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Ken
MVM
join:2003-06-16
Markle, IN

1 recommendation

Ken to garys_2k

MVM

to garys_2k

Re: Structural Question, Floor Joist Holes

Dimensional lumber as I can tell you are aware has the top and bottom of the joist under the most stress. So ideally you want to drill in the center whenever possible. However the midpoint of the span is under the most stress and the close to the ends like in your picture the top and bottom are under much less stress. So drilling holes like that near the bottom and near the end of the joist is not nearly as bad as drilling in the same location in the middle of the span. This is only true for dimensional lumber though. Check if any of the joists are cracked, and check if the floor has sagged more than a normal amount. If nothing has happened yet it never will unless you greatly increase the load on the floor above.

cdru
Go Colts
MVM
join:2003-05-14
Fort Wayne, IN

cdru

MVM

said by Ken:

the close to the ends like in your picture the top and bottom are under much less stress. So drilling holes like that near the bottom and near the end of the joist is not nearly as bad as drilling in the same location in the middle of the span. This is only true for dimensional lumber though. Check if any of the joists are cracked

In the 2nd picture, looking at the wood grain, if it was going to split due to tensile stress it would have happened right there.

Ideally you drill in the center. The fact that the house is 50 years old probably is a good sign. I wouldn't worry about it unless there is obvious splitting damage that isn't seen.