Cut Roof Joist

I have installed a new HV/AC unit on my roof, It's bigger than the old one and a little heaver.
But what my question is after getting it installed I started getting cracks in the ceiling of my master bedroom, Big Cracks...After many days of trying to figure out what the problem is I finally found it.
The people that we bought this house from back in 1991 installed a whole house fan in the hall and what they did to install it was cut one of the ceiling joist out, Three feet of it, And that joist ran right under my new HV/AC unit so it weekend the whole roof. My question is how do I repair it where they took out that three feet.

The good joists on each side of the hole should be doubled up, as long as possible, best if you can get both ends on bearing walls, as each will be carring 50% more weight than they were designed for and nail or screw the crap out of it as you want it make it as one..
You may have to shorten the cut out ends by 3 inches and then slip a single hanger on the end of each.
You are going to put a double joist across the end and hang them from your double on each side, Install the double hangers first drop in the new doubles and finish nailing the hanger, and you are up to code.

You may have to jack up, or brace up the existing joists while doing this, to avoid a permanent sag at that spot.

slownsteady said:

You may have to jack up, or brace up the existing joists while doing this, to avoid a permanent sag at that spot.

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I am going to remove the whole house fan all together I never liked it anyway to noisy .
So would I still do the same fix,? Or would I do the work on the one joist that is cut.?
And yes I do know how to jack up the ceiling to get it level, Just not sure what the code in this area requires for this type of fix.
I want to think you for any help you can give.

If you can get a full length in there you could just double up the cut one, if not as long as you can, I would be going for at least 3 to 4 ft over lap one each side with lots of nails and screws.
In these kinds of repairs engineers call for 2 nails every 3-6 inches in a 2x4, 3 nails in 2x6, 4 nails 2x8, 5 nails in 2x10. Less nails of you can get to 2 bearing walls.
Engineers are also looking at loads and things so anything you get here is just a guess.

I would glue and screw. Unless you have a power nailer that's a lot of hammering and for me anyway hand nailing loosens other things up. When talking screws there are many types and you don't want to use the drywall type that are real long. You want the type for construction or deck work. I like a brand called guard dog because of their drive end. Regular Philips are tough to drive sometimes without spinning the bit. I would use a yellow wood glue and pattern of screws suggested above. A big C clamp works great to pull them together to get started.


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nealtw said:

If you can get a full length in there you could just double up the cut one, if not as long as you can, I would be going for at least 3 to 4 ft over lap one each side with lots of nails and screws.
In these kinds of repairs engineers call for 2 nails every 3-6 inches in a 2x4, 3 nails in 2x6, 4 nails 2x8, 5 nails in 2x10. Less nails of you can get to 2 bearing walls.
Engineers are also looking at loads and things so anything you get here is just a guess.

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That all sounds good, I will get the longest 2 x 4 s that I can get up there glue and screw them every 4 inches, That should pass code and make the inspector happy.
Thanks.

bud16415 said:

I would glue and screw. Unless you have a power nailer that's a lot of hammering and for me anyway hand nailing loosens other things up. When talking screws there are many types and you don't want to use the drywall type that are real long. You want the type for construction or deck work. I like a brand called guard dog because of their drive end. Regular Philips are tough to drive sometimes without spinning the bit. I would use a yellow wood glue and pattern of screws suggested above. A big C clamp works great to pull them together to get started.


Sent from my iPhone using Home Repair

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I want to think you guys for all of the help, Now I know what needs to be done, I wont be able to get to now, I pulled a mussel in my leg and the doctor said to stay off of it for two weeks, Just my luck. I will try to post pictures of the job when I am done.

Ya I forget that not everyone has a nail gun..