Replace or sister? Floor joists


Old 03-23-05, 01:57 PM
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Join Date: Jun 2004
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Replace or sister? Floor joists

This 100+ year old house has joists in the front of the house (for first floor, joists are accessible in basement) made of 3x7 inch wood about 20 feet long spanning about 16 feet.

Problem is that at the front of the house three joists have a problem

1) the first joist only goes about halfway across the span and then another one starts. They are not connected to each other and are about 3 inches apart and only seem to be supported by the fact they are nailed into the floor above.

2) next joist had a crack that caused sagging and bouncing. It was jacked up using a house jack.

3) the last joist is cracked about all the way through and is causing bounce and probably sagging.

Since we are trying to sell the house I want to repair the problem. My original plan was to cut the joists and remove them and replace with some 2x10 joists.

All wiring and plumbing is either attached under the joists or along its side (not passed through the joists).

How would I sister the joists? Would that pass an inspection as a proper repair?
Can I use 2x10s?


Last edited by MikeJoel; 03-23-05 at 02:18 PM.
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Old 03-24-05, 01:56 AM
Join Date: Dec 1999
Location: South Dakota
Posts: 3,140

Without seeing them it is only a guess. But first of all yes, you can sister them. 2nd of all, given the dimensions you gave 3x7, a 2x10 might be too wide so fit on the sills. I would probably use a 2x8 put it up along the side of your joists and nail, preferbably useing a stick nailer. However, since you are getting ready to sell it, you shuld probably have one of your permit people or an engineer look at it first and get a professional opinion from someone who can see it. This could be a sticky subject during your sale and closing. It is better to do it right the first time. Good Luck

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