I need to notch out a ceiling joist in my attic to make way for a ventilation duct coming from a new ventilation fan. I have a rancher. The roof is A frame construction. The joists are 2 x 6. I need to notch out (cut a square completely through) about 4 inches high by 4 inches wide. This would leave about 1.5 inches of the joist left in this 4" gap. Can I do this? If not what are the alternatives. I thought of raising the ventilation fan box but don't now how to extend the box on the bottom. Can I sure up this one joist somehow to make the notch Ok? Any help is appreciated. Thanks.

Jay

 

I would take a 6' piece of 2x6, and hand nail it with 16 pound sinkers, in a Z shape all the down the board. This 6' piece is mnailed to the opposite side of the rafter bottom you are going to cut. This will reinforce the 2x6 run and you will be fine.

 

Thanks for the response Jack. I understand what you're saying. What if the sistered 2x6 must be notched as well to accomodate the duct. Should I take a third 2x6 and do the same? Or is it ok if the sistered 2x6 is notched as well? Thanks for the help.

Jay

 

It would be best not to notch the sister joist. but, do not put a third one on. If you do this you will shift the load bearing capabilty sideways, and your truss may pop. If, it was absolutely necessary to notch the sister run, I would put a strip of plywood between the sister and the rafter run.

 

HELLO
FROM WHAT I CAN UNDER STAND YOU WANT TO NOTCH A CEILING JOIST NOT CUT A TRUSS, IF THIS IS WHAT YOU ARE DOING TAKE
2X6 RUN IT ACROSS SEVERAL OF THE JOIST AT A 90 DEGREE TO THE JOIST ON EACH SIDE OF THE NOTCH USE 3 1/2" SCREWS, SCREWED INTO THE NOTCHED JOIST SO NOT TO POP THE NAIL IN THE SHEET ROCK........