeper than this would be a composite joist made up several different ways depending upon the manufacturer. 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. The long view makes the overlap seem longer but i believe the nearest one is less than a foot with very few nails. Use an adequate amount however it does no good to split the wood with too many.

Generally newer home floor joists are made from 2x8s or new engineered i beams older homes however may have 2x6s instead.